Lister Engine Forum
General Category => General Discussion => Topic started by: mobile_bob on December 16, 2006, 02:02:32 AM
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this post is for the purest in the group, those that want more info on concrete mounting of the engine
http://www.slideruleera.net/FoundationsForCompressors.pdf
http://www.slideruleera.net/MachineryFoundations.pdf
the first link is particularly interesting when considering concrete as the mount of choice for a compressor or an engine
seems somewhat opposed to that of the lister recommendation, which is not to say lister had it wrong, but
it would appear there is a case to be made for a shallower, but larger in length and width concrete block.
which opens the possibilty of a shallow, relatively large base that would work well with a genset i would think.
coupled with the matting that they refer to, might be the best of both worlds, low vibration, rigidity, safety, and low sound/vibration transmission
isn't that what most folks want?
not trying to stir the hornets nest, but passing along info for those that are so inclined to read it.
bob g
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I got the same ideas from the information you posted Bob....
I now have a Ukranian mechanical engineer, an Italian black smith and several millwrights at work discussing the best way to mount a stationary engineer on a block.
The engineer is clever...
The millwrights are practical...
The black smith has done this work in the old country...
I think its a case of ballance for best performance first and mount on the biggest practical block. A practical block seems to be open to debate...
Doug
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Doug:
what i have been wondering in consideration of the concrete block and issues with isolation from the house slab and the underlieing soil is
what if one was to poor the floor, leave an opening for the engine base, form up the sides of the opening in the floor at an angle of perhaps 60 degrees
then line the sides of the opening with some high density rubber and then poor the engine base within the rubber lined opening
one would then have an isolated concrete base that would only tighten if the soil compressed or shrank away, also the engine concrete base would be tightly contained
and not be subject to soil shrinkage from the sides which allows fore and aft movement, rocking would also be abated.
i am sure there are other considerations such as the engine concrete base would exert large forces on the floor, so additional rebar would have to be incorporated to keep from stressing the floor and cracking,,
but it should be possible to do
i think you then would have a very well contained, isolated, rigid and solid mounting system.
just thinking
bob g
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Bob,
I tossed that one around before I went the way I did. Unfortunately, the proper material for under your floor (something that drains well like crushed stone) would be all wrong as far as vertical stability goes. You can compact it but it's not going to stay put at 60 degrees. I suppose you could pour the walls or maybe find a precast cistern of appropriate dimension and set that in place before you pour the floor.
Bill
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i c no reason that it would not work, provided the mount block is of sufficient weight to start with.
for instance if you had a mount block of perhaps 6 inches thick and large enough in length and width to encompass and mount not only the engine
but the genhead and related equipment, the end result would be a slab of perhaps a ton
just an idea, one of many :)
bob g
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I know what you thinking Bob I thought about it too.
I have two choices, the block on the rock or the block in the soft wet clay.
The rock will require some bolting. The clay will require a deep pilon because of frost ( six feet deep )
I though about an inverted 60 for a wider foot print and better energy transfer.
No matter what this can't go in my basement so I'm in a different boat than you.
Idealy what we need is a better roid, seriously...
Or a crank driven counter weight spinining anti clock wise to the crank to dampen vibration and a harmonic ballancer to burn of some twist in the crank.
Way off topic, and out of reach....
Flubber, thats what we need Flubber isolation mounts for the block....
I'm grasping
Doug
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Doug:
(this is my 4th typing of this post,, hopefully it will post this time)
it occurs to me that perhaps we are looking at mounting from the wrong perspective.
the question then becomes from what perspective should we be viewing the problem (assuming it is a problem)
we need to limit movement of the engine? yes. but...
do we need to limit the whole engine? no,,,
or a particular part? yes, that part being the crankshaft
we have three planes to work in and 6 ranges of motion, plus the rocking component
the rocking component is the hardest to address if we think inside the box, and use the commonly accepted mounting method where the
crankshaft centerline (c/l) is well above that of the mount. further the rocking component is worst at critical speeds (that rpm during spin up and spin down that the engine lurches around very pronounced)
so going back to the crankshaft c/l viewpoint, how do we reconcile the rocking motion or make this motion a non factor?
by building a steel frame mount that is U or cradle shaped, where the engine is bolted rigidly to the bottom of the U/cradle and
the rubber mounts are attached at the top of the U/cradle legs, inline with the crank c/l plane, and where the crank c/l is in the
middle of these mounts. this way the rocking motion becomes no factor as it rotates around the crankshaft c/l by design.
we are then left with the three planes of movement and 6 ranges of motion
the vertical plane (up/down) can be addressed effectively by varying the thru bolt torque of the donut rubber mounts, effectively limiting the
up/down motion to within the design parameters by tuning in under operation.
this now leaves the other two planes and 4 ranges of motion, this is where the steel cored donut mounts really shine in that they have sufficient surface area
and contact area with the steel components to limit these two planes and related motions by design.
another part of the donut style mount is the top washers that are used to limit torque action or in this case limit travel during the aforementioned critical speeds of the
engine.
this will work!
i am now convinced that i can design a steel frame mounting system that is resiliently suspended, that does the following
1. makes the rocking component a non factor (+/- .005 or less)
2. limits the vertical motion component, to within whatever parameter i want (+/-.005-.010")
3. limits the fore and aft component, to well within (+/-.005-.010")
4. limits the side to side component to well within (+/-.005-.010")
5. provides for critical speed snubbing,
6. provides isolation from the concrete floor and the related structures.
ok,, GuyF. i know you are out there,,, poke this one full of holes! :)
this mount would be superior even to a concrete block that has some movement in a clay bed, where rocking motion is evident.
bob g
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Sounds like you found a technical paper I also read regaurding the U frame idea and moving the " Foundation " support closer to the crank....
I wish I could sleep....
Your probably on the right path from an isolation perspective but I can't get the idea out of my head that guy planted about reducing crank shaft stress and another article I read about vibration induced by mounts and bearing failure.
I don't know.
I got a fly wheel with pits in it on my mind right now Bob.
Vibration aside I just might scrap the engine and call it a day....
Doug
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Doug:
i can relate to the sleep thing,, i finished my last post, went to bed, fell asleep and then woke up thinking about this damn mount thing.
i am a sick, sick man.... :)
as far as your flywheel on the petter, i wouldnt scrap it,, it is pretty much a solid unit, and likely won't fail catastrophically
yours is far less a worry than the listeroid one we saw today.
i say ,, paint her yellow and let her rip!
as for finding the tech paper, no i havent,,, i have just been thinking about this issue for months now.
and i caught a bit of the show "criminal minds" tonight,,, and the brainiac, stated "perhaps we are looking at the problem from the wrong perspective"
that caught in my head, and i went back to the drawing board and rethought the whole system and what we are trying to control movement on, that being the
crankshaft.
the logical progression was in how to limit motion of the crankshaft in the 3 planes , as viewed from the center of the crankshaft.
the rest fell into place once i got my head around thinking from within the crankshaft c/l
bob g
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Is there an echo in here?
http://listerengine.com/smf/index.php?topic=1097.msg14311#msg14311
:D
I know everyone tells me that movement of the engine / generator is a bad thing, but I still think that it's of little importance.
I've mentioned the reasoning why before - regarding the orbit and forces of the crankshaft around the centre of mass in an unbalanced system - so I've pretty much said my piece.
All I'll say now is if you let your engine move a little in relation to the rest of the world it becomes a lot easier to reduce the transmitted thump. The more you let it move on it's mounts, the less force is transmitted to the outside world. Whether that's an important criteria for you is up to you alone I guess.
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GI:
i remember your post now, but the difference is in the purpose of the U design
at 8.5 inches (from your post) you provide clearance for spring and shock mounts, and lower the center of gravity which is fine,
but what i am talking about is moving to approx 12.5 inches, not because of lowering the center or gravity
or to provide clearance but to get the rocking element to be at the crankshaft centerline.
and you are correct in your assessment, in that the more you isolate the more movement you will have and visa versa
you run into that with automobile's, and shock absorber, spring selection and location.
bob g
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In an "echo" from the post GI linked to (mostly to determine if I am upt to speed myself)
The engine without the counterbalance built in to the flywheels will tend to hop up and down and fore and aft due to the movement of its piston/connecting rod and crankshaft masses. The counter weighting cast into the flywheels should (theoretically) be able to counter most of the up and down movement..but cannot counter the induced ratation since they would have to counter rotate to do so. And due to the questionable quality control inherant in the loose association of foundry/machining/assembly companies that "make" these engines in most cases the counterbalancing will only be approximate at best. Since a flywheel that is even a degree of in its relation to the crankshaft will never functionas intended the only way to assure that the counterbalance function is opertainting as the engines designers intended is probalby to get blank flywheels and machine them to a more exacting standard. If someone with the equipment needed to do this began selling them I do not think I would be alone in beating a path to their door with cash in hand. (Please...someone say "foolish Dana...someone already DOES!" and provide a link)
Lets assume that is not an option though and we have to make do with flywheels which are only "in the ballpark" as far as counterbalancing ability goes. At least on a single cylinder listeroid (twins will be trickier) if the flywheels are "matched" to each other as closely as possible so the counterbalances are of equal weight and that weight is indexed to the crankshaft as close to identical as possible.
Is it not mainly the variations in the counterbalance forces of the flywheels that induce rocking and side to side motions? A well balanced engine should be much simpler to "tame" than one with imbalance "issues".
Does it not make the most sense to reduce as much as possible these unwanted forces/motions as part of the basic procideure leading to initial run up of the engine?
I realize that I may be stating the obvious and there may be a post on how to balance and (possibly even) index flywheels somewhere in the archives. I have seen this subject mentioned several times..but have found no such post. However I am new here.
If there is such a post would someone mind directing me to it? I have a knack for missing the obvious. ???
Moving on...let's assume that the counterbalancing of teh flywheels has been made as effective as possible.
In which case the "kindest thing" I think we can do to th engines bearings are to allow the remaining movement to go on unempeded. This should minimize the forces applied to them. But these are very robust..and probably capable of withstanding more abuse than making the engine completely immovable exerts on them. i do nto think they need any knindesses beyond receiving adequate lubrication. And they are easily and inespensivly replaced. This is of course only a "funugis" opinion and nothing more. ;D As is the following:
Doesn't the least amount of wear on the engiens bore, rings, and generator head bearings occurr when they are held rigidly in the same "space"? Doesn't this wear increase progressivly with the amount of movement from a fixed point in space they experience?
What about the exhaust pipe (if more than a peppercan is used) connection?
I believe that a little movement is unavoidable. But I also believe that the immovable object method of mounting listers is due to the fact that when one is looking at a 10-20 year (or longer) working life the cumulative effect of little motions on engiene and aux. parts may be significant. For those who do not expect to run 24/7 or even 2200/365 this may not be significant enough to worry about. But for those who do (and I am one of them) I am afraid that the secondary effect of not using a "immovable object" mount may be unacceptable. Which..considering the position it puts me in is also unacceptable. I want the best of both worlds. ::)
But I only see one way to achieve that.....a counter rotating mass counter balance.
Which unfortunately seems too complicated a project to even begin a discussion on at this point.
Yeah..a little movement may have to be accepted if a concrete block is not employed.
Effective movement snubbers may be the only simple solution.
Are you guys aware of phase change gels? They have the property of going solid when force is applied and back to gel once it is removed. The change can be very rapid and might be applicable here. My hunch is that they would avoid the "spring back" problem with any elasomeric doughnut or spring incorporated in an engine.
I'll shut up now. I have probably strayed far off topic by now.
Probably would have been better off not opening my mouth.
(Huge sigh from the group amid whispers of "I thought he would never shut up...dumbass!")
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i remember your post now, but the difference is in the purpose of the U design
I know, I was just stirring ya ;) - I did mention 8.5" - that's the height of the bare mount - but I was aiming for the machine to be suspended at about the CG height whatever that ended up being.
I thought that in a resilient system, the rocking moment would be around the CG regardless (whereever that may be) as opposed to crankshaft centreline? The forces emanate from the crankshaft, but when they are applied to the machine, they'll simply attempt to pivot the engine about the CG, correct? So following from that, if you can line your CG up with your crankshaft, there's very little arm for the forces to work on and rocking should be minimised.
Or maybe not. It's 8am and I've just come home from another long night shift.
I'll shut up now. I have probably strayed far off topic by now.
Probably would have been better off not opening my mouth.
(Huge sigh from the group amid whispers of "I thought he would never shut up...dumbass!")
Don't stop now, if we all kept our mouths shut, a lot of interesting stuff would have been missed.
Flywheel balance was a hot topic, until we went all crazy with the resilient/concrete mount holy war. There's quite a few threads - I think the "balancing out the bounce" one had some good detail in it. There's been posts of two flywheels on the same engine being more than just a few pounds different.... just another issue to contend with.
Don't really know about wear on the bores/etc. It might be low enough to be negligible, considering that plenty of 'mobile' engines get rattled about in all sorts of orientations on considerably more flexy mounts. One of the more interesting designs I was considering was to simply only suspend one end of a modestly long frame near the engine, and hinge the other end near the genset. The hinge prevents a lot of movement in all axes (if designed right), allows the gen head movement to drop proportionally due to the length of the frame, yet most of the engine jiggle is still isolated by the suspension at the other end. Things such as exhaust, fuel hoses, wiring,etc could be brought out at the hinge end, greatly reducing their movement/flexing. In fact, the more I think about this design, the more I'm inclined to try it out.....
An internal counter-rotating balance shaft would be a little beyond my engineering skills. But a timing belt from the inside of the flywheel to a counter-shaft close by on the frame/crankcase is doable... and it would be relatively easy to time by the seat of your pants. (A tooth back and forth till you found something with the minimum movement, increase counterweight until least movement seen) ;) But of course, that's still more whirling , threshing parts to fail on you. All this work doesn't dampen the movement from the torque impulses though.
The advantage of having a resilient mount is that you can see your improvements in balance directly. It's a little hard to tell if your moving your 2 ton block 0.0003" or 0.00025" when you're tweaking it. And I'll restate my concerns about someone uncrating a new engine, bolting it to the standard block (or more, as more mass is better, right?), and never knowing that he's got a hideously unbalanced machine until some rotating part rips off at speed.
(damn fsocket errors! for those of you that don't know - when you've finished typing your message and your cursor is still in the edit box, type ctrl-a then ctrl-c. Then if it fails and eats your post, you can just repost again, put your cursor in the blank message box and press ctrl-v to get your message back to where you had it.)
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GI:
we are not concerned with center of gravity, as it is likely well above the crank centerline.
for example
if we find the center of gravity and suspend the engine at that point we then have the crank centerline below this point,
thus when the rocking component is factored in the crankshaft will move in an arc.
now if we set the mounts inline with the crank centerline, the engine can be free to move as far as it likes in the rocking motion
with no effect or movement on the crankshaft or flywheels as now they are in the pivot point of the arc.
automotive engines are designed this way, the front and rear mounts are located so if you draw a line between the centerlines it will intersect in the center of the
crankshaft. the engineering books have numerous reference to this.
the lister is easier in this regard as the crankshaft is level unlike the downward slant of an automotive crankshaft.
the parts that we want to control stresses from movement are the crankshaft, flywheels, and main brgs (because they deal with supporting these parts), all other parts
while rotating around this pivot point due to rocking don't have detrimental stresses applied to them, (provided of course we are talking a small amount of movement and not a 1/4 turn!)
as far as the rocking moment, we can't do much about that, the engine will always have a rocking moment no matter how we mount it, but we can design to place the center of this moment where we want it,,, and the centerline of the crankshaft is much preferred to the center of gravity or center of mass.
i need to get a scanner and figure how to post pics, so i can put up some reference diagrams and pictures.
i know sometimes my expanation leaves much to be desired, and a picture is worth a million key strokes :)
Dana:
don't ever feel like you need to shut up!
it is thru the open exchange of idea's and thought that much is learned.
sometimes the simplest of question's starts a debate which brings forth all sorts of interesting and pertinent information.
besides some of our debates on this forum are down right entertaining, and yes sometimes even "knock down drag outs"
with name calling, sand kicking, screaming and yelling,,,, just like a family :)
wouldnt be much fun if we didnt ruffle some feathers once in a while.
bob g
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if we find the center of gravity and suspend the engine at that point we then have the crank centerline below this point,
thus when the rocking component is factored in the crankshaft will move in an arc.
now if we set the mounts inline with the crank centerline, the engine can be free to move as far as it likes in the rocking motion
with no effect or movement on the crankshaft or flywheels as now they are in the pivot point of the arc.
Aha! Gotcha. Didn't seem quite so obvious this morning... but it's a little bit more obvious now after a bit of sleep. :D
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sleep? who needs sleep?
just ask Doug :)
yur burnin daylight pilgrim, er moonlight???
bob g
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Burning the Lime light Bob lol....
How do you figure out all this centering the forces at the crank stuff Bob?
I know it relates to the mass of the block shifting rocking elements to the crank center but how did you arive at the math to do it?
I spent the night pondering grout, blocks and machine plates....
Have a safe and happy holiday.
Doug
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Doug:
it is not a mathematical problem but rather a geometric problem
when you consider the enormous gyro forces placed on the crankshaft and its support brgs (mains), and the flywheels, it is fairly easy
to see that we don't want the crank to move at all if possible. (If i remember correctly this is the prime concern of GuyF, in that he has concern
over movement of the crankshaft inducing stresses that might lead to failure)
so if we want to stabilize the crankshaft we have to center the rocking component at the centerline of the crankshaft, then the rocking can
rock and roll all it wants to without effect on the crankshaft, brgs or the flywheels.
if we bolt the engine down to a base that is below the crank centerline, the crankshaft will move thru and arc that has its pivot point roughly at the
center of the bottom of the case, or in a 6/1 an arc of approx 12.5 inches (at least), and perhaps alot more depending on the spacing of the subframe mounts, or the
length of the concrete block it is all mounted to (should the block be sitting on unstable earth such as damp/dry clay)
i wish i could figure how to post a diagram, i think i could explain it more clearly with a couple of pictures.
i guess i will have to learn a new skill,
maybe i can just draw a picture and take a digital pic of that and email it to someone that can post the damn thing...
what happened to blackboards anyway?
bob g
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Please draw me a picture I think I follow, but I'd like to see it on paper.
Doug
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the issue is harmonics. a destructive harmonic can develop in any rotating device. that frequency could be the frequency of the bolted down engine onto concrete (however, experience of thousands of these engines tells us that is not true), or a soft mount (since every mounting situation is different, an unlucky sod could accidently find this frequency). the safest route is the bolted down engine on concrete. Having said that, soft mounts could work as well or better.
captain steven
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when you consider the enormous gyro forces placed on the crankshaft and its support brgs (mains), and the flywheels, it is fairly easy
to see that we don't want the crank to move at all if possible. (If i remember correctly this is the prime concern of GuyF, in that he has concern over movement of the crankshaft inducing stresses that might lead to failure). So if we want to stabilize the crankshaft we have to center the rocking component at the centerline of the crankshaft, then the rocking can rock and roll all it wants to without effect on the crankshaft, brgs or the flywheels.
This is the bit I've always had trouble with.
For reference, I'll define my axes. Looking at listeroid side on, directly facing the flywheels with a generator off to the right, x is left and right, y is up and down, z is in and out of the image. From there, you can define planes - the x-y plane is the one looking side on at the flywheels, the x-z plane is the view from the top, the y-z plane is the view from the side. All of those can be taken as 'slices' along the missing axis, eg the x-y plane is an infinite number of slices in the z-plane. If you want to sketch out a listeroid on a bit of paper and label the axes, it'd probably help with what's to come.
So, we're all looking at the same thing? Good.
If :
- The forces are generated from the crankshaft/reciprocating mass due to imbalance between reciprocating/rotating masses and power pulses.
- The bulk of these forces are in a plane at 90 degrees from the crankshaft, that is a plane defined by the x and y-axis.
- The forces that are parallel with the crankshaft that would cause the engine to rock outside of this plane (in the z-axis) are minimal. If your two flywheels are imbalanced with respect to each other, you'd get some. Of course, all listeroid manufacturers pride themselves on the extremely high quality and balance of their machines, so this is rarely an issue.
Then:
It doesn't matter how you mount/hang/swing that engine as it's still rotating and the forces are still present. Gyro forces only occur when when a flywheels axis is rotated. You can move a spinning flywheel without any gyro forces in all axes. It's only when you try and rotate the axis that gyro forces occur. As long as you don't get any rotation (turning) of the flywheel axis in the y/z planes (in our scenario, you can't rotate the axis in the x plane, it's just visible edge-on as a point in that plane).
This explains to me when I was watching that video of the loveson startup - it was very slowly creeping clockwise. One of his flywheels is slightly imbalanced compared to the other, causing a rocking moment in the y-z plane and rotating the flywheel axis, creating gyro forces which try and twist the machine around.
Following from that, it's very important to note that gyro forces all come from somewhere. Grossly simplifying gyro mechanics, one can say that a gyro is a thing that will convert forces 90 degrees. Twist a spinning flywheel about it's axis and it will want to lean. Lean a spinning wheel and it will want to twist. All the forces that make a gyro move are already applied somewhere - 90 degrees on another plane. If you take the loveson startup video, the forces are a rotation of the flywheel axis in the z-plane (front on to us in the video). These forces get translated to a clockwise movement of the base on the floor. So the forces are still there - instead of trying to rock the engine, they've been shifted to try and rotate the engine.
Finally (!) from all that, seeing as the crankshaft is already rotating, it doesn't really matter if the forces are applied in one plane or another - they're 90 degrees out, but the shaft rotates continuously past both planes anyway. So the gyro forces are just forces that would have been applied 90 degrees earlier/later anyway.
There. That's the problem I have with that bit. Can anyone sort it out for me? :D
(And a blackboard would be a really, really handy thing to have right now.)
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GI and Doug:
send me your email, i got a jpeg image of what i am talking about
i can send it, but don't have a clue how to post it here.
bob g
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i don't know if this will work, but i tried to learn how to do it in paint and then upload to a coppermine album
http://listerengine.com/coppermine/displayimage.php?album=lastup&cat=0&pos=0
bob g
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hooray,,, it looks like it worked!
now at least i can get a picture to help explain what i cannot relate in words effectively :)
bob g
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Thats what I thought you were talking about...
I was thinking about that at work last night, that and soil mechanics, weight of a cubic foot of concrete ect ect.
A lot of considerations when you build a foundation. Normaly I avoid most of the engineers where I work because they're all staff and find more work for me. Lately they avoid me because I grill them with questions about math, soil compression vibration ect ect.
Even people who have the mentall tool boxes fully equiped avoid this stuff.
Doug
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Well ,that does help to explain it a bit! :)
I still think the machine will try and rock around the CG as opposed to where it's mounted on the crankshaft centreline - that is , with the setup as you've drawn, you'll get some left-right movement of the frame instead of a true rocking action. Was trying to find a good real-world example, but it's a little hard. Probably the best way is to use a ruler, and hang it vertically from a bit of string tied off-centre. Jiggle the string back and forth and you'll find the pivot is at the CG. If you want it to pivot at where you tied the bit of string, you'd need to raise the CG.
It's easier to jiggle the string back and forth than to try and introduce a rocking action off-centre on the ruler. It's the same thing, just looking at it from the other way. If you move the string down the ruler until the rocking action stops, you've found the CG. At that point, if you rock the ruler back and forth, there's no movement of the pivot point.
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Gi:
one of the largest origins of the rocking component is from torque and antitorque, and that is centered not
at the center gravity, but at the crankshaft c/l
i have to go make some money right now (work)
but i was up half the night and have come up with more on this subject, that likely will raise more questions than it will answer
for some folks
bob g
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one of the largest origins of the rocking component is from torque and antitorque, and that is centered not
at the center gravity, but at the crankshaft c/l
Hmmm. Let me think about that for a bit.
If the CG is lower than the c/l, the extra mass below the c/l will be accelerated less from the torque/antitorque forces trying to rotate it compared to the lesser mass above the centreline. So the upper half of the engine will be accelerated more than the lower half (F=MA, as Guy_F is so fond of saying), making the top half move further than the bottom half in the same time frame, making the crankshaft want to move back and forth sort of horizontally a bit.
but i was up half the night and have come up with more on this subject, that likely will raise more questions than it will answer
Well I've been up ALL night - it's 3:15 am now (sigh) - but I haven't been thinking about this too much. Too many broken machines to keep me from thinking about anything much except for, "What time is it, and can I go home yet?" :D
(And after reading over my posts in this thread, I don't want them to sound like I'm attacking your ideas as such, I'm just trying to get a handle on it.)
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i have never felt attacked here, i invite critical thought.
to further explain my thinking:
if the engine rocking motion had it origins external to the engine, i think i would agree about going with the
center or gravity or the center of mass, and i would design accordingly, but
we are dealing with forces that center in the crank centerline, and
we want to limit the movement of the crankshaft in each of the 3 planes if possible by design,
and where we cannot limit the movement in a plane, we want to lmit its effect on the crankshaft/fywheel.
quite frankly i don't care if the valve cover moves +/- .25" or more, just as i dont really care whether the bottom of the crankcase does some part of the same.
at least personally :)
what i would like to limit though is the relative movement of the crankshaft
now for the fun part, that being the other forces or vibrations
i have seen reference here to 660 lbs of force being directed in a downward vector, presumably from ignition
and this force apparently provides for the up and down motion,,,, i disagree
i don't believe we have any down force from igntion or the power stroke, we have torque and antitorque, and we have the
transmission of the sound wave being vectored straight down into the mount, but not an actual 660 lb force.
so all we need is a donut style mount that islolates the transmission of sound from the engine thru the subframe,(rubber here) to the main frame
if the engine is fairly well balanced the mount will isolate the noise/sound vibration to the floor.
with a short profile donut style mount, there is more than sufficient surface contact to limit the for and aft movement in that plane, so i am not particuarly
concerned with movement here, likely be very small.
bob g
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I will preface this comment with the statement that "I haven't tried this yet." and in prior discussions elsewhere on the board various people have said it will/won't work but nobody has actually tried it. I tend to believe my own experiences as the canonical results of experiments, so I figure I'll try it and find out. It will be at least two months before I get a chance to spin them up, so anyone else having tested this method is welcome to chime in with actual results.
I have purchased two dynamic balance rings for truck tires from Centramatic. I purchased the heaviest versions available, which IIRC gives me about 8 pounds of mass which will automatically rotate to the position with least downward force (in other words, balancing out any imbalances in the rotational field.) I've had mounting plates made for installation directly on the crank. However, it may not work at all - the people at Centramatic simply said "Maybe, maybe not." for it to function in the way that I expect. The bad news might be that I discover my engine doesn't even require balancing. As soon as the chassis is complete, I'll let everyone know how that goes.
http://www.centramatic.com/
JT
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I think I see a flaw in your plan Bob:
Lets for a moment assume the 660 pounds for a min....
If you have that force directed down by ignition before its ever translated into torque you get an equaly up ward push from the engine and foundation. The rubber mount is going to let the engine compress between the block and give you more movement. Most of the energy stored in that rubber will be released into the block and the engine case. The block energy hopefuly will be dampened but the earth the engine case engery I don't know. This gets more complicated as the crank rotates threw the stroke and the presure drops.
Not all of this 660 force is directed up and down and everything changes as the angles between the force vectors, resultants andf torque changes. Way above my ability to finger out....
Uhm about all I can say it things jigle, the jigle won't be helped by rubber but will issolate some fo these forces in the engine case rather than disperse them in the ground.
Doug
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Doug:
you are correct that there is an equal force going up as there is down, all of the forces are contained between the head and the main brgs, at least as far as the up/down vector.
or rather i should say the vast majority of those forces,
the only things transmitted outside the block are
1. torque action
2. imbalance issue's with the engine
3. sound, vibration of ignition
also it is good to note that in 99.999% of concrete mounts they are still resilient as the ground has some give, some ground obviously has more give (damp clay)
if there were any real down force's they would abraid or work the concrete to death at the mount points.
my contension is basically if we had a steel ball, with a shaft welded on it
and cast the shaft into a concrete block and then set off a bomb withing the steel ball we would not have a very large down force if at all,
but we would transmit sound, noise or whatever you want to call it. certainly not a 600lb hammer blow
the mounts i referenced to are common mounts used for all sorts of hd truck engine's, most everyone uses them, are as common as dirt.
they last forever in very hostile environments, and handle torques in excess of 50 times that of a 6/1 comfortably.
with the diagram example i was only trying to illustrate how to limit the one component that is common to all engine's, that be torque and anti torque actions
we can limit that rocking action by simple design, leaving us with only
the up/down, and the side to side action
these rubber mounts are very dense, and only about 3/4" thick when torqued, the shear strength is such that the engine likely will not move fore and aft, or side to side but very little, leaving only the up and down component, which is very small in a well balanced engine to start with
the up/down, side to side, and fore/aft movement are far smaller components than that of the rocking component due to torque and antitorque action.
the up/down is going to be the sound transmission plane, so balanceing the engine should be done first to reduce what needs to be mitigated, whats left the rubber mounts will isolate quite well.
good mounts on a cat, cummings or whatever do a really nice job of isolating the noise/sound from the engine to the cab, but when one does wear out and fall out, the engines will damn sure rattle your teeth out.
if anything the truck mounts might be too stiff, and as such not isolate as well as a softer mount.
just like everything else in life, it is a comprimise. less movement more transmission, more movement better isolation.
i like the truck mounts because i can torque the thru bolt to fine tune to an acceptable comprimise between little movement and good isolation.
i still say that eliminating the rocking components effect on the crank/flywheel/brgs, is a huge step in the right direction
bob g
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No real argument here Bob....
My heads not so clear right now, I'm full of beer pork and venison....
But i didn't over do it!
I need to reflect on these ideas for while...
I looked at a set of cab mounts for Wagner truck and considered them as motor mounts. Yes they are large strong and look like they would last for ever as mounts for a Lister.
I need to look at a force vector diagram of an engine, even then I'm not sure I can get all the forces and resultants straight ( starting to get over my head )
Doug
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I got over my head the first couple of post a year ago!! Enough concrete works. ;D
I'll leave it up to the engineers to figure out how much is enough. Forty sack worked for ME!!
.........and I'm DONE. Ya'll are still calculating and figureing. ;D ;D
Merry Christmas!
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Its no longer a question of what works but a question of how and why...
I've learned so much about general machine theory that aplies to my day job its not realy a question of how much any more I want to be able to look at foundations and decide for myself things about them. There is a pair of 500 hp fans near my shop that vibrate a lot. They trip the monitors from time to time. More concrete is not he answere the foundations are wrong.
Doug
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Tater: you ole trouble maker you,, merry christmas to you too :)
some of us aren't in the position to live the dream yet,,, darn it,, some of us (me) have to live vicariously through folks like you.
as for the forever debate on this topic, for me it is an expanded learning thing, i like the theory.
and truth be known, i will probably use the 40 sacks in the end anyway,,, but maybe not :)
(actually i am only in this discussion to drive you concrete guys crazy... hehehe)
but seriously i have arrived at the formulae and tons of reference to how to specifically engineer a concrete base as well through all this
ongoing debate and hairpullin.
just figured i would fully investigate all the alternatives as well.
bob g
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These pictures suplied by Peter are of some Nordberg engines some using the mounting principle Bob sugests other mounted more like what we are doing withthe Listers now
http://www.oldengine.org/members/diesel/Nordberg/Nordberg3.htm
This Petter Atomic is sort of a cross between the two. I'd like to know where the CG is on this engine.
http://www.internalfire.com/albums/album30/tx.jpg
DOug
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This Petter Atomic is sort of a cross between the two. I'd like to know where the CG is on this engine.
I think it's somewhere in the next room :D
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I understand the wish to theorize...thats' how things get invented and how problems get solved.
I'm the type that would rather burn myself welding something together than burn out a 'mental math breaker' trying to calculate what would actually work better.
IF I were to build a moveable Lister mount it would be a 3x6 foot box made of ten inch channel iron. It would be made plain side out and braced for a heavy floor and rails for the engine.....and then poured full of concrete. THEN I'd figure out what's the best material to use between that and the floor to isolate any vibration.
Maybe surplus breast implants?? ???
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Jack that is probably the most inovative idea for mounts yet. And they're designed with "jigle factor"....
Dave I wish I had that Petter semi diesel in the next room
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well got the kid back to her mom today, and had the day to sit back and relax abit.
and well you know, i can't sit still for long without all this stuff rearing back up in the dark
recesses of my brain, so here i am again.
i question very strongly the assertion that there is a strong vertical component from ignition from the power pulse of a lister
the reason i question this is based on observation of a 12hp changfa, which is a horizonal or lay down cylinder, i have one sitting on a plywood skid in my
shop, and i can start and run it at idle ~1000rpm (by ear) and it will not move across the floor. this tells me that the force from ignition is contained within
the crankcase and the only thing being tranmitted to the mount are the torque and antitorque and the sound transmission thru the mount to the floor, which i
can feel in the house (much less so if the plywood skid is set upon a rubber mudflap)
so i am left to ponder if the changfa has no movement opposing the ignition forces, then why would there be a significant downward component from a lister?
if all one needs to control is movement on the crankshaft due to rocking, and we can handle that with design, and there is a very small or non significant vertical
component, then the rubber mounts such as described should provide the amount of isolation necessary to limit the transfer of sound/vibration of ignition to the
concrete floor.
i need someone to step up and argue opposition to this view
GuyF, you out there?
bob g
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A piston / cylinder / crankshaft arrangement is pretty much a closed system with respect to reciprocating movement getting out - all the combustion forces are balanced internally near ignition/TDC by the piston/conrod/bearings/cylinder/head.
As the gases expand and the piston moves down the cylinder some of the force is translated to rotation (and vice-versa on compression) which gives you the torque/antitorque pulses. The only reciprocating force escaping from the engine is the static imbalance between reciprocating and rotating masses - which is what, equal to a few kilos oscillating up and down the stroke at 650RPM?
One wonders if the traditional "thump" from concrete-bound listers is actually a rocking component of the concrete block getting sent out as opposed to the assumed vertical-lift-style thump. Hence the spec for a relatively deep block as opposed to a shallow slab floor with the same mass. The slab, with a rocking motion generated from the engine, would raise and lower the outer edges of the block a fair bit more and more easily transmit thumps than a block mostly underneath.
I wonder how that "V"- shaped rubber-lined concrete block would go if you set the v-edges to be perpendicular to the applied rocking force as much as possible.
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Bob was thinking about the inverted V in one of his posts.
I don't think the Asian horizontal diesel is a good analog for a Lister. Shorter stroke smaller lighter pistons and the Asian horizontal has two counter rotating ballance shafts. That much said some do not, I know of one that vibrated like the buisness end of an atomic jack hammer for about 12 hours before it self distructed. That was a bad engine from the start, but the owner said the vibrations and for aft shake was real trouble.
Doug
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GI:
i agree that the forces are contained, that i have always understood, but i have seen reference to some figures of a 660 lb down force from
ignition from a lister, i wonder now whether the reference did not understand that this force is not the force down on the mount,whether concrete or
whatever.
i do wonder though whether the thump that is transfered is mearly a sound transfer of ignition, and not a mechanical movement.
for intance, you can hold a rod up to your ear and tap it perpendicular to the rod axis on the other end and quite clearly get the transfer of sound
but no transfer of force. so if there is no transfer of force then rubber should dampen the sound transmission.
so we seem to agree that perhaps the rocking component is the primary transmission component to the ground.
so it would follow anything we can do to reduce the rocking component or control it thru design the less there is to transmitt motion
and thump to the concrete floor and other structural elements.
of course you are correct that if we have any static, and particularly dynamic balance issues they will certainly be transmitted to the base as well.
which lends validity to getting the engine as well balanced if not dynamically at least statically. the better the balance the less these unbalanced
forces come into play obviously.
i am not sure that the cube base would work better than a slab base (concrete), on the one hand any rocking would lift a longer base further, but it would take much
more torque to do so (from a leverage standpoint)
"I wonder how that "V"- shaped rubber-lined concrete block would go if you set the v-edges to be perpendicular to the applied rocking force as much as possible."
now that is an interesting concept "geometrically", the length of the block would then dictate the angle of the V shaped base, to keep the sides of the V perpendicalar
to the rocking radius. i will have to think about that one.
Doug:
good point as to the counter rotating shafts, they work together to help to balance the rotatating assembly, but
they cannot work to overcome any forces of ignition because those are not static, rather those forces change with loading
also i do have a non countershaft changfa, and it does not seem to exhibit motion in opposition to the piston downforce either...
onward:
what i do find is a thump transmission from the changfa sitting flat on the concrete slab, i think i will run a few crude experiments to
see if i can isolate the "thump" or mitigate it.
basically i will just pickup the assy and sit it down on a group of rubber isolators, and see if the thump is mitigated, if so
then i think the next step will be to build a "cradle style subframe" to center the rocking element on the crank c/l
and then mount the subframe on rubber mounts, and do some testing.
i guess the beauty of this forum is the diversity of approaches, it damn sure would be time consuming and cost mega bucks to design, build and
test each an every approach.
because i have the changfa on the floor and all the related parts and stuff to assemble it, i think i will now go forward and try the cradle method or resilient mounting.
if the results are what i anticipate, then perhaps the next will be the same design of mount with a 25/2 lister.
we all know that 2 tons of concrete works, and some folks have done well with a ton of crete,
we also know there are some that have had good results on large wood beams,
i guess i will go the mile and do the cradle/resilient mount, and see what the result is.
bob g
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GI:
i just ran the geometry, and it would appear that the angle would change (in an effort to keeping perpendicular) with the length of the concrete block
as it applies to a V mount.
looks to be an interesting mounting system, with enough mass so as to be very hard for the engine to lift either from rocking or vertical lift(balance issues)
would be interesting to give it a try, but sadly an expensive experiment, i think i would want to try and prove out the concept a bit more before
i expended the effort to casting a V pocket in the floor, and then rubber lineing the sides and casting the machine base.
one thing i am sure of the quality of the subsoil would have no real effect on the outcome.
might be an interesting alternative for those on questionable soils, damp or wet clay, etc.
in the future i plan on a shop, so i would probably try this mounting system in that environment.
bob g
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Well I guess now that I have some putter time for a few day I can get serious about the Petter and try and catch up with you guys.
I think I like the Idea Bob has about mount. I don't need any more discussion on th subject I'm going to try it your way Bob. And I think the added concrete will give me some piece of mind when I try and build a guard out of some arched heavy plate to cover the top half of my fly wheel. I think this might work out nicely as a way to make the animal a little safer to be around as well.
Here's another Nordberg picture from Peter that makes me think you maye be onto something
http://www.oldengine.org/members/diesel/Nordberg/Nordberg0531.htm
Notice the way the engine sits in the foundation and how they have shown the CG at the center line of the crank.
Doug
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well got the kid back to her mom today, and had the day to sit back and relax abit.
and well you know, i can't sit still for long without all this stuff rearing back up in the dark
recesses of my brain, so here i am again.
i question very strongly the assertion that there is a strong vertical component from ignition from the power pulse of a lister
the reason i question this is based on observation of a 12hp changfa, which is a horizonal or lay down cylinder, i have one sitting on a plywood skid in my
shop, and i can start and run it at idle ~1000rpm (by ear) and it will not move across the floor. this tells me that the force from ignition is contained within
the crankcase and the only thing being tranmitted to the mount are the torque and antitorque and the sound transmission thru the mount to the floor, which i
can feel in the house (much less so if the plywood skid is set upon a rubber mudflap)
so i am left to ponder if the changfa has no movement opposing the ignition forces, then why would there be a significant downward component from a lister?
if all one needs to control is movement on the crankshaft due to rocking, and we can handle that with design, and there is a very small or non significant vertical
component, then the rubber mounts such as described should provide the amount of isolation necessary to limit the transfer of sound/vibration of ignition to the
concrete floor.
i need someone to step up and argue opposition to this view
GuyF, you out there?
bob g
Got to go off at a tangent, cos you're still worrying this particular bone, and still doing the same things.
In another thread people are talking about flicker due to RPM variations over the 4 stroke cycle
there are 2, and only 2, ways to deal with this.
1/ massive flywheels for massive inertia
2/ massive amounts of cylinders arranged so firing strokes are equally spaced around 720 degrees of crankshaft rotation.
both things are aiming for the smoothness of an electric motor, in some applications this is more desireable than others.
a 4 cylinder motor doing 2000 rpm produces the same number of power strokes as a 1 cylinder motor doing 8000 rpm, but the 4 pot will be far smoother
aircraft propellers are complex things, the aerodynamics work best if driven by an electric motor type of power source, you don't want any variations in prop rpm, it really screws the efficiency, and you can't use massive flywheels in an aircraft, so pratt & whitney made an 18 cylinder radial, very smooth, the other popular configurations were 12 and 16 cylinder, vee and h formations, get the crank / cam timings right and you end up with a suprisingly smooth engine at anything much over tickover
you get a similar thing in outboard motors, a 2 stroke v 6 is remarkably smooth, and like the aircraft analogy, you simply don't get high power any way other than multi cylinder.
making an engine, as in manufacturing, has a cost per bore, it costs pretty much the same to build an 850 cc 4 pot mini engine as a 2.2 litre 4 pot vauxhall engine, given that both use similar design materials, so it is cheaper for the builder to get the desired bhp from a big 4 than from a smaller v6 or v6 or straight 6, or a v8, if they don't, it is because some other consideration vastly overcomes the cost of construction one.
my japanese motorcycle has a 1 litre v2 engine, lot cheaper to make per engine than a 1 litre straight 4, but if you are marketing a crotch rocket it blows donkeys.
===========================
A lister cs 6/1 is a lister cs 6/1, there is nothing to be learned about a lister cs 6/1 from a changfa, petter, ruggerini, or any one of a million other engines out there, they are not the same and the differences more than make up for any useful analogies you can draw.
A listeroid is NOT a lister, a point I have always made and always stressed the fact that I have never even seen a listeroid, they are allegedly copies, but enough things are different (this is a really important point) even though they are apparently 99% the same DNA, that my extensive knowledge of listers cannot be safely applied to any listeroid..... I touched on this yonks ago, "cast iron" for example is about as accurate as "human being", it equally describes the iron man decathlete and the bed ridden cripple, TRBs are not plains, and so on and so forth.
===========================
for a gen set you want SMOOTH power delivery, so you have lister copies, ok....
my start-o-matic has two 300 lb flywheels spinning at 650 rpm, and about 150 lb flywheel on the head spinning at 1500 rpm (50 Hz set) there is no noticeable flicker.
"do the math" is a phrase I often use, people pay ZERO attention to this.
The "common sense" belief held on here is that the 150 lb listeroid spoked flywheels are what makes the listeroid pull gen head loads above it's apparent bhp punching weight.
go calculate the current / vs time graph for a direct on line 3 hp electric motor starting up, lot of energy wow, but until and unless you do the math, and have a CALCULATED NUMBER for this energy, and do the math and have a CALCULATED NUMBER for the amount of energy (those vectors and centre of mass equations again from the concrete block perpetual threads) required for everything except the useful power part of the power stroke of the 4 stroke cycle, and a CALCULATED NUMBER for the amount of energy stored in the flywheels at various RPM, you have literally no idea how the three figures (flywheel inertia, 4 stroke cycle entropy, elec motor start load) relate to each other.
I have tried and tried and tried to get people to at least attempt the math, even going so far as combustion pressure x cylinder area x effective crank radius (at that point in cycle) = torque, and of course ALL torque output at crankshaft is equal and opposite loaded against the cylinder walls, sideways, and how does this equate to 45-50 ft-lb produced by the engine.
people just grab the bits they want out of that and carry on running in the same direction as before, now brandishing this new "proof" or "fact", utterly missing the point.
=======================================================
CS 6/1 is a single cylinder 1400 odd cc diesel engine, medium speed, vertical orientation, blah blah blah.
there is FUCK ALL about how a radial nordberg or a straight 6 sulzer or a pancake arrow is mounted that is ANY FUCKING USE whatsoever, with the SOLE EXCEPTION of the one bit NOBODY WANTS TO DEAL WITH.
That one bit is the math...... the math applies to them all........
Bob, you don't believe there is a strong vertical component to a lister running, based on your observations of things that aren't listers running.
4 large beams set parallel and vertically, so you end up with a lister riding a cage like a lift, can't rotate or rock, can only go up and down with power pulses, say the set + cage weighs 2500 lbs, we lie you on the concrete ground, lower the cage onto your chest, with a 2500 lb spring to exactly balance it, and maybe 1 lb weight on your chest, and the deal is we chuck the lister on full song and full load.
If I was bill gates I could afford to fly over there and build such a rig, and fly the whole forum in to observe.
If I was bill gates I could afford to make a bet (to cover the cost of the experiment) which would have zero takers that there is no fucking way bob is going to lie on the ground without first seeing it tested on maybe a watermelon
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This is the problem I have with ALL these forums, whether they be about listers, or motorcycles, classic cars, you name it.
Shooting the shit in forums like these is not the same as shooting the shit anywhere in real life.
Here, those who want to believe that there is some sort of answer than does not require them to keep on running in the same direction they have been all the way through, simply band together and start selecting the bits that suit them and support their belief.
You'll get others, like mr belk, who says basically "fuck it, the concrete block works 110%"
so the naysayers come back, what if'n yer engin ain't balanced real good? well what if you get sump dilution and a runaway, what if you've been using the flywheels as an anvil, concrete block isn't an antidote for being an asshole, or a cheapskate, or trying to get somewhere that "if I was going there I wouldn't start from here"
concrete block is no more than one part of an integrated system, that if they are ALL done diligently, you end up with a safe and reliable and trustworthy piece of kit.
Ask mr belk to build you a handgun based on a win 456, or a huntin rifle based on 22 short rim, hell, back in the days the ruger mini 14 in stainless and 223 was a popular gun around central africa with the mercs, tough, reliable, flat trajectory, accurate, and you could carry a reasonable amount of ammo, but 303 and 308 weren't deflected by the bush in between gun and target, so rugers were available cheap, fabrique nationale fns were sought after
Listeroid ain't a lister, but, lister never made a gen set with spoked flywheels, so you're right in a "if I was going there I wouldn't start from here" place before you even start, couple of dudes are making heavy alternator pulleys, which help, except the alternator head ain't designed to carry heavy pulleys, nobody I have heard of has taken the simple route to address this by ordering double flywheels, listeroids with plain mains will carry double spoked flywheels easy enough, YMMV with TRBs
Lister determined that 600 lb of crankshaft flywheel was enough, if they could have got away with 300 lb of crankshaft flywheel they would have.
You can't add cylinders. but you can add flywheel mass, hell, you could direct couple 6000 lbs of flywheel on separate mounts if you so desired
those of you with 150 lb spoked flywheels, I dare you to remove one flywheel and then fire the bitch up, on a crate or on flexible mounts if you like, have a change of trousers handy, and maybe a spare crankshaft
the forces generated inside the engine are the same, flywheels make engines smooth because they are a store of rotational inertia, but they have a limited effect on all other vectors.
oh, and puhleese don't talk about torque and anti torque, you can't have anti torque any more than you can have anti voltage or anti money (anti torque devices such as a helicopter tail rotor do not develop anti torque)
torque and vectors
- (minus) 5 VDC is not anti voltage
================================
bottom line, if you want a lightweight semi mobile generator, what the fuck are you buying a listeroid for?
the world is full of lightweight semi mobile generators and lighting plants, based around direct coupled 1500 rpm air cooler lister twins and triples.
In closing, my real concerns about these sorts of conversations, you end up with idiots thinking that because so many people are discussing how to make lightweight semi mobile generators out of listeroids, that it is possible and advisable, and of course safe, the blind lead the blind and next thing you know someone is killed.
Now i see there are pictures of a broken flywheel, insufficient data as usual, but the point being that if I had warned about breaking flywheels (as a matter of fact I did) through ignorance of the math involved and shifting the centre of mass outside the engine to shift the vectors I would have been told, as I was, that I was talking out of my ass, because at listeroid rpm you are never even approaching much less exceeding cast iron flywheel safe speeds.
neverthess, there are now confirmed pictures of a broken flywheeel, and IT DID NOT EXPLODE DUE TO OVER SPEED, those are fatigue flaws you can see in the picture, IT DID NOT LET GO WHEN STESS WAS AT ITS MAXIMUM at rated running RPM, it let go when stress was negligible, so its fatigue, not bursting force.
as long as you have a hole in your ass, even with a million dollars worth of high tech equipment, you can't spin a flywheel up to bursting speed and then bring it down to stop and avoid a flywheel explosion, can't be done, like trying to hit a glass with a hammer hard enough to break the glass but somehow stopping the blow from breaking the glass after the glass starts breaking, or breaking a bolt under tension.
===============================================
I have people around my lister, but it is an original, and I am cautious.
If I had a listeroid it would be stripped and blueprinted and bolted to concrete, if it was driving a gen head I'd have ordered a plain bearing bitch and doubled the flywheels. it would be caged and no fucker would go near it till I had at least 20k hours accumulated knowledge.
The ENTIRE aftermarket car parts business is based upon people who bought a chevelle and want a vette, the same shit is going down here, motorcycle forums are full of weekend riders who probably don't even have 100k miles in their lifetime on 2 wheels and who never went more than 500 miles from home, but they are chasing things like some mod will bring them to being that much closer to being randy mamola, or michael schumaker, or ik brunel, or ontario hydro.
=====================================
Lets assume I am 100% responsible for mr belk going concrete block, if that were so then I am 100% responsible for the consequences.
Lets assume his motor suffers a catastrophic failure (and no noob apprentice fantasy backed by zero math about the concrete mounting somehow making an imbalanced engine more prone to failure) of some sort.
Whatever the nature of that catastrophic failure, it will be lessened by being bolted to a concrete block, not just the likelihood of such a failure, but also the conseqences of such a failure, so me, being hypothetically 100% responsible, am on a winner, as much as anyone can be in such circumstances.
make no mistake, one of these days someone is going to report in this forum that someone has been maimed or killed by a listeroid, and I will be you anything you like, my entire worldly goods, that it will be attributable to people thinking they know best, when they don't, and ignoring the "mantra" that I "preach". Of course WHEN it happens it will be churlish to point this out and doing so will earn me nothing but condemnation for my lack of humanity and empathy.
Mr belk using a concrete block doesn't mean it won't be him, it does mean he is NOT creating one of those links in the chain of events that leads up to such "accidents" as discussed in other threads elsewhere, and spending all day NOT creating these links is what safety and reliability are all about.
What you people are doing is not safety, it is safety theater / theatre, you wish to have the appearance of due diligence, without the time, expense, consequences and limitations of it.
Please read this carefully.
Windows Vista is coming out, they are saying it is the most secure windows ever, however, since it has NEVER BEEN TESTED in the real world, it cannot be secure, not even one iota.
A system can only be deemed secure after it has been exposed to the real world for decades and trillions of man hours, a split pin and drilled nut is a known, tried, tested and secure way of fastening a nut, amongst its many advantages is the fact that visual inspection will give many clues as to ongoing durability, it has its downsides, takes time to install etc, but they are worth it.
Now lets say I invent and design a new system of doing the same job. Until it is in as widespread use as the old system, and has been for decades, any claims that I make about the relative security of my system vs the old system are purest fantasy.
Nylock nuts were such an innovation, they were the answer to everything, except you still don't find them used in real security to hold wheels on to axles.
You alternative (eg everything except the concrete block) mounting systems are just the same, except nobody designing these alternatives is a BEng with a millions dollars or finite element modelling thrown at it, and this is ON TOP OF and COMPOUNDING the fact that you are using known inferior copies of listers with zero effective quality control, ZERO EFFECTIVE QUALITY CONTROL.
Bob and others, until and unless you are willing to stop your dead set determination to go in a given direction of your own choosing and genuinely re-examine the entire subject from basic premises you are never going to get this, because your real priority is getting "there" from "here", and nobody is allowed to say that if I was going there I would not go from here, and if that means all the time money and effort I spend getting here in the first place is wasted, that is tough.
I see welded frames, comments like "my welds won't break", like their welds are something unique on the planet, EVERY weld will break, all these welded frames ALL lack filleted radius plates and triangulation, every last one of them. (not quite true, there is one that looks like it was designed by an engineer)
I have shown you pictures of the underside of the lister s-o-m cast base, nobody wants to attempt to duplicate it mechanically in steel, cos steel costs dollars eh.
And that is the bottom line, trying to do a 100 dollar job for ten bucks and change, without realising the ONLY area you can save bucks over industry is labour costs, WITH THE PROVISO THAT YOUR LABOUR IS OF EQUAL STANDARD TO A TRADESMAN.
That is NOT a given.
All these mounting threads are the same, you can lead a horse to water....
Nobody here wants to drink, cos it costs dollars and time and effort. "good enough" rules the day, even though those declaring something "Good enough" aren't qualified in that field.
Matey in oz, with someone adjusting the pressure release valve, that is the same mentality you get here, that bloke "thought" he knew what he was doing too, he "thought" it was safe enough, and he "thought" it would produce the desired results.
What SHOULD happen there, but won't is security, what will happen is security theater.
Security theater is sacking the guy.
Security is making it known that ANYONE who is an operator who so much as picks up a spanner gets sacked on the spot.
Security theater just ensures that for a few years no one operating those particular machines messes with them.
Security ensures that no one who is not qualified and experiences enough ever touches any machine.
Security theater is fast and cheap and demonstrates due diligence which satisfies the insurance company and regulators
Security is ongoing and costs money, but over time saves money and increases reliability and productivity.
==================================
People, this is not the first time in my life I have been somewhere and said "one day you fuckers are going to kill someone"
Some times it has come true in mere weeks, sometimes it took months, but so far, unfortunately, I have yet to be wrong.
I have learned the smell of people acting in such a way as to create the chain of events that eventually gets classified as an "accident"
that's all for now, merry yule and a happy new year to you all
-
GuyF:
welcome back you cranky old bastard :)
you accuse me of taking from the discussion what i want from it, and the case can certainly be made that you do the same.
i suppose to some extent that is human nature.
i would most certainly like to clear the air abit, and restate my position.
1. we dont have 300lb flywheels, at least not yet, and we all know the attractive nature of having them. restating this fact has little to add to the
conversation.
also i might add that an ST head is not a SOM genhead, there is a harmonic component that some folks are trying to work around and eliminate.
this harmonic component has an effect on the flicker for some folks.
2. we don't have many cylinders we have one and in some cases two, so the discertation on the pro's and con's of multi cylinder engine's along with their
manufacturing costs is of what use to the discussion?
3. i dont think anyone is contemplating putting their engine on an airplane, so all the talk of props and vibrations is interesting but of little use.
4. you say a lister is not a listeroid, or rather visa versa, and that there is nothing to be learned from a changfa etc that can be applied to a lister, fine!
90% of us will never own a pure bred lister, we have what we have, and that is a listeroid. if a listeroid is not a lister, how pray tell am i not to extrapolate info
from a changfa and apply it to a listeroid? is a listeroid now a lister for this segment of the arguement?
5. again i do "not" have to do any math to accept the fact that heavier flywheels are what one wants to smooth out power pulses, further
the "math" is only as good as the "input" information is. but you knew that, that is why you never put up any useful equations. for the math to be of
any real use, one is going to have to arrive at useful numbers, and those numbers are not going to come from a garage, at least not the typimcal shop.
these numbers will come from a test cell, complete with all instrumentation, a dyno, etc.
6. lets talk about concrete blocks for a minute, i have researched this one to death, i would also agree that it is a very viable method of mounting a stationary
engine, and it works. Of course we should do the "MATH", but alas you don't come up with any useful information, no fucking formulae, no links to solid engineering.
I might add the following,,,
a. i have supported the use of concrete
b. i have arrived at a formulae to describe the lister 6/1 concrete block of 1938
c. i have posted links to engineering of concrete bases
d. i don't think there is anyone here that is argueing against their use, and
e. a listeroid is not a lister, in most cases a listeroid is not nearly as finely balanced as your lister
7. vertical component, no i do not believe there is a strong vertical component, period, further the only vertical component will be related only
to engine balance.
i defy you to defend that there is by simply stating "do the math", i say screw you and the horse you road in on for this one. this one you are going
to have to come up with something concrete, some specific math or reference to how you arrive at that. if there was a strong vertical component
the concrete junction at the mounting bolts would abraid in short order.
8. torque and antitorque, rather i should have stated torque and counter torque, certainly you accept the existance of countertorque?
where i am relating the torque and countertorque is how it affects the engine case, and yes there is a torque and countertorque happening throughout
the 720 degree of rotation. do we really need to debate this one?
9. Safety, from the safefty stantpoint i have to agree with you. but in reality, if you wanna be safe don't buy and install any mechanical equipment.
and yes sadly there will be those that bolt their engines down to a piece of cardboard, and baling wire welds that look like something even a goose would be
ashamed of.
10. a disclaimer
i am not promoting one type of mounting system over another, i am only exploring other options in doing so.
there are numerous safty concerns that should not be discounted by anyone. should you decide to purchase and assemble
any piece of equipment, you will accept the responciblity of the outcome. so do you research, plan well, and provide all measure of
safety.
11. on a personal note:
GuyF, i know your heart is in the right place, but you come off as though a spoiled rich kid coming into the sandbox.
sometimes it takes me a while to understand what you are driving at.
i think the day has come that i am going to call you out, and ask you to support your assertions, with the math and equations that
you so frequently tell us to do. recently i joined a group of mechanical engineers, and posed the question to them, funny thing their responces.
they either lead me to good solid info with the math and equations, or they don't say a thing. hmmm now that is useful.
you seem to be a likeable if not crotchedy ole bloke, that i might very well sit down and have a brew with one day, but damn you
can be a pain in the ass some days :)
i welcome your responce and if you wanna poke me in the eye have at it.
bob g
-
added note*
why am i so intent on exploring other options in mounting an engine?
the piece of property i have is located in central kansas, kansas was once an inland sea
the paricular area of the state my property is locating is has a bedrock of limestone.
this bedrock transmitts vibration and shocks in some cases many miles, the rock quarry outside of town, when blasting each day
at 5 pm, sends shocks thru the whole town and for miles around thru the bed rock, the quarry is a mile out of town
the railroad also transmits through the bedrock, as do trucks on the highway and the rumble strips at the intersections
i don't know why this rock (limestone) is different than other bedrock in transmission of vibration and shocks, other than there are
vast aquafir's underneeth.
so yes i am exploring alternative methods of mounting, and trying to arrive at soundly engineered ways of doing so.
i am not simply trying to scab together something expedient or cheap without regard to sound engineering practices.
if anyone wants to constructively debate the issue please feel free to do so, but my patience is getting thin with those that
simply want to sit back and make offhanded observations and blurr the discussion.
simply stated, if you can add to the debate, please do so, if you just wanna pop in and kick sand, obfuscate, and tell me to do the math without providing
equations, concepts and a drawing or two, then "take a hike"
bob g
-
GuyF:
welcome back you cranky old bastard :)
you accuse me of taking from the discussion what i want from it, and the case can certainly be made that you do the same.
i suppose to some extent that is human nature.
quite right, but what are our goals, they are not the same.
i would most certainly like to clear the air abit, and restate my position.
1. we dont have 300lb flywheels, at least not yet, and we all know the attractive nature of having them. restating this fact has little to add to the
conversation.
also i might add that an ST head is not a SOM genhead, there is a harmonic component that some folks are trying to work around and eliminate.
this harmonic component has an effect on the flicker for some folks.
There is nothing magic about s-o-m flywheels, 2 x 150 lb flywheels (of the same diameter) per side works exactly the same as 1 x 300 lb flywheel per side (on a stationary engine not subject to precessive forces etc)
Just because you don't have s-o-m style flywheels means precisely nothing as to why you don't have s-o-m mass of flywheel
2. we don't have many cylinders we have one and in some cases two, so the discertation on the pro's and con's of multi cylinder engine's along with their
manufacturing costs is of what use to the discussion?
I'm trying to illustrate the fallacy of comparing apples to oranges when it suits you, and when comparing only the bits that suit you, eg size, shape, mass, while utterly neglecting the differences, which are more important, because it doesn't suit your argument.
in engineering you can't pick and choose the bits that suit you.
3. i dont think anyone is contemplating putting their engine on an airplane, so all the talk of props and vibrations is interesting but of little use.
It's another illustration of the importance of application, and comparing ALL aspects of apples to oranges, not just the bits that suit you.
EVERY time, without fail, that I try to do this, you simply dismiss it as irellevant.
it is MOST relevant, but it leads inevitably to answers nobody likes.
4. you say a lister is not a listeroid, or rather visa versa, and that there is nothing to be learned from a changfa etc that can be applied to a lister, fine!
90% of us will never own a pure bred lister, we have what we have, and that is a listeroid. if a listeroid is not a lister, how pray tell am i not to extrapolate info
from a changfa and apply it to a listeroid? is a listeroid now a lister for this segment of the arguement?
Your argument holds no water.
a brand a listeroid will tell you something useful about a brand b listeroid, just as a lister will tell you something useful about a listeroid.
the caveat is SOMETHING USEFUL, it ain't a bible, just a starting place, picking other engines is risible, it takes you back to the apple and orange, and least lister / listeroid is comparing two apples of approximately the same breed
5. again i do "not" have to do any math to accept the fact that heavier flywheels are what one wants to smooth out power pulses, further
the "math" is only as good as the "input" information is. but you knew that, that is why you never put up any useful equations. for the math to be of
any real use, one is going to have to arrive at useful numbers, and those numbers are not going to come from a garage, at least not the typimcal shop.
these numbers will come from a test cell, complete with all instrumentation, a dyno, etc.
How many times, I don't put up the complete and precise calculations because it is not my job to do so, I choose not to, I have other things I would rather do with my time.
NEVER do I say you must simply accept that I am correct, without fail I give enough information so that those who choose to work it out can source the information they require.
NOBODY, but NOBODY, has ever even ATTEMPTED to do this.
nuff said
6. lets talk about concrete blocks for a minute, i have researched this one to death, i would also agree that it is a very viable method of mounting a stationary
engine, and it works. Of course we should do the "MATH", but alas you don't come up with any useful information, no fucking formulae, no links to solid engineering.
Like I keep saying, not my job, and not my job because 100+ years of stationary engine installations the world over go with the concrete block.
slice it any way you want, nobody has addressed this fact adequately, cos nobody likes the answers.
I might add the following,,,
a. i have supported the use of concrete
b. i have arrived at a formulae to describe the lister 6/1 concrete block of 1938
c. i have posted links to engineering of concrete bases
d. i don't think there is anyone here that is argueing against their use, and
e. a listeroid is not a lister, in most cases a listeroid is not nearly as finely balanced as your lister
irellevances.
poorly balanced listeroid v finely balanced lister is a straw man argument.
we have precisely ZERO evidence that listers were better balanced than listeroids.
the ONLY evidence we have is that listeroid QA is non existent, re twins with different weight rods and pistons.
This is a QA issue, not a design issue or a balance issue.
the ONLY thing we can infer from this is that we cannot with any safety assume that any two listeroids are even vaguely similar.
7. vertical component, no i do not believe there is a strong vertical component, period, further the only vertical component will be related only
to engine balance.
your belief is irrelevant
it does what it does, based on known physics and known math.
NOBODY here is prepared to do the math
NOBODY here is prepared to do empirical measurements and analysis.
so you said it right, you "believe"
look up belief in a dictionary, an opinion that is not supported by fact, an unprovable (not unproven) theorem, an act of faith.
not engineering
i defy you to defend that there is by simply stating "do the math", i say screw you and the horse you road in on for this one. this one you are going
to have to come up with something concrete, some specific math or reference to how you arrive at that.
no, I am not, not my job
it is not me who is going against 100% of engineering knowledge and 100% of physics knowledge
if there was a strong vertical component
the concrete junction at the mounting bolts would abraid in short order.
ludicrous, cast iron is brittle, if your statement held any worth you could as easily claim that the cast iron junction at the base of the cylinder would abrade in short order.
as indeed it would, of the cylinder were left slack, happened to enough harley motors, first the base gasket went then the cylinder sheared off, or first the bing end wore on the bridged con rod and then the cylinder sheared off.
it takes movement in appreciable amounts.
lister
base
grout
concrete
but your argument requires
listeroid
concrete
null argument
8. torque and antitorque, rather i should have stated torque and counter torque, certainly you accept the existance of countertorque?
where i am relating the torque and countertorque is how it affects the engine case, and yes there is a torque and countertorque happening throughout
the 720 degree of rotation. do we really need to debate this one?
apparently we do, because nobody appears to grasp the implications, because they end up thinking a single cylinder vertical diesel engine of 1400 odd cc capacity will have no significant vertical moment of force demonstrated outside of the engine block...
9. Safety, from the safefty stantpoint i have to agree with you. but in reality, if you wanna be safe don't buy and install any mechanical equipment.
and yes sadly there will be those that bolt their engines down to a piece of cardboard, and baling wire welds that look like something even a goose would be
ashamed of.
another straw man argument
safety does not = stay at home in bed and do nothing
safety theater and safety are two different things.
10. a disclaimer
i am not promoting one type of mounting system over another, i am only exploring other options in doing so.
there are numerous safty concerns that should not be discounted by anyone. should you decide to purchase and assemble
any piece of equipment, you will accept the responciblity of the outcome. so do you research, plan well, and provide all measure of
safety.
11. on a personal note:
GuyF, i know your heart is in the right place, but you come off as though a spoiled rich kid coming into the sandbox.
sometimes it takes me a while to understand what you are driving at.
spoiled rich kid?
I live on, sorry, _we_ live on about 10k bucks per annum, after housing, including everything else, heat, light, car, insurance, clothes, pooters, smokes, food, everything.
I _used_ to earn somewhat more than a small fortune every year, I live this way now cos I choose to, fuck the rat race.
I could go into a long and detailed array about how to live life as a technological hermit, living off the "obsolete" scrap of others, from the free obsolete amd 64 bit 3800 cpu in the box I am typing on down
I've wanted a sherline (www.sherline.com) cnc lathe and mill for about 2 years now, I can build either from components, easy peasy, have the contracts and the ability, but I can't build with the repeatable accuracy and flexibility and utility for less money than buying new from sherline, economies of scale
it is partly BECAUSE I am a techno hermit that I am like this, I KNOW where the fat is that can be trimmed, and where the meat and potatoes are.
the point you lot appear to fail to understand is that it costs x amount to build a proper machine to do a job, whether that x amount represents 5% of your disposable salary or 4 years total income is irellevant.
building down to a price gives you your disposable suitcase generators that will not produce their rated load even when new, the ONLY people who think it is a proper generator are the idiots who buy them, the marketing droids know its a piece of crap.
a listeroid is 400 bucks on the dock cos THERE IS ABSOLUTELY ZERO QUALITY CONTROL, you could build listeroids to the same spec with american labour and american wages for 600 bucks a pop tops (forget the legal aspect)
simply mandating lister grade cast iron throughout, even in india, will bring each unit to 1500 bucks or more, minimum.
======================
don't get me wrong, I'm not being poor mouthed, I choose to live this way and am very content.
I was lucky, my start-o-matic came about at the same time I had the 300 quid spare, I got a bargain and I know it, give me 1750 uk pounds as it sits and I'll sell it to you, that's how much of a bargain I got, however, if you all clubbed togther and GAVE me a free listeroid, I could not afford to keep it as anything except a garden ornament.
there ain't no such thing as a free lunch, and that total lack of quality control inevitably means the end user is going to pick up the tab.
I did not buy my current car because it cost 199 pounds.
I bought my current car because it was 100% mechanically and electrically operable safely, it is 100% reliable, and it does 60+ miles per (imperial) gallon of diesel, and at 199 pounds I could also afford to purchase it.
I could lay my hand on enough cash to buy a new mercedes diesel tomorrow, but that isn't the same thing as being able to afford it.
spoiled rich kid?
shit, I can't afford to play the games you lot are playing. I'm not rich enough to maim or kill someone and cut a cheque to make it all right
i think the day has come that i am going to call you out, and ask you to support your assertions, with the math and equations that
you so frequently tell us to do. recently i joined a group of mechanical engineers, and posed the question to them, funny thing their responces.
they either lead me to good solid info with the math and equations, or they don't say a thing. hmmm now that is useful.
you seem to be a likeable if not crotchedy ole bloke, that i might very well sit down and have a brew with one day, but damn you
can be a pain in the ass some days :)
like I said, not my job
besides which I'm not crotechety, or cynical, I'm experienced.
I wouldn't waste my time trying to show someone when I know damn well that person doesn't want the truth, they want a set of answers that are acceptable to them, so that they can go ahead and do the thing they already decided to do anyway.
that is the not my job bit, it is not my job to help you to support whatever belief system or world view you currently hold.
that job is called marketing, or PR, which used to be known as propoganda.
i welcome your responce and if you wanna poke me in the eye have at it.
bob g
I don't wanna poke you in the eye, make you see the light, or anything else, I am quite happy for you to go on believing anything you like, not my job to change you.
Fact is, such things work to well known and understood rules, and there is no route to understanding and mastery that avoids first accepting that, and then studying it.
The FACT is that when you drop a lump of steel it does not fall towards the ground, the ground and it fall towards each other, but the earth is massive and moves infinitesimal amounts, and we are macroscopic and stood on the earth anyway, so we assume the earth doesn't move....
just like people welding frames with no filleted radius plates and no triangulation, they assume nothing is going to move under the forces imposed by the lister, even though they KNOW intellectually the steel frame MUST show some movement, because it is small and invisible people assume it is negigible, it ain't, and welds eventually crack..... no boilermaker would ever claim to be able to routinely make a weld that never cracked or gave, but boilermakers have forgotten more about welding than I am ever likely to know
3 foot long side rail for a frame, 2 foot long cross brace for a frame, assume the 3 foot long beam has 1 thou of movement due to the cyclic loads put on it, use pythagoras and tell me how much the right angle weld flexes with every cycle.
always avoid using welds to take loads, same as always avoid using bolts to take loads, welds are fasteners same as bolts.
with proper triangulation and radiused fillet plates you can bolt or weld a frame and the stresses are absorbed in the structure, instead of working to fatigue the fastener, whether that fastener is a weld or a bolt, but hey, this is exactly the same argument as the concrete block, and that went down like a lead balloon innit.
-
added note*
why am i so intent on exploring other options in mounting an engine?
the piece of property i have is located in central kansas, kansas was once an inland sea
the paricular area of the state my property is locating is has a bedrock of limestone.
this bedrock transmitts vibration and shocks in some cases many miles, the rock quarry outside of town, when blasting each day
at 5 pm, sends shocks thru the whole town and for miles around thru the bed rock, the quarry is a mile out of town
the railroad also transmits through the bedrock, as do trucks on the highway and the rumble strips at the intersections
i don't know why this rock (limestone) is different than other bedrock in transmission of vibration and shocks, other than there are
vast aquafir's underneeth.
so yes i am exploring alternative methods of mounting, and trying to arrive at soundly engineered ways of doing so.
i am not simply trying to scab together something expedient or cheap without regard to sound engineering practices.
if anyone wants to constructively debate the issue please feel free to do so, but my patience is getting thin with those that
simply want to sit back and make offhanded observations and blurr the discussion.
simply stated, if you can add to the debate, please do so, if you just wanna pop in and kick sand, obfuscate, and tell me to do the math without providing
equations, concepts and a drawing or two, then "take a hike"
bob g
I already gave you the answer, many times.
concrete block and float it on a barge in a shallow pool, it only needs to float by a few inches, so even if your barge or pool leake you have a safe failure mode that allows you to fix the leak.
no chain of events to lead to an "accident" either.
-
ok GuyF:
on the one hand you have stated your opposition to resilient mounts because of possible crankshaft/flywheel failures due to
movement of the crankshaft, and now again you talk of the "mother" of all resilient mounts "water"?
somehow i am to believe that if you are behind the use of "water" as an ok mount, that i am out in left field for working through
the enginneering to properly resiliently mount an engine.
do you see how the way your relate things might be confusing?
Guy, respectfully i do pay attention to what you write, i read and reread it many times, trying to sort out the wheat from the chaff.
(chaff does not equal waste)
from the beginning you had issues with the crankshaft being allowed movement, it took me awhile to accept this as many engines do just fine
moving all over the place. but i gave it some thought and figured what the hell, if guy is right then ok, if he is wrong nothing lost in trying to figure
a way to not only isolate from vibration transmission but limit the crankshaft movement (keeping with Guy on this one)
if you have followed the progression of the discussion of late, you will see that we can by design limit the movement of the crankshaft due to rocking.
this is a huge step in resilient mounting an engine if we are to be concerned with crankshaft movement.
the proper choice of mounts provides the 3 axis of movement to be tightly controlled, certainly moreso than a system floating on water, or at least as well as.
???
bob g
-
Mobile Bob,
A few thoughts on your particular engine mounting problem.
You claim that your engine will transmit undesirable vibrations relatively long distances at your place in Kansas. Have you observed/measured this to be the case? The reason I ask is that you cite some rather energetic examples of vibration transmission, trains, rock quarry blasting, etc. I calculated the reciprocating force of a listeroid piston to be 666lbs @650 RPM, based on piston and rod weights given here previously, http://listerengine.com/smf/index.php?topic=1097.105 , reply #118. A substantial load, but probably much less than the examples you cite. It may cause a problem for you, but you don't know for certain until you either a) build it and try it or b) get a geotechnical engineer out to your place and do some soil testing.
I know nothing of the soil conditions at your property, but will assume that your engine will not be placed directly on bedrock, but will have a layer of soil and subsoil separating the engine from the bedrock. I have been researching foundation design for my own application (red clay on bedrock) so I hope to relate a little of what I learned. Soil mechanics is empirical. To characterize soil conditions requires boring holes and taking samples for analysis. The proposed foundation can be analyzed using the test data and the theory of the elastic half-space. Anything less is guesswork.
If you are concerned about vibration transmission from your engine to your home you need to understand how seismic energy is transmitted through the ground. There are Raleigh, shear and compression waves produced by the vibrating engine foundation. All are attenuated by distance from the source. Of the three, the Raleigh waves are the most problematic, they travel near the surface, transmit 67% of the total energy and the amplitude dissipates with distance from the source according to : 1/r.5, where r is the distance from the source. Raleigh waves are similar to surface waves on water. It is possible to erect foundation barriers to the transmission of these waves, but the experts are not always successful with their designs. Additional information is available here:
http://en.wikipedia.org/wiki/Seismic_wave
http://web.ics.purdue.edu/~braile/edumod/waves/WaveDemo.htm
Since most reading this board are of the do-it-yourself mindset they would gravitate away from the engineering analysis and towards guesswork. ;) In the absence of a proper analysis the next best thing to do is assume the soil has poor bearing capacity. In that case a larger foundation footprint than the standard Lister design is desirable. A large foundation adds both mass and bearing area. Both are very beneficial. More foot print distributes the vibration energy over a larger area thereby reducing the force per unit bearing area. The added mass requires that the acceleration of the engine/foundation assembly resulting from the reciprocating mass of the piston is tolerably low.
If you want to hedge your bet further, build an isolated foundation. This is a two part foundation, the engine is attached to the top part in the usual way and this is placed on a lower concrete slab with an engineered pad designed to damp vibrations placed in between. The Unisorb paper I cited in an earlier post discusses this.
http://listerengine.com/smf/index.php?topic=1097.75 post #82
http://www.slideruleera.net/BasicVibrationTheory.pdf
I have changed my opinion with regard to the resilient mount argument. I was neutral, but no more. After examining the pros and cons of each mounting, reading books and papers on foundation design and vibration theory I came to the conclusion that the use of resilient mounts and a welded steel frame of minimal mass to mount the Lister/oid is problematic for all the reasons that have been pointed out in previous threads, if done wrong this design can be dangerous. The worst that can happen with the concrete block foundation assuming it is sized properly is unwanted vibration transmission through the ground and the solution is the isolated foundation mentioned above.
I know this debate has been beat to death and I have no desire to resurrect it. I have stated my opinion and it may or may not be worth what you paid for it. :) Best of luck with your project.
-
see, can't help yourself from moving the goalposts until it sounds like I said something completely different from what I actually said, in order to further your own preferred goals.
I said
1/ mount in on a concrete block so you shift the centre of mass and therefore effort outside the block.
2/ mount this on a small barge in a small pool just big enough to float the barge.
this is not a resilient mount, as discussed here.
a/ the concrete block serves the intended purpose.
b/ any residual vibes are isolated from the enviornment by the pool
c/ the purpose of the concrete block was never, as I have repeatedly stated, to reduce vibes to zero or create human comfort
d/ resilient mounts in place of the concrete block will always prevent the main aim, to shift the centre of mass etc
e/ the methods I suggest have ZERO catastrophic failure modes, you cannot even MAKE them fail catastrophically, this can not be said for any of the alternatives proposed
f/ the methods I suggest have ZERO negative impacts on engine longevity or reliability, irrespective of engine condition or quality, this can not be said etc
g/ the methods I suggest have ZERO requirements for tradesman skills, eg knowing how to make a proper steel frame with radiused fillets and triangulation to take all the loads off the welds or fasteners, this can not be said etc.
h/ the methods I suggest do not require anyone to study and master the admittedly complex and time consuming knowledge required to calculate everything and not end up down blind alleys with guesstimate figures being presented as hard data
i/ the methods I suggest make the most of the SINGLE advantage we all have over commercial economies of scale, eg our ow labour without too much requirement for artisanship in any particular field
j/ I will say it again, cos it is worth saying about ten times, the methods I suggest have ZERO catastrophic failure modes.
k/ you lot are working with listeroids, and the one FACT we do know about them is there is ZERO QUALITY CONTROL
l/ zero quality control = a ticking time bomb, only the short sighted (fools rush in where angels fear to tread) will even contemplate anything other than zero failure mode works to go alongside something with zero quality control, because this is the ONLY POSSIBLE way to make some inroads against zero quality control.
Ask mr belk about birmingham (uk) and london proofing houses, and what you need to do before you can use an unproofed gun safely.
security theater != security
I have always talked security, everyone else talks security theater
-
One last time, for the stupid people among us, namely, me:
d/ resilient mounts in place of the concrete block will always prevent the main aim, to shift the centre of mass etc
Explain the reasoning behind shifting the centre of mass. Provide vector diagrams, links, long-winded paragraphs - if absolutely necessary (please, no tangential topics). My experiences with larger, multi-cylinder engines and searches of the whole internet - which, surely, is the sum total of human knowledge ::) - has provided me with very little insight as to why this is necessary.
It appears to be one of the points on which your whole , rather vocal, argument rests, yet the times I have asked before seem to have been lost in the noise. If you can provide a valid, concise explanation, I will consider a large inertial block in my design. If you cannot, I will simply consider you to be an excellent troll.
-
Smokey:
thank you for your reasoned responce, and links.
for the record i am on bedrock, i have no topsoil to speak of (less than a couple of inches in most places, and those area's on the property that have more topsoil are at a pemium for other uses such as food production)
i do have a question tho
where do you arrive at the 660lbs of down force? would this number not change do to loading? or is this only a balance component of a typical single cylinder lister?
GuyF:
if i moved the goal posts it was unintentional, rather i was only trying to clarify the arguement.
i will state again the following , and perhaps this is the only thing we are going to agree upon.
the use of a concrete mount is the only safe, easy to understand, engineer and impliment system available to mount
these engines. futher it is the only mounting system that has a zero failure rate, save for mounting bolts i would assume.
but as for the mount system itself it is a time proven, effective and safe method of mounting the engine. I concur!!
the design, engineering, and manufacture of a steel subframe is frought with a myriad of very valid concerns, in that
things such as choice of materials, weld quality, brackets, gussets etc are of particular importance, and
they exhibit possible failure modes, that i would also concur with.
now for what i am in difference on
"f/ the methods I suggest have ZERO negative impacts on engine longevity or reliability, irrespective of engine condition or quality, this can not be said etc"
i don't see how you can assert this on just any engine irrespective of condition or quality, except that possibly the concrete block will not exacerbate problems of poor balance and cause failures of one sort or another.
the problem with the statement as i see it is one of masking a serious problem with a 2 ton block of stone. if you have a poorly balanced or horribly out of balance engine, bolted to a huge hunk of stone you can be lulled into a false sense of security in that "the engine appears to run very smooth" when in reality enormous forces are being restrained and in some cases amplified and returned to the engine which "may" end in a catastrophic failure. but i digress
i do have a question or three though
was not your concern with failure initially that of movement of the crankshaft?
and lastly, do you think it impossible to effectively design, engineer and manufacture a steel subframed and resiliently mounted system that would be safe? i am not sure i would accept that premise, but i appreciate your position.
or just unlikely because of each doing what he thinks or feels is right without regard to proper engineering and construction techniques? i can accept this premise, and find no fault with this position.
bob g
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GF:
i also have a question in regard to moving the center of mass
with the cradle mount and attaching a specific amount of weight to the cradle in a specific place under the cradle i can move the machines center of mass to any point i so desire.
while i might do so to center the mass to within a close range of the crank c/l, i see no reason or benefit to moving it anywhere else.
why is the lister engine different in this requirement that every other engine ever built?
what benefits are to be gained by moving it elsewhere?
what makes a lister so special in this concern?
please explain
i have researched many books on the subject, many engineering texts and none of them make reference to moving the center of mass outside the engine as being the sought after goal.
very curious
bob g
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One last time, for the stupid people among us, namely, me:
d/ resilient mounts in place of the concrete block will always prevent the main aim, to shift the centre of mass etc
Explain the reasoning behind shifting the centre of mass. Provide vector diagrams, links, long-winded paragraphs - if absolutely necessary (please, no tangential topics). My experiences with larger, multi-cylinder engines and searches of the whole internet - which, surely, is the sum total of human knowledge ::) - has provided me with very little insight as to why this is necessary.
It appears to be one of the points on which your whole , rather vocal, argument rests, yet the times I have asked before seem to have been lost in the noise. If you can provide a valid, concise explanation, I will consider a large inertial block in my design. If you cannot, I will simply consider you to be an excellent troll.
do as you please
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There's always one that seems to defy all logic:
(http://www.diesel-bike.com/Lister_Gen/Zena_motion_small.jpg)
(http://www.diesel-bike.com/Lister_Gen/Zena_far_small.jpg)
Stopped keeping track of hours long ago, probably blow up at any time, it's running now but I can't hear or feel it.
Maybe already ran through the wall and down the street! ;D
This post is not meant to offend anyone, just to share one person's ongoing project with one of these engines.
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GuyF:
i got in a hurry a while ago, just popped in for a bit and didnt catch an earlier post of yours, i found it and would like to respond.
my reference to you as the "spoiled" rich kid was a figurative statement
i don't know you personally, and perhaps i never will.
you assume i do not want to do the math, and yet you still make no profer of any formula
we can go back and forth forevermore, as we have done for months now.
further it would appear you don't think i want to see all sides to the arguement but rather only pick and choose
what i want to see and make irrelevent all other factors, that is patently false.
you dismiss out of hand what i think or feel (fair enough), but i also dismiss your math and engineering based on your say so alone
and that should also be fair enough.
i use the term "feel/think" based on experience and research, perhaps i should use other terminology/wording.
let me give you another set of parameter's
lets assume for the sake of discussion that the following is true
1. i can weld effectively, with welds that are certifiable
2. that i can research and engineer a subframe system
3. that i can manufacture a steel mount properly, with sufficient weld quality, braceing, trussing, fillets etc
4. let us assume that the design directs the stresses away from welds and bolts, where possible and
where not possible of feasible additional support is added
given the above is it your contention that it cannot work, and will cause problems with longevity and safe operation
of the machine?
again do you think it impossible? or just unlikely to be successful?
as far as understanding forces on welded structural components i am no neophyte, i routinely work with and
rework designs done by engineers in this regard, i am not a bloke with a buzzbox welder and a handfull of farmer rod.
i know you don't care for me questioning your intelligence or integrity or education, or whatever you wanna call it.
i simply persist in asking questions to get answer's, saying something is so does not make it necessarily so.
you speak of concrete and lister engineering,and then there are huge high power density engine built up of welded steel
i know you are aware of them. there are certainly higher stresses inside these crankcases than those that are outside.
for that matter there have been many smaller engines built of welded steel construction as well.
i am doing all i can to understand you and your opposition, if it is one of safety fine. if you are concerned with the
average DIY'er cobbling up a machine of death, then that too i understand.
what i do not understand is or rather do not accept is the premise that it is not possible.
do you see at all where i am coming from?
bob g
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GF:
i also have a question in regard to moving the center of mass
with the cradle mount and attaching a specific amount of weight to the cradle in a specific place under the cradle i can move the machines center of mass to any point i so desire.
aye
while i might do so to center the mass to within a close range of the crank c/l, i see no reason or benefit to moving it anywhere else.
take your washing machine apart, remove the concrete block that shifts the centre of mass outside the drum radius, do a load of washing and come back to me about not seeing any benefit
why is the lister engine different in this requirement that every other engine ever built?
what benefits are to be gained by moving it elsewhere?
what makes a lister so special in this concern?
please explain
i have researched many books on the subject, many engineering texts and none of them make reference to moving the center of mass outside the engine as being the sought after goal.
very curious
bob g
the forces inside the engine at given loads are pretty constant.
but inside an engine these forces work on levers, they are not simple pressure.
pinch bar end -------- fulcrum --------------------------------------------------------------------------------------------------------- handle end
all three places have forces, even though you only feel the hand end, and the bar itself has forces running along it.
moving the centre of mass is similar to moving the fulcrum
cast iron block --- brick fulcrum ---------------------------------------------------------------------------------------------------------------- hands
you have to be careful, either the cast iron or the brick will give
cast iron block ---------------------------------brick fulcrum --------------------------------------------------------------------------- both hands
less chance of breaking the cast iron or brick
more torque and therefore stress on the hands side, but hugely less torque and therefore stress on iron side
it's a bad analogy, same as the washing machine, only solution is do the math
============================================
You say you have looked, and not found this in any engineering texts.
I suggest that if you look, esp if "look" = "google" you won't find anything saying welds are fasteners same as bolts, and good steel structure (eg engine bed) design ensures that all the loads are carried within the structure, and not by the fasteners.
however, if you do a degree course or a proper apprenticeship you will keep tripping over it, same as different hardnesses for plain bearings depending on load etc, and indeed bearing wear, think about it, hard steel journal, that may even be turfrided, a soft lead based shell, and yet the hard journal takes much of the wear in normal service, common sense will tell you youd never have to regrind a steel journal
============================================
shifting the centre of gravity outside the engine pays huge dividends when it comes to s-n curves and fatigue life, which is service life, who cares unless you are using engines designed to never wear to the point of scrapping, eg listers and suchlike.
well maybe those who realise even a 1% lowering of loads internally = 1% less work converted to waste heat, 1% less work converted to hammered lube, 1% less work converted to worn components, 1% less work converted to wasteful vibration that goes to heat the mounts, isolastic or solid, etc etc etc
I have told you all, go and buy a dozen identical cheap 12vdc motors off ebay, vibrator stuff, mount six on springs and six clamped firmly to a brick, use the same eccentric weight on each and a lab power supply and 12 vdc clock in series for each, run em all until they die, tally up the hours, then come back and tell me I am wrong. May cost you ten bucks, nobody wants to do it, much easier to label me a troll.
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ok i give :)
GuyF, i completely understand!!!
holy crap!!
Duh:
i don't want to offend you,, but....
wow,
is that thing anchored to the floor in any way?
please consider anchoring it in a much more substantial way,, please
back to GuyF:
ok ok ok
i would hope you could allow room for somesort of system between that which was posted and the concrete block
i have already said too much
bob g
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Quote:
Duh:
i don't want to offend you,, but....
wow,
is that thing anchored to the floor in any way?
please consider anchoring it in a much more substantial way,, please
---No offense taken. Like I mentioned, many, many hours - no faults noted. Runs daily!
P.S. I had it solid to the concrete initially and the life expectency of the house went down.
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GuyF:
i for one do not think you a "troll" and i doubt that GI really thinks you are either.
what i do think you are (as i would suspect more than a few others do as well) is a cranky, crotchedy, slippery, educated, pain in the ass at times. but of course we probably all are at times as well.
i can explain why the crankpin wears faster than the brg shell, if you like. yes it would seem counterintuitive untill you understand what actually is happening
journals and brgs will not wear if there is pure clean oil, what causes wear is particles of dirt getting stuck in the surface of the babbit material (by design) and thus working as a lap. if the dirt was to stick to the crankpin the inverse would be the result.
well this has been fun, but i have come to the conclusion that i "can" build a successful system to mount the engine. i will do the first one with the 12hp changfa, even if lessons learned are not applicable to a lister/oid (which i am not agreeing to)
there are literally dozen's of successful engine mounts that follow the cradle system, and i see no compelling reason to believe that a lister/oid could not be mounted in the same manner with good result, however...
i have been giving alot of thought to the resilient mount itself, i need a mount that is equal in tension or rather characteristic's in both the up/down plane. it occured to me that the steel clad bushing style that both mack, white, and ford have used successfully for years, and has been used in spring eyes since the beginning of time nearly.
this type of resilient mount has no failure mode at least catastrophically, yes the rubber can fail but the system is caged so escape cannot happen. i will add that to the coppermine sketch for your consideration.
i know you don't like it, but that is the direction i am going to go. i guess time will tell if it is successful at not only isolating the transmission of vibration to the floor and have sufficient safety to alay your concerns.
btw...
can you please repost the dimensions of the one ton block of concrete, i want to run some calculations and do the "math"
respectfully
bob g
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Bob:
Well, I don't really consider Guy_F to be a troll, it just seems he has to be harangued into giving an solid answer sometimes. ;)
Guy_F:
An informative explanation. I shall ponder it over some stiff drinks later.
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GI:
i know,, i too like to jab the gorilla with a stick once in a while.
but so far he dodges quite well :)
comeon GuyF, we still love ya,,, even if we don't have to like ya
or is it the other way around?
:)
bob g
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Bob,
As you know, the piston motion changes direction at the end of each stroke. The number that I quoted earlier is the reaction force seen by the listeroid engine frame each time the piston starts/stops. See volume II of Taylor's book, "Internal Combustion Engine Theory and Practice," page 248, equation (8-8)
This force can not be balanced out in a single cylinder engine. It is sometimes compensated for by altering the balance factor of the rotating parts. When this is done the vertical force component is diminished at the expense of adding a rotating imbalance vector whose line of action points radially outward and rotates on the axis of the crankshaft. When this vector points upward as the piston nears the bottom of its stroke the forces act in opposition and the net force transmitted through the engine frame is diminished. A similar effect occurs at the top of the stroke. When the piston is at mid-stroke the rotating force is acting in the horizontal direction.
This effect is also true for the changfa, but the reciprocating force acts horizontally instead of vertically. The design of the engine mount or foundation must be designed keeping this in mind.
With respect to your situation of mounting a listeroid on bed rock, if the rock was sound, no cracks nearby I would consider attaching the engine to the bedrock directly. Put epoxy anchoring studs into the bedrock, set the engine and generator on a common bedplate and use epoxy grout to level and bond the plate to the bedrock.
If the vibration transmitted to your house is unacceptable, then go the isolated foundation route. Remove the engine and generator from the bed plate, and pour a slab over it all. On top of this, place a vibration absorbing mat and pour a foundation block for the engine. My bet is that this step will not be necessary.
As a side note, I have to say that I have learned a great deal from the discussions that have taken place on this issue. I went back and re-examined my assumptions and prejudices regarding rubber mounts and have gained from it. Please bear in mind that I had already purchased the mounts and built an engine frame. The mounts will not be used and the frame may not be used with my concrete foundation.
To those who are using or plan on using resilient mounts: The engine will move due to the imbalance forces and torques generated. Every component attached to the engine will experience accelerations that are proportional to the square of engine speed. If the engine is attached securely to a large mass the displacements and resulting forces will be small. However if the engine is attached to a light frame, displacements will be large as will the forces involved. If a mount fails or comes loose the engine will beat itself to pieces in short order.
Further, the tapered roller main bearing design of the listeroid has two shortcomings. One, the crank is supported by the tapered roller bearings very near the crank throw, the flywheel is located nearly five inches away in a cantilevered fashion making the crankshaft rather flexible. Two, the bore of the TRBs is somewhat larger than the nominal two inch crankshaft journal diameter. This is a geometrical discontinuity that will raise stresses locally where the step in diameter occurs. It is mitigated somewhat by the presence of a fillet radius at the point of transition in diameter. However if a small or no radius is present, the stress can be magnified by a factor 2.5 or more.
When the engine vibrates and everything goes up and down in phase, fine, but what if you get a situation where the flywheels start getting out of phase with the engine motion by virtue of the flexible crank? You now have a situation where the crank is experiencing bending stresses and those will be magnified due to the presence of a stress riser. If there is no fillet radius present at the stress riser then you could have a situation where the crank is being stressed in the finite life region of the S-N curve. Should the crank break will your flywheels stay with the engine? With resilient mounts this scenario is possible; with the engine rigidly mounted to a massive concrete foundation the probability of this occurring is much less.
In previous occupations I have seen broken automotive crankshafts in stock engines and as a welder, repaired many a fatigue crack in frames of semi-trailers. These things can happen in properly engineered systems. Why take the chance with your listeroid? Why not stack the odds in your favor to the best of your abilities?
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Smokey:
"As you know, the piston motion changes direction at the end of each stroke. The number that I quoted earlier is the reaction force seen by the listeroid engine frame each time the piston starts/stops. See volume II of Taylor's book, "Internal Combustion Engine Theory and Practice," page 248, equation (8-8)"
you are going to have to walk me thru your calculations on that one, i read the section and came to a couple of conclusions,
1. the piston slows as it reaches both top and bottom
2. the author reference to transmission to the frame, is not the mounting frame that the engine sits on, but rather the crankcase
frame=crankcase
perhaps you can explain this part to me, i am all ears
how do you arrive at 660 plus lbs of force being transmitted vertically?
as for the changfa, i did a crude experiment
i picked it up and suspended it on very tall (5") hollow dock bumpers and let her rip
it sits rock still running at full rpm, and with very little movement (almost inperceptiple) at low rpm
and there is no vibration transmitted to the concrete slab floor, none.
so my thinking is the resilient mount will work fine for the changfa.
bob g
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Bob,
Lister calculations: (hopefully no typos, this took a while to write)
Piston assy mass4025g or 8.855lb These values were reported by another poster in an earlier thread
Connecting rod 2742g (big end) or 6.032 lb
1216g (small end) or 2.675 lb
connecting rod length, l, 12 1/8"
crank throw radius, r, 2.75"
After reviewing my calculation sheet,i realized that my citation above was wrong, I did not use the equation from Taylor's book, but rather one from "Mechanical Vibrations" by J. P. Den Hartog equation 5.13 page 177. I shot from the hip in the earlier post, my apology to you sir.
Vertical inertia force
Fz=(mrec + mrot) r w2 cos wt +mrec r2/l w2 cos2wt
mrec = reciprocating mass
mrot=rotating mass
w =angular frequency of the crankshaft, (radians/sec)
t=time
force is maximum when coswt and cos 2wt =1 at 0degrees. top dead center, then
Fz= (mrec + mrot) rw2+mrecr2/l w2
w=650RPM*(1min/60 sec)*2pi radians/1 rev)=68.068 rad/sec
mrec=mpiston assy + mrod,small end=8.855lb+2.675lb+11.530 lb
mrot=mrod, big end=6.032lb
386in/sec2 is the gravitational constant
Fz=(11.530+6.032)lb*(2.75)* (68.068)2/386+ (11.530/386)*(2.75 2/12.125)*(68.0682)
=579.7+86.31
=666 lbs (hmm mark of the beast, whoda thunk it :))
1) Re: the piston slowing down. That is the rate of change of velocity with respect to time, defined as acceleration. When the acceleration acts opposite the direction of motion the piston slows. Maximum acceleration occurs after the piston stops and begins traveling in the opposite direction
2) Taylor seems to use the term "engine frame" in the same context as we have used the term "crankcase."
Re your experiment running the Chanfa running on dock bumpers (isolators). The large inertia force outlined above acts along the cylinder axis, vertical on the listeroid and horizontal on the changfa. I have outlined my reservations concerning the listeroid on resiliant mounts above, based on my understanding of that particular engine design. As I have little knowledge of the internal design and layout of your Changfa I can offer no meaningful comment. My suggestion to you is to remove the flywheel and inspect the crankshaft also look in the crankcase for any design shortcommings similar to what I outlined for the listeroid. Since the chinese use these engines on small trucks and tractors I would suspect that mounting it on resilient mounts may be satisfactory.
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yup the devil is truely in the details :)
now my question,,, this force of 666 lbs is contained within crankcase aka frame
how do we calculate what force is presented out to the mounts, or in the case of a lister/oid down to the mount bolts?
the reason i am wondering is, at 666lbs the engine would be nearly weightless on the up stroke and be nearly twice its weight on the down
stroke if all the force is not contained withing the crankcase/frame of the engine, this presents a working difference of some 1300 lbs pulsing up and down
it would seem that there is something missing here, perhaps not?
any further explanation would be helpful
now i gotta go find the other reference book you are using :)
bob g
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...this presents a working difference of some 1300 lbs pulsing up and down...
My FuKing picks up that much concrete on every stroke!
What happens if both flywheels are out of balance by two pounds each and happen to line up with the vertical component....? Or, are out of balance 180 degrees to each other?
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you end up with a diesel powered pogo stick :)
i do have to ask though, an engine that is that lively, just bolting it down to a couple of tons of concrete
will make it appear smooth,,, but do you think it will last longer?
but then again it lasted what 6500hrs to start with, and didn't explode !!!
ok more observations
1. if we have a badly out of balance engine, then yes we can have some pretty serious forces at work, better use concrete
2. ah forget it,,, use concrete :)
bob g
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Hotater,
I read about your fuking experiences and was curious about one thing. When the concrete slab broke up how big of a piece was attached to the engine and what would you estimate its weight to be?
On the balance weight; it just makes that vertical force bigger if over balanced a little smaller if under balanced. If the weights are 180 degrees out from eachother, I think the engine would want to rock from side to side.
Bob,
The force is composed of a rotating and reciprocating component. They add at top dead center but not a bottom dead center where the the cosine makes the first term negative.
now my question,,, this force of 666 lbs is contained within crankcase aka frame how do we calculate what force is presented out to the mounts, or in the case of a lister/oid down to the mount bolts?
the reason i am wondering is, at 666lbs the engine would be nearly weightless on the up stroke and be nearly twice its weight on the down
stroke if all the force is not contained withing the crankcase/frame of the engine, this presents a working difference of some 1300 lbs pulsing up and down
I believe this force acts on the main bearings via the crank and rod, therefore the same force is seen by the engine mounting bolts via the crankcase. Bear in mind that his is an instantaneous force it exists briefly at that magnatude when the piston accelerates downward from TDC.
Your last statement pretty well sums up why the vibrations from Hotater's Throb I could be felt in the ground for some distance from the engine shed, course it was slapping a hunk of concrete against the ground at about 10 times a second too.
Anecdote: A good friend of mine ran his 6/1 while straped down to a utility trailer of 3500 lb capacity. I stood on the trailer deck with the motor running. When standing on the balls of my feet the felt vibration would best be described as harsh. Standing flat on the soles of my feet on the trailer deck produced blurred vision.
The really scary number is for the instantaneous maximum torque produced by gas pressure acting on the piston crown. I estimate that to be in the neighborhood of 3500 Ft-lbs :o
The book by J. P. Den Hartog is available from Dover books for about $10.
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Hotater,
I read about your fuking experiences and was curious about one thing. When the concrete slab broke up how big of a piece was attached to the engine and what would you estimate its weight to be?
Making some assumptions on thickness based on drilled holes and what I can see, the slab is about 2000 pounds. Six by seven feet and an average of five inches thick.
It was poured on slightly sloping fill dirt which was then covered with gravel and the monolithic, 'L-shaped' slab poured around and on top of the well plug which is said to be between ten and twelve yards of concrete in an inverted cone eight feet across at the big end. The short leg of the L is where MT-I is mounted. That's the downhill leg, too, ill supported by gravel. The break is roughly along the new slab/well plug boundary. The break is in the form of a 'hinge' still supported by re-bar . The engine is mounted nearly dead center the broken off piece
When the soil was dried out under MT-I the floor would bounce by .050" out at the end. By running a trickle of water next to the foundation I could limit the movement to about .010". Even that rattled dishes a hundred feet away, but not ALL the time.
Small, persistant squeeks in certain weather conditions are things designed to drive you off the edge. :o About time I've finally shouldered the wall enough to be sore to cure a noise, one would crop up somewhere else. ;) Vibrating nose hair made uninterrupted sleep unlikely, too.
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Well Jack, I'm wondering if the soil under your MT-1 foundation had voids in it from the start, or was the soil vibrated out by MT-1s now famous hopping action?
In general, the earlier part of this thread was about mount slabs and steel mount chassis, with various isolation ideas added.
I'm wondering about the soil variables and the interface to the engine / foundation unit.
Particularly after the issue of soil (clay) receding from a foundation; the builder related to his engine / foundation rocking in place.
Compacted gravel was earlier (in this thread) refered to as unsuitable due to instability in one plane (I forget), but it occurred to me that a vibrating foundation assembly would soon alter some base materials in such a way that the engine might sink down, rock, lean to one side, or eventually fall over if the foundation was a cube like block with the engine mounted high enough to be comfortable and safe while turning the crank.
I began to look upon the soil as quixitropic, then as soupy mud and eventually I thought of a boat hull shape that would assure stability in unstable soils, with the engine and generator positioned in the center of gravity so the whole might slowly sink, but not tip.
Then receding soils would be compensated for by the slight settling of the (possibly 'V' bottomed) foundation but the machinery would tend to remain upright, level, and tight to the soil? Being a marine engineer, I thought of a boat floating in water and brought it forward to a Listeroid on unfirm soil. Perhaps an inverted 'T' would be wide enough to prevent tipping, and made long enough to control the reciprocating / rotating surges induced above the base line by the engine.
Scott E
Scott E
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Smokey,
Jack and I each measured the weight of the counterweights on the flywheels of our 6/1s by making bubble balancers. Jack suspended his flywheels and added weight across the hub from the counterweight until the flywheels were level. I machined an aluminum insert that allowed my flywheels to balance on the point of a steel spike with a bubble indicator placed across the center of the hub.
Jack measured his weights as 46 and 47 ozs. and I measured mine as 33.5 and 53.2 ozs. Since no English Lister 6/1 flywheels have been measured to our knowledge we don't know what the counterweight mass was intended to be.
Your comments about the tradeoff between balancing reciprocating forces and radial forces echo those David Edgington made in his book after examining Lister's manufacturing records.
Is there a way to determine what the counterweight mass "should" have been, knowing the reciprocating mass and the crankshaft speed? Or is there a starting point that can be calculated for conducting balancing experiments by trial and error?
Quinn
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Q--
I'm sure glad you ask that. I was afraid it'd already been answered in a complicated message and I was to dumb to recognize it!
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Jack:
its ok,,, i will sit on the side lines and listen with you
you want me to bring the beer?
ok you bring the pretzels and folding chairs
:)
ok guys,,, get with it,,, i got my pencil and paper ready!
bob g
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So.. you've recorded your flywheel weights and assembled your engines...Now what?
Do you then assemble the entire steel mountframe and generator etc, start it up and measure the mils of vibration on 3 planes?
Then go to the machinery foundation article posted in the beginning of this thread and follow the soil compation test, and using the mass of your machinery and the mils of vibration, calculate the required foundation?
That seems to be a pretty big problem with a lot of hard to nail down variables...?
Each of these engines is so unique in vibration that the original Lister mounting advise would just seem a starting point.
Scott E
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ok Jack, hold my beer, i can't help myself
on this balance issue
sometime ago, there was a guy on this board that described how to dynamically balance a listeroid.
his engine was somewhat resiliently mounted but i don't remember the particulars
in the truck shop you dynamically balance a wheel/tire, drum the whole rotating assembly in the following way
the wheel is jacked up about 2/3 biased, so that there is 2/3 of the weight on the wheel that is on the floor, and 1/3 on the raised wheel
there is a sensor placed under the axle, magnetically attaches to the axle and this sensor fires a strobe light
you then mark the tire with chalk anywhere
you spin the wheel up to speed, and with the strobe find where the mark is
you then stop the wheel and rotated the wheel by hand to put the mark to the same place the strobe put it
then the weight goes on the bottom, i don't remember how you detemined weight, but if i recall there was also a meter
that gave the relative motion and the weight needed
you placed the weight and spun it up again and retested, 9 times in 10 it was spot on, so...
why couldnt a lister flywheel be balanced by the same method, and using modeling clay as someone else here suggested to tempararily place weight till you got it right, remove the clay and weigh it, and then either remove weight from the opposite side or add the clay weight to the light side
then do the other wheel, you might have to go backand forth between them a few times to get it right but i see no reason
why one could not get an engine damn close to perfect in balance at a set speed
the interesting thing to note is critical speeds, truck wheel assy's clearly illustrate this phenomenon as well
you can balance dynamically at 60mph and be spot on and silky smooth and then watch as the wheel spins down and
witness it going thru critical speeds starting and stopping out of balance at these critical speeds, usually at two speeds.
generally the truck wheels are spun and balanced at the 55 to 60 mph range, and they don't worry about the offending lower speeds, it is a comprimise based on the fact that the truck spends far more time at 60 than at 30 or whatever.
my bet is that one could as the previous reference stated run the engine on a somewhat resilient mount (even if you don't like it) and use a feeler indicator to find and isolate the heavy side and by trial and error add and subtract clay to the light side (down side if the feeler is up top) and get the thing balanced dynamically at the rated speed.
then weigh the clay and make the changes to the wheels,,
then mount the engine back to whatever you choose for a mount
i know this is what i am going to do
ok Jack,,, hand me back my beer
sitting down now,,, :)
bob g
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Scott,
Yes, it is just a starting point. The point of all this is just to get the balance as close to "factory spec." as possible. I think the flywheels made at Dursley were probably pretty uniform. They had to be better than the ones made at Rajkot. Jack's counterweights are within an ounce of each other. Mine were cast 19 ozs different which means there is a lot of force acting on the end of the crankshaft every time it rotates. But at this point, I don't know whether I need to add weight to the light counterweight, or grind it off the heavy one.
Quinn
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Vertical inertia force
Fz=(mrec + mrot) r w2 cos wt +mrec r2/l w2 cos2wt
and
The really scary number is for the instantaneous maximum torque produced by gas pressure acting on the piston crown. I estimate that to be in the neighborhood of 3500 Ft-lbs Shocked
the feeling of satisfaction (not that I am in any way suggesting I deserve any of the credit) from seeing someone go out and do their research, find the equations, do the math and then trust the answers because they worked the whole problem themselves and didn't use any variable or take anything on faith, even though said answers are "shocking", is immense.
smokey has done this, and the inevitable by product of this is he now has a "working model" inside his head of one aspect of these engines, and an inevitable and unavoidable consequence of that working model being there, and being absolutely trusted because it is "all his own work" and none of it is taken on faith or estimated, despite it being "shocking" and therefore contrary to "common sense", is that this working model once created inside his head continues to work, and starts using itself as a known and trusted yardstick to compare to all sorts of other aspects of these engines.
smokey has decided to walk away from the cash and time he has already invested in resilient mounts, from my perspective this is an inevitable consequence of creating that working model in his head..... somewhen about now he will make the leap from peak transient torque under NORMAL FULL RACK operating conditions being in the region of 35 hundred foot pounds, to wondering what it is in a gotcha moment when conditions ain't normal and you get detonation, and a siezing bearing or some other out of bounds load, 35 thousand foot pounds mebbe? and then you calculate the shear forces on a cracked crank or broken 3/4 mounting bolt or sheared keyway and find you're in the ballpark........
I like to use the analogy of electric cars.
If you had an electric car with the same performance, range and endurance of an internal combustion engined car, and you wanted recharging time to equate to refuelling time for the internal combustion engined car, then sooner or later it is going to dawn on you, IF YOU DO THE MATH, that the standard small unleaded nozzle in a car (not truck) fuel pump delivers energy at a rate equivalent to something between 5 and 10 megawatts....
So if you want to charge your electric car with as yet undeveloped battery technology, you need as yet undeveloped room temperature superconductor technology to carry the 10 megawatt load.
My local petrol station has 16 pumps, that's 160 megawatts, there are about ten gas stations in exeter for cars (excluding the truck ones) so that brings us up to 1.6 gigawatts, this is for a city of quarter of a million people only, just for cars, so basically exeter needs;
a/ supercapacitor battery technology that does not yet exist
b/ cheap room temperature superconductor technology that does not yet exist
c/ a fairly large nuclear power station inside the city limits
and this will JUST take care of the fuel cars use, never mind commerical vehicles, trains, domestic and commercial premises, etc etc.
If exeter is to go 100% electric then we need supercapacitor battery technology and room temperature superconductor technology that doesn't exist, and maybe a 10 gigawatt nuke plant inside the city limits. And every other town and city in the country is going to need the same per quarter of a million people.
Wind power? Solar? Wave power? used cooking oil?
Doesn't even begin to make a dent in a dent.
Rubber mounting a stationary engine is a bit like planning to solve peak oil with renewable energy sources.
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ok Jack, hold my beer, i can't help myself
on this balance issue
sometime ago, there was a guy on this board that described how to dynamically balance a listeroid.
his engine was somewhat resiliently mounted but i don't remember the particulars
in the truck shop you dynamically balance a wheel/tire, drum the whole rotating assembly in the following way
Cast iron is not tyre rubber.
tyres at speed deform wildly, hexagonal, octagonal, ANYTHING but round, so centres of mass move around the axis.
this is kinda symptomatic of the "problems" you and I have bob, you can't just pull the bits you like out of truck tyre balancing and apply them to flywheel balancing.
a flywheel is SO FAR AWAY from a truck tyre it is unreal.
flywheels are connected to crankshafts, rods, pistons, etc, which are eccentric masses, reciprocating masses, mixtures of the two, truck tyres aint.
flywheels are flywheels
before you can do anything you need to KNOW FOR A FACT if the flywheel is supposed to simply be in perfect balance, or if it is meant to counter some portion of reciprocating or eccentric mass, and if so, PRECISELY how much of each.
Even "shade tree" dynamic balancing on the running roid is problematical, see smokeys calculations, what bloody rack position are you doing your balancing at, cos believe be it makes a hell of a difference if the sweet point is SUPPOSED to be about mid rack and you move it one way or another and then find yourself at the opposite end of the rack...........
I am MOST POWERFULLY reminded of people I knew who decided to drill their own brake disks for various reasons and alleged benefits, the lucky ones shattered the disk in the press, the unlucky ones had the disk shatter when it was glowing at eek mph and the only one of them still alive is a t5 paraplegic.
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famous last words of an ole southern boy...here, hold my beer and watch this///sid
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Mobile Bob---
You've described the wheel balancing mechanizm I've been trying to find! I remember them from the mid 60s.
I'd like to use one on a 'jumper' with an adjustably rigid mount so that the engine would be 'allowed' to move a little so that by trial and error and in small increments the solution is found for each engine. Once it's smooth, bolt it down solid and forget it.
I was never able to bolt MT-I to ANYTHING that kept it from wiggling just a little...which became more, which soon broke something.
Either MT-II is remarkably smooth....OR the new concrete base is exactly right, because it doesn't even hum!! It rings!
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I'd like to use one on a 'jumper' with an adjustably rigid mount so that the engine would be 'allowed' to move a little so that by trial and error and in small increments the solution is found for each engine. Once it's smooth, bolt it down solid and forget it.
Probably the best solution for those who can do it.
Either MT-II is remarkably smooth....OR the new concrete base is exactly right, because it doesn't even hum!! It rings!
Either that or you've got enough concrete to mask the cataclysmic forces at work ;)
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I was never able to bolt MT-I to ANYTHING that kept it from wiggling just a little...which became more, which soon broke something.
Either MT-II is remarkably smooth....OR the new concrete base is exactly right, because it doesn't even hum!! It rings!
Jack...your MT-1 was probably like my Vidhata. On my first run I had to set the bucket of my loader on the frame to keep it in the same county. I added 1.2# (took many tries to get it) to each flywheel in the counter balanced area to make it sweet.
I'd like to use one on a 'jumper' with an adjustably rigid mount so that the engine would be 'allowed' to move a little so that by trial and error and in small increments the solution is found for each engine. Once it's smooth, bolt it down solid and forget it.
That is how I did mine...only I had it on resilient mounts after I got it close.
Your MT-2 is like my kit engine. Excellent flywheels! The secret is in the % used for the recriprocating mass. I now have two sets of flywheels that turn a beast into a smooth thumper. If I had a bubble balance I'd tell you what the magic number is. I can tell you 65% of recriprocating is a good balance. 63% or 66% may be better but I am tired of experimenting. We have a big ol cast iron piston we have to deal with. I stole this from the a Injun site ( they stole mine!)
(http://listerengine.com/coppermine/albums/userpics/10081/STATIC%20BALANCE.jpg) This is how they do it. I have balanced two engines so far and have learned a lot that I really didn't want to get into. Also if you mount a bad flywheel 180deg off from a good flywheel it could be done staticly, basicaly the same as what the Injuns are doing.
For the life of me and my thick head I can't even grasp why this engine needs concrete http://video.google.com/videoplay?docid=-9194771268947755783 other than I don't want to ever move it or build a frame. If I was off grid and knew I was going to be there a bit I would use concrete for sure. But it would be balanced before it was set.
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Master GuyF:
it is with some restraint i respond to you once again.
bear in mind i gave up the fight yesterday, or did you miss the post?
you have no idea what i know or don't know about tires, i suspect i know a damn sight more about truck tires than you
will likely ever know,, but... that being as it may "of course they change shapes" and "of course that will effect the center of gravity"
the example was never an apples to apples comparison but a reasonably expedient way of explaning the process, the process by the
way is used to dynamically balance turbocharger, turbine wheels etc,,, and they are not made of rubber, but the process is basically the
same, as is the equipment used albeit much more accurate equipment for the latter.
have you ever dynamically balanced anything by rude methods? i doubt it!
as for the formulae, isnt it fascinating that smokey can pop up and answer a direct question with a direct answer?
how long have i asked you for anything like a formula? months? and i get F=ma from you and then be told to do the math?
seriously Guy, do you not see the frustration, you give me hell for being a persistant pain in the ass, but you sir are a dog from the same
kennel. you can't leave it alone any easier than I.
you continually accuse me of pulling bits and piece that i like and rejecting all others, how do you know that? what leads you to even think that?
i don't reject anything that can be supported, documented or proven out. i do reject offhand comments, "it is so because i say it is so" and being told
that it cannot be done, or it cannot be done safely. however...
i do accept the fact that just because something can be done does not necessarily mean it should be done.
moving on.
"before you can do anything you need to KNOW FOR A FACT if the flywheel is supposed to simply be in perfect balance, or if it is meant to counter some portion of reciprocating or eccentric mass, and if so, PRECISELY how much of each."
i am aware of that as i would suppose most anyone that has been around for any length of time, example the 350 chevy vs the 400 chevy, the former is internally balanced adn the flywheel is balanced seperately in its own right, the 400 however is externally balanced with a counterweight on the flywheel or flexplate. both systems work, mix em and you have problems.
now going to a listeroid, no counterweights so they have to be externally balanced, and yes you can weigh all parts and do the math and get close, but then you still may (likely) have dynamic balance issues, these issues are not engine load dependant but rpm dependant. if they are load or rack dependant then how the hell you gonna calculate balance? you cannot, because it is not static but dynamic and non linear.
and oh yes lest i forget,, what did i say that made you think i was going to bore holes in anything? i also venture to state that i know as much about boring holes as anyone, and more than most when it comes to where you "Don't" bore holes. were you thinking i was supporting the boring of holes in the flywheel? seriously? if not where the hell you coming from?
oh and btw, if you think because i threw in the towel on the resilient mounting debate, think again :)
if you have done anything you have only strengthened my resolve.
back to the balance issue, what exactly is your problem with dynamically balanceing the running engine at rated rpm?
even the rude method i laid out would enable a significant improvement to a listeroid that was a holy terror would it not? is that a bad thing?
would it be perfect? probably not? would it adhere to GuyF high standards? certainly not! is it possible? definetely yes!
in closing i have two final questions for you
1. what would you change with a listeroid (if money was no object) to make it able to stand resilient mounts?
2. what was the dimension of the 1 ton block of concrete? (why do you avoid answering this one?)
bob g
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xyzer:
how is that possible, havent you been keeping up?
there is no way you can balance that animal without a phd in math!
you obviously were blessed by the god's to have done the impossible
by simple trial and error.
but alas you must have done some math as well to come up with 65%
and you took an engine that you had to hold down with a tractor, and made it
run smoothly,, amazing
damn good job man!
bob g
ok, i will go back to my chair now :)
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Rubber mounting a stationary engine is a bit like planning to solve peak oil with renewable energy sources.
I agree.
In both cases one must "think outside the box" and find new way around old problems.
It seems like the most logical manner to deal with the variability of listeroid engines is to find a way to "standardize" them retroactivly in terms of balance. I suspect one of the reasons that balance can be a so variable is that it is taken for granted that they will be bolted to massive bases and any destructive or overly annoying harmonics will be sufficiently damped by this mass.
It appears many involved in this discussion are also suggesting balancing the engine/flywheels as a first step in minimizing the operating vibrations of a listeroid. I am sure that there are discussions on this somewhere in this forum....I am just too new to know where they are. So ...regardless of how a Listeroid is mounted...balancing it appears to be a logical first step. Does anyone disagree with this?
I believe that the suggestion of a floating barge mount has merit. Except of course for my needs.
I would have to heat the shallow pond for 5 months each year to keep it liquid. Possibly there are more "modern" materials that can be substituted safely and effectivly for shallow water. The most preferrrable might be shock absorbing matting or foam. Simple. No moving parts, low failure likelihood. Ther may be other simple ...even scavengable options as well. Often a discussion which brings lots of differing POVs together will bring such options to light. I do not consider all of these discussion "bull sessions" since they often do result in some very good results that are then tested and refined.
I would prefer an engine mount that is as light as practical and see no reason that any mandatory weight must be concrete. Sandbags would seem to be much less expensive, adjustable, and "portable" than even a 1/2 ton concrete block. Is there any advantage to using conrete for mass over sand?
I DO believe strongly in safety measures both active and passive when any dangerous activity is undertaken. And I consider developing an engine mount for a highly varaible (quality/balance) engine a dangerous activity. As such I plan to build in safety measures whenever possible. The most basic would seem to be an automatic shut off mechaism that can be tied to lloow oil/high temp/or ecessive engine movement. If such a shut off design exists I would be very appreciative of anyone that can point me to that discussion/design. If it does ot this may be a good discussion to start and link to.
Midnight again ..and a long day tomorrow.
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xyzer:
how is that possible, havent you been keeping up?
there is no way you can balance that animal without a phd in math!
you obviously were blessed by the god's to have done the impossible
by simple trial and error.
but alas you must have done some math as well to come up with 65%
and you took an engine that you had to hold down with a tractor, and made it
run smoothly,, amazing
damn good job man!
bob g
ok, i will go back to my chair now :)
No math! all trial and error!....I watched all the number crunchers and they never mentioned the %. I took it in to have it dynamicly balanced and the first thing the guy asked is what % do you want?...hell i didn't know! So we went for 50%......crap a shaker! That didn't work so I took the flywheels off of my smooth running trial and error Vidhata flywheels. We stuck them on the crank we were trying to balance added weight to the crank bobweight till it balanced then (here is the math part) weighed the bobweight subtracted the roatating weight and figured what % of the recriprocating was left and wala 65%. He explained to me that all engines have a perfect % at set rpm's V8's will use 50-55% up to 5000rpm 6-7000rpm will need 60-65%. the faster it goes the heavier the (aluminum) piston gets. Our pistons are one heavy chunk! and 65% will help tame it. It has to do with the ratio of rotating mass to recriprocating mass. The lighter the reciprocating the lower the %. So if you have an aluminum piston don't use the 65% value......it might be 55%...I'll let somone else figure that out!
Dave
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Dana:
1. i fully support the contention that the listeroid should be balanced as well as is practical no matter what the mount.
there is evidence that an unbalanced or badly balanced engine will have these forces returned from the mount (either concrete or resilient)
to the engine, with the possibility of destructive consequence.
(and i don't wanna hear about little electric motors with offset vibrator wheels, that is apples to oranges)
2. i also find no fault with the floating barge concept, where there is sufficient water of course that is not frozen.
even though i have trouble reconcileing the difference between rubber and water
3. there is no reason the material has to be concrete, it can be anything heavy as GuyF has stated lead, depleated uranium, etc
4. one can certainly build a subframe that is far stronger than either the crankcase or the bolts that mate the two
but this does not obviate the need for safety controls should some random event take place and stop the engine dead from full rpm
something that i have seen not once in 32 years of working with diesel engines, but it might happen.
bob g
ps, if i came off rude it had nothing to do with you Dana
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xyzer:
you are my hero, trial and error, who woulda thunk that?
GuyF:
i am doing all i can to keep from telling you to kiss my @#$
but i won't, well i guess i sorta did,,, oh well :)
there i said it!
here we are you and I, kicking sand and all the while the world goes on spinning
and folks like xyzer just keep on doing, trial and error, and guess what it works.
are you seriously going to tell us that had he just bolted the engine to a ton of crete
would have eliminated his issues with that engine? i would certainly hope not!
if so, how you gonna propose keeping it attached to the crete? gonna weld it down with
malleable concrete rod? does that require hi freq and a tig torch?
ok,,, i quit,,, i will be nice now
nah... i aint done yet, just getting started :)
bob g
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Bob or anyone I guess. Can anyone do the math.... (I'm good in trig but I don't deal with physics #’s that much) tell us all i guess what the perfect % of a 6/1 should be mathematically? You will have to compromise the fore and aft (rotating) with the vertical (reciprocating) to apply force equally in 2 directions.
Small end of Rod 1147 grams= 2.529#
Piston assembly 4024 grams= 8.871#
Big end of Rod 2584 grams= 5.697#
Note observation....the Vidhata will run with no load damn smooth (like I can't believe it) on resilent mounts. When a load is applied it will start to move about .05" total movement pulse and a slight twisting movement. I believe these minor movements are partaly the pulse and also torque applied on the gen side. so maybe it needs 66-68%..? It may then jiggle a little at no load instead.....pick your poison!
Dave
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Dave:
personally i think you are so damn close that doing the math is not going to improve the mix
at a movement of .05" at load is not much movement at all, much of which could be negated by
the design of the subframe and the choice of mounts.
i rather doubt that you would get smaller movement mounted on stone, floating on a barge in a pond.
perhaps bolted to the QE2 in the middle of lake superior, maybe... but as granny used to say
"maybe so but i kinda friggin doubt it"
Dave how far down into oregon are you, i might have to make a road trip :)
bob g
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xyzer:
how is that possible, havent you been keeping up?
there is no way you can balance that animal without a phd in math!
you obviously were blessed by the god's to have done the impossible
by simple trial and error.
but alas you must have done some math as well to come up with 65%
and you took an engine that you had to hold down with a tractor, and made it
run smoothly,, amazing
damn good job man!
bob g
ok, i will go back to my chair now :)
I've been watching this and other posts for sometime now and it's amazing to see "who" or "what" can be potentially "discredited" because it is not backed by some marvelous degree. There is merit in higher education, true, but I can attest to many successes in trial and error. Additionally, every year during my home energy tours, fairs and the likes, I have many folks with various degrees in education asking "me of little degree" questions - some of which are very basic (these are in fact folks with electrical and engineering doctorate degrees).
So, with no disrespect to this board or members, Thanks xyzer for stepping out and sharing your experience regarding the balance issue.
Duh
http://diesel-bike.com
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Just a thought guys I might be wrong. When balacing flywheels the weight take to get if right should be split in half.One half the the wieght goes on the outside of the flywheel and the other half goes on the inside. Kinda like they do with car tires. I think it takes care of lateral runout. Maybe somebody here could add to what I am saying Thank Tugboat
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Crankshaft throw wieght should be as close = to mass it is hooked on to---con rod,piston etc. I dont have 6/1 or any . Wish I did
maybe I could tell more on the balance of things . Could anybody tell me if the throws on the crank are drilled? Thanks Tugboat Tom
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Bob,
I spend a lot of time on a forum at which I get some very rude posts directed at me fairly regularly.
I have seen nothing rude directed at me here so far. Though I DO see some of the same dynamics on this forum as many others due to personality and philosophical differences. It is just a fact of internet forum "life" IMO. We have to live with it as long as it remains civil. Ironically
I see several POVs here that may appear mutually exclusive to some...but seem to me to not be. In fact I believe that the best "answers" will involve them all. I am going to try to explain this but it may appear to ramble a bit. Please bear with me...I probably have much to learn and am hoping the feedback will provide a learning experience.
Listeroids are not Listers.
They are "cheap knockoffs" of the venerable design. The quality appears to vary to a huge degree and though I beleive that it is not possible to expect QC at teh assebly plant to be to high or even uniform standards it appears that some of the current importers and assemblers are attempting to provide secondary controls for quality and uniformity. Still it seems the only true QC is in the hands of the final user. The procedure for inspecting, cleaing, and assembling the engine seems to be fairly well documented. But it appears that the logical "next" step of balancing the engine/flywheels may not be. It may be that the QC for Listers was not up to modern standards either. And I know for certain that the ability to weld was not the same when the Listers were first marketed. I suspect that the safest "one size fits all" advice that the ompany could provide was "bolt your Lister to a big block of concrete". And as with the engien design itself the modren makers of Lister"oids" tend to simply copy rather than innovate despite the options we have that did nto exist even 50 years ago. The safest option may still be "bolt it to a block of concrete" but this appears to be an attempt to innovate.
Attempting to mount an unbalanced engine would seem to be foolish. Especially since some examples seem to exist of well balanced engines working very well with very minimalist mounts. I am a strong proponent of adjustability and adaptability. But I do not feel is has been proposed that a mount can be desinged that wil compensate for a very badly balanced engine. To the contrary..it appears to me that most participating are promoting only running well balanced Lister(oid)s no matter what the mount.
Again..I would really appreciate anyone more familiar with this forum than I am pointing me toward any definitive discussion on balancing Listeroids.
I have found four iwith balance in the topic and will try to find time to read them and summarize the info contained (if someone does not beat me to it) when my work is done today. The link to the search results follows http://listerengine.com/smf/index.php?action=search2..I hope. Still learning the available post options.
So lets assume a well balanced engine/flywheel is possible and is the first step in any mounting exercise.
And for now lets limit discussion to a single cylinder engine. It will make the discussion les confusing..and what we learn as we progress should make adapting the results to a twin cylinder easier.
The mount design would seem to become much simpler if we do so.
The forces we are then attempting to "tame" and "isolate" become a movement of less than .05" in any direction, the "soundwave" generated by the small explosion inside the cylinder every four revolutions, and the energy generated by that explosion being rythmically applied to the spinning mass of the flywheels.
We also need to maek provisions for the damping of larger movements during spinup and shutdown as well as an automatic shutdown "switch" in case a major ...potentially destructive...harmonic resonance occurrs.
I am sure I have missed something.
Can any Devils Advocate reading suggest what that might be?
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I would like to address the "Listeroid mounted on a barge floating in a pond" idea.
Water is a non-compressible fluid. The surface area of the bottom of the barge, not far from the bottom of the pond creates a linkage for the transmission of vibration.
I was at work on a barge in Elliot Bay during the Nisqually earthquake a few years ago. The barge was tied up to Pier 47 in Seattle. the water was about 25 feet deep under the barge.
WHEN THE QUAKE HIT, THE WHOLE BARGE SHOOK AND RATTLED.
Oops, hit the cap lock there by accident, but you get the idea. It was like being on land, the quake energy was transmitted right up thru the flat bottom of the barge, and stuff started falling off shelves etc, I stood in the water tight door opening for some protection. When the tremor was done, the pillings of the pier continued to sway, east to west for a few seconds. The quake was felt thru the water as solid shocks, not rolling waves. It felt more like a collision with a tugboat or something, except it was more vertical.
Anyway, the first post on this thread has links to PDF files on machinery foundations. I actually read it! Soil acts like a dampened spring after the initial compaction. I suppose that means you have to dig down below the frost line so cold weather does not effect the spring rate, then you need to protect it from changes in moisture content, by putting a roof over it, and not building it on a flood plain.
Hotater mentioned changing the vibration transmission charateristics of MT-1 and it's slab, by running a water hose under it, and also it was effected by the weather. I don't think the barge / pond has any merit, and is certainly too much work.
Scott E
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That must be why lots of earthquake proof buildings use some form of flexible mounts....If all the shelves on the barge were resiliently mounted with the proper values would thing have fallen? I don't believe so. They were basically mounted on concrete.
Dave
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xyzer may have come up with the perfect analogy--- Earthquakes and their damage.
Anyone that follows geotectonic events knows the worst destruction is in soil that 'liquifies'. Mexico City 1985 is a good example. So is the Marino district of SF in the 'World Series' quake.
To support the 'water ain't it' point of view, from the same website regards the Mexico City earthquake referenced above--
http://earthquake.usgs.gov/regional/world/events/1985_09_19.php
"It was felt very strongly by people on board the ship "Nedlloyd Kyoto" located at 17 35.4' North, 102 36.9' West."
Earthquakes that affect people on solid rock foundations shatter masonry, those on 'fill' or aluvial ground suffer more lateral motion damage. Those on well compacted, dry, and consolidated soils suffer the least damage.
Those that wonder what you're neighbors will feel if you get a 'jumper' and mount it on springs can just go rent a soil compactor and run it for a couple hours to see what happens.
;D
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Love that soil compactor Hotater I have ran many of those make you dance on the earth. LOL
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Dave,
You wrote that your Vidhata parts weighed:
Small end of Rod 1147 grams= 2.529#
Piston assembly 4024 grams= 8.871#
Big end of Rod 2584 grams= 5.697#
Total of 7.755 kg
Mine weighed:
Small end of Rod 1194 grams
Piston assembly 3840 grams
Big end of Rod 2819 grams
Total of 7.618 kg [edit: 7.853 kg]
For posterity, some definitions:
Small end: Small end with bushing in place on balance pan. Big end supported off the pan, rod level.
Piston assembly: Piston, wrist pin, circlips, rings
Big end: Big end with rod bearing shells, castle nuts and dipper. Small end supported off the pan, rod level.
It would be nice to have an idea of how much is manufacturer to manufacturer vs engine to engine variation.
Dave, let me make sure I understand you. You say that the counterweight should be 65% of the reciprocating weight? So in your case that's 65% of 7755 g or 5041 g or 11 lbs 1 oz divided by 2 flywheels or 88 ozs per flywheel? Jack and I have each measured the counterweights on our flywheels to be about 43 ozs, so you're saying your balance shop figured you had to add about 45 ozs or about 3.75 lbs MORE to each counterweight, right?
The reason I'm asking is that I was taught that the way you balanced a flywheel was to weigh the big end of the rod, make a bobweight of that amount from sheet lead, wrap it around the crank pin, then balance the flywheel so that when it's spun, it stops at at random points, never favoring any one position.
Quinn
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Quinn,
Yes it is nice to see some other numbers. I should have posted my Vidhata #'s also but didn't want to confuse the issue.
Check your addition... I added yours several times and could not get the same numbers. ?!!!?
VIDHATA
Small end of Rod 1216 grams = 2.680#
Piston assembly 4025 grams = 8.873#
Big end of Rod 2742 grams = 6.045#
-----------------------------------------------------------
Total 7983 grams = 17.599#
Bobweight @ 65% 6149 grams = 13.556#
POWER SOLUTIONS Kit
Small end of Rod 1147 grams= 2.529#
Piston assembly 4024 grams= 8.871#
Big end of Rod 2584 grams= 5.697#
-------------------------------------------------------------
Total 7755 grams= 17.096#
Bobweight @ 65% 5945 grams= 13.106#
Quinns
Small end of Rod 1194 grams= 2.632#
Piston assembly 3840 grams= 8.465#
Big end of Rod 2819 grams= 6.214#
--------------------------------------------------------------
Total 7853 grams= 17.312# ?????? I think I added it up 5 times same answer??!!
Bobweight @ 65% 6091 grams= 13.428#
avg assembly wt. 7864 grams= 17.335#
avg bobweight @ 65% 6062 grams= 13.363#
I am betting the differences in the assemblys will only be a small % in the balance factor another words my flywheels would run well on your engine. I do need to put my P/S wheels on the Vidhata to confirm that!
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Thanks Quinn :)
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6149 is 77% of 7983, not 65%, same with the other numbers.
The 65% numbers should be: 5189, not 6149; 5041, not 5945; and 5104, not 6091 g, respectively as I calculate it.
All else looks OK.
Quinn
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For dynamic balance, I'm keenly interested in the results of the person who bought those big truck tyre dynamic balancers. Could be the solution for variable loads perhaps? If you can static balance to the point where the dynamic balancers are able to capture/offset the remaining varying imbalance, it would be a good solution.
Of course, I take it that you need to have a somewhat moveable mount in order for the dynamic mass to shuffle to the right spot, correct?
Following from that, let me entertain a dangerous thought :
Would it then be possible that a resilient mount machine, with dynamic balancers (that ,er , do their job) would end up with less external forces, thus less stress, thus less chance of failing as compared to a rigid mount?
Blasphemy!
Forgive me, Guy_F, for I have sinned.
(ducks and runs for cover)
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6149 is 77% of 7983, not 65%, same with the other numbers.
The 65% numbers should be: 5189, not 6149; 5041, not 5945; and 5104, not 6091 g, respectively as I calculate it.
All else looks OK.
Quinn
Quinn,
The total Bobweight of 65% is the (rod big end)+(65% piston+rod little end). I should have been more clear. I just put the answers. The 65% is only applied to the recriprocating mass.
Dave
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Guy--
My original idea was to make a 'hula hoop' from poly pipe and wrap it inside the flywheel rim with a couple pounds of birdshot inside and let the weight go where it wanted to, but got to thinking about means of attaching it and the extra force on the rim and chickened out.
If thin epoxy were added with the lead shot and the engine allowed to run, then the weight distribution could be measured after hardening.
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Hmmmm
Wonder how it would pattern in a corn field ;D
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Last night I read every post I could find (using the search function) on this forum regarding reducing engine movement through better balancing. ( I think I burned my retinas) Having drawn on the collective wrok of so many others I cannot claim any of the following to be original.
It appeared to me that he most success was obtained by "fine tuning" the flywheels at operating RPM.
This makes sense to me since it is likely that Listeroid engine assemblers probably just balance the flyweels individually and "call it good". While it makes good sense to remove the piston/conrod assembly in a twin and make certain each is the same wight as the other in a single this would seem unneccesary. And for the sake of clarity I am going to ignore twins for the moment.
The method I saw most successfully used in the discussions I read last night also appears to be very simple
1. Securely mount the engine on elastic/flexible engine mounts.
2. Run the engine up to operating RPM
3. Slowly advance a peice of chaulk to the flywheels until a mark is left.
4. Shut down the engine and add some weight to the inside of the flywheel 180° from those marks.
5. Clean off the chaulk marks and repeat the above until the engine runs as smoothly as possible.
It appears to me that the above procedure could be refined a bit.
For example I believe that he flywheels should first be each weighed so when weights are added they are divided in a way that allows both flywheels to be of nearly equal weight when the balancing procedure is complete.
I propose that once the initial "chaulk lines" have determined the light point at which the flywheels need more weight two small holles (1/8") should be drilled and tapped in their inside rims 1" to either side of that point in both flywheels. Adjusting weights can then be cut from 1/8" thick lead sheet and secured to the inside rim of the flywheels using small bolts and washers. This would allow quite a bit of flexibility in how the weightis are distributed during the balancing procedure. Progressivly shorter and less wide strips of lead sheet would be added and multiple holes in each strip would allow them to be placed shightly forward or aft of the original "light point" depending on where successive chalk lines indicate it has shifted to as weight is progressivly added.
I believe a simple 6 axis "jiggle" indicaor can be developed for those who become fanatical about this procideure. This may be as simple as a bit of welding rod temporarily attached to the top and front of the engine.
It seems to make sense to balance the engine under full load if possible. So developing a mount that makes this simple to do would seem to be a logical concept. I am trying to incorporate this into my third proto design. In leeping with the KISS philosophy most lister(oid) fans exhibit I have attempted to reduce moving parts as much aspossible, reduce the specialized equipment and skills required to fabricate it, and use the most commonly available materails I can think of.
I will post a drawing ASAP.
Since posting a picture is SO helpful in discussion such as this would it be helpful if I also posted theprocedure I use to do this so others can post these easily as well?
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if you attach a pencil to the cylider head (horisonal and parallel to the crank) and then while running hold a paper
up with a support you can get a clear indication as to intensity and direction of movement, up/down and fore/aft
a pencil mounted and point up will illustrate the side to side rocking component and the twisting motion
seems crude, but
some years ago nascar (iirc) banned data aquisition equipement from the race car, but they allow for onboard camera's
some of the crafty teams simply madeup crude wire pull indicators off each wheel and everything the wanted to check, and mounted them to
indicator needles (shop built) and then set the camera up to film it in progress.
crude data aquisition, but it worked exceptionally well,
with an indicator arm, a fulcrum and a longer stylus arm one could make a very useful tool to determine movement of any engine.
i know GuyF, you don't like it,, guess what ??? you don't have to like it
bob g
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danalinscott,
That is basically how I finished off my first Vidhata 6/1 balance. But be aware the chalk mark is not correct. You will find there is a lag of about 90 degrees. The next time I will use modeling clay stuck inside the rim. It can be moved and adjusted easily for weight and location then weigh it and fasten a permanent weight. That is what the guy used to dynamicly balance my P/S kit engine. They don't spin it as fast but fast enough! Note: The centrifugal force will keep it there but I still wouldn't stand in danger zone! If you are dealing with ounces I used stick on mag wheel weights on the inside of the rim. They really stick! Both flywheels don't have to have the same total weight. They just need the proper amount of counter weight for that wheel.
Dave
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Dave, thanks for the clarification. I'm with you now.
Quinn
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danalinscott,
That is basically how I finished off my first Vidhata 6/1 balance. But be aware the chalk mark is not correct. You will find there is a lag of about 90 degrees. The next time I will use modeling clay stuck inside the rim. It can be moved and adjusted easily for weight and location then weigh it and fasten a permanent weight. That is what the guy used to dynamicly balance my P/S kit engine. They don't spin it as fast but fast enough! Note: The centrifugal force will keep it there but I still wouldn't stand in danger zone! If you are dealing with ounces I used stick on mag wheel weights on the inside of the rim. They really stick! Both flywheels don't have to have the same total weight. They just need the proper amount of counter weight for that wheel.
Dave
Thanks....
I think the idea of using modelling clay is probably the best option..and stick on wheel weights are probably more available than lead sheet and made to stick. Much better idea all around than lead sheet now that I think of it.
In order to reduce rocking/twistng in a single cylinder I believe that you actually DO want both flywheels to be as close as possible to the same weight. Neccesary no...optimal..probably. It is probably best to add all adjusting wieght to the lightest flywheel initially...until it brings that one up to the same weight as the heavier one. After that all additional weight should be divided equally between the two.
Does that sound logical?
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In order to reduce rocking/twistng in a single cylinder I believe that you actually DO want both flywheels to be as close as possible to the same weight. Neccesary no...optimal..probably. It is probably best to add all adjusting wieght to the lightest flywheel initially...until it brings that one up to the same weight as the heavier one. After that all additional weight should be divided equally between the two.
Does that sound logical?
danalinscott
Short answer....NO.
you can have a perfectly balanced engine and fasten a big balanced pully or starter ring gear flexplate on one side and it will have no ill effect other than it will take a second longer to accelerate up to running speed. If we had 1 perfecty balanced flywheel that weighed 100#'s with no cast in counter balance(no counter balance correction) and one that weighted 200# with the same perfect balance they would both (theorectly) take the same amount of counter weight at the same radius in the same rotation to offset the rotating and recripocating mass of the piston assembly. Yes the heavy one would dampen some balance issues if not exact, and would slow down the acceleration and also smooth some of the pulse. Think it over ....I could be wrong :).
Dave
Rethink...If there was 100#'s difference it would probably cause a twising motion....but 5-10#'s I don't think so. More thought...:) My Vidhata will run at speed with no load like a Honda.....apply a load and it starts a small twist action. That I believe comes from the generator load on one side....I could play around and balance it out then it would shimmy with no load. It would be like having a heavier flywheel but real heavy!
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Proto design #3
(http://i134.photobucket.com/albums/q115/danalinscott/Proto3.jpg?t=1167415660)
Red denotes elasotmeric material/rubber mat/engine mounts.
Orange denotes 8"x8" treated wood beams.
Brown denotes 2"x8" treated wood planks.
Tan denotes sandbags.
Fusia denotes a welded steel tubular frame.
The rest can hopefully be easily understood.
Sandbags are used to provide dead mass to prevent the wood subframe from moveing, to balance the weight of the generator head and to provide a snubber to prevent gross movement of the steel frame due to transient forces induced at other than operating RPM.
The wood beam subframe and elestomeric components between the engine and steel frame, the steel frame and wood subframe, and, between the wood subframe and floor are intended to dampen any transmitted shock from power inpulses and any residual imbalance after flywheel "fine tuning" is completed.
The Generator head is mounted on a sliding plate to allow for easy serpentine belt adjustment or disengagement from the flywheel. Similarly other devices can be mounted on the horizontal "shelves" provided. These might include a starter motor, an ac or air compressor, a 12volt alternator, a water pump, etc.
If needed an adjustable shock might also be mounted on the end of one of these shelves connecting it to the wood subframe.
Comments?
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Dave,
I believe the twisting force when load is applied with a generator head is due to the asymetrical "energy path" provided from piston to generator pully. I have no clue how to neutralize that without providing a jackshaft that provides an equalized "energy path" from BOTH flywheels. This may not be significant enough to worry about as far as vibration control goes..though I am relativly certain that some energy is lost whenver the flywheels are forced to move in any orientation other then the plane they rotate in. It may not be a significnt amount of energy though. And similarly a few ounces difference between flywheels may not be significant enough to worry about either. However it does seem logical that if any wieght is to be added it should be added to the lighter flywheel.
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That twisting motion that introduces gyro forces into the flywheels is what SCARES me about flexible mounts. Cast iron is real strong in compression, not so strong in tension, downright weak in bending.
A solid mount keeps the flywheels moving in one plane only.
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ok this is from a personal viewpoint
i would strongly recommend against placing any resilient material between the engine and the steel frame
you need to be bolted down to the frame securely and resilient mounting at this point will make for an engine that is not secure
and will only become more insecure with time. in my opinion
the cradle mount is a step in the right direction, but i would raise the ears to the crankshaft centerline, may as well
mitigate the rocking component cause by torque and countertorque, in my opinion
the resilient pads should be moved up under the ears of the steel frame, better leverage advantage and the same isolation qualities, in my opinion
there does not seem to be any secure means of holding the thing down, are you contemplating bolts somewhere?
bob g
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There shouldn't be any twisting forces escaping from the engine-generator frame - all the torque/countertorque forces from generator load are contained in it. So as long as that frame is suitably rigid, there should be no issue with gyro forces from the generator load. Gyro forces from rocking introduced by unequal flywheel masses is still there. Which was why I was considering a mount with a (rather strong) hinge at one end, basically restraining the resilient mount to the vertical axis.
With the balance rings - I've a digital video camera with a high speed shutter. I plan to put a loop of clear hose with a bubble of coloured water/honey around the flywheel and film it. If you play it back frame by frame, you should be able to see where the bubble sits on the flywheel - that's where you need to add mass.
The water and plastic hose is light enough for me to be reasonably unconcerned about it flying off should that occur, as opposed to magnets/lead shot/etc.
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That twisting motion that introduces gyro forces into the flywheels is what SCARES me about flexible mounts. Cast iron is real strong in compression, not so strong in tension, downright weak in bending.
A solid mount keeps the flywheels moving in one plane only.
Hmmm I guess I have to agree....Now I will balance it under load to eliminate the jiggle....
Guy...If you take a bicycle wheel and hold it by the axle spin it up then try to change the axis quickly it is hard to do. I believe that is Hotators point.
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For the sake of (hopefully productive) argument.
From the posts describing sucessful use of elastic engine mounts the spacing provided in my diagram should be sufficent. But it would certainly be very easy to provide a wider spacing if it proves neccesary. As I said it would be simple to add true shock abosorbers between the "ears" and he wood subframe if additional dampening is required. These would be at the end of the ears and angled inward toward each other at the bottom.
I agree that it is probably wiser to provide a solid mount from the engine to the steel frame. The risks do not seem to be outweighed by the possible beniift. Much better to shim and bolt down engine to the frame as solid as possible. Though probably not with hardened bolts. Some "give appears to be desirable....but more is not neccesarily better at that particualar point.
Raisng the ears will shift the weight on them to above the crankshaft centerline. Is it not better to have this weight as close to that line as possible? Woudl there be an advantage ot having it above that line?
The wood subrame is set on resiliant pads on all four corners but not bolted to the floor. It is held in place by the mass of the sandbags piled upon it and within its frame. Dead weight is hard to move and should provide some additional damping of its own on the minimumly flexible wooden frame.
Everything has SOME flex to it. Even the massive crankshaft in a lister(oid).
Energy that is being damped is "wasted" energy. All energy has some associated cost..so wasted energy is wasted money. Even if that damping is via the mass of a concrete block it is lost. So even if it is not critical for any other reason it is a wise fuel cost saving measure in any working engine.
Similalry any twisting motion out of the plane fo flywheel rotation is wasted energy. If such a twisting motion is excessive I would share Hotaters safety concern. I believe however that a well banalnced engine should have very little twist...and that most of what twist remains can be easily damped with mass, leverage, and if neccesary shocks so the flywheels do not have to.
Frankly I beleive that any engine which cannot be balanced to run under load with very little resulting twisting or hopping movement is defective and should probably not be run even if secured on a large concrete block. Of course if there is not alternaive the safest (relativly speaking) way to do so IMO is by employing a very large and rigid frameand concrete block support.
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from my experience i would at least use a grade 5 bolt to secure the engine to the frame, and if it was me i would go all the way
to grade 8
properly shimmed and torqued they aren't going to break, ever!
as for getting the mounts to the crankshaft centerline i am a strong proponent (sp, damn i can't spell crap anymore).
my thinking is that anything one can do to stabilize the crankshaft and limit its movement is a step in the right direction
so placing the crank c/l at the pivot of the mounts, accomplishes this goal easily as it relates to engine movement caused by torque and countertorque
action on the engine/frame combination.
if one balances his engine he should alleviate much of the other motions or movements of the engine, but you will always have torque and countertorques
no matter what you do to these engine, the singles being the worst in this reqard.
now the crankshaft center line is not the center of mass or the center of gravity of the engine itself, but with the added weight (mass) of the steel frame if
it is symetric should get the center of mass closer to the crank c/l as well.
i suppose one could arrive at how heavy the subframe should be (approx) if one supported the engine by the crankshaft and laid the engine over on its side and
weighed how heavy the top end of the engine is as it relates to the bottom end as the crankshaft c/l being the goal for the center of mass.
if i had to hazzard a guess the top end weight is probably 150 lbs, so the frame should be around the same, no higher math being used, just basic arithmetic.
i am certain there are folks that could come up with a better and more accurate way of determining this, but in any event it would be a step in the right direction
as far as i am concerned.
bob g
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I liked the idea of a hinge at one end....
My Harley FXR has an engine/ transmission that is isolated from the frame with rubber isolators and parallel arms to keep it in plane. But the back is held like a hinge thru the swing arm shaft.
But I'm still in favor of the massive concrete plynth of calculated size on tested soil.
Scott E
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The hinged design would allow you to tinker a lot fairly easily - there's no need to design or angle springs etc to stop the engine from flapping about in all 6 axes - it's just the vertical axis that you have to deal with, and you can place a few bump stops to keep things under control in that direction.
So with a frame like that you could basically lift the engine end of the frame and plunk springs/airmounts/rubber mounts/tyres/pillows/sandbags/piston damping assemblies underneath - whatever you want to test out. Careful placement of the suspension component under the engine would result in little weight resting on the hinge. Make it reasonably wide - eg. as wide as the flywheels - and with a good bush/bearing mount on either side at the hinge end would resist rocking motion pretty well - as long as whatever the hinge is bolted to is relatively immovable. You can also then run all your cabling/exhaust pipe/etc out at the hinge centre so that the flexing/vibration is minimal.
This is the design I'll probably go with, but mine will be slightly larger, with the hinge attached to a box frame that completely encompasses the engine. As my engine will be pretty much exposed to the elements, this can then be used for shielding/guarding/noise deadening and hanging things like a small fuel tank, engine controls/alarms, an auto foam fire suppression system (it's pretty cheap, really... if you work at a mine ;) ) and the coolant tank from.
This way I can tinker with various resilient mounts fairly easily without having to stuff around too much with the basic engine frame.
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Well; for the record, I'm against it.
But if you do it, perhaps the best place for the hinge would be just beyond the generator. then the generator movement would be nearly zero, and the engine would be out at the end of the leaver. Motion would be limited to 'up and down' only, and you could test away fairly safely.
Scott E
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well i am against it as well, for one reason and one reason only
you either have to be in the resilient camp or the concrete camp
you can't be in both camps,,, it just aint right..
take a stand man,,, be somebody
"man" a half and half solution, what is this board coming to??
:)
bob g
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I don't believe I mentioned concrete anywhere, but just for you bob, I'll sit that outer frame on some rubber stops.
This way we can skip a lot of tedious argument about about the pros and cons and the inevitable safety issues of hybrid mounts.
;)
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just so you are aware ,,, you could be half killed :)
bob g
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Proto design #3
(http://i134.photobucket.com/albums/q115/danalinscott/Proto3.jpg?t=1167415660)
Red denotes elasotmeric material/rubber mat/engine mounts.
Orange denotes 8"x8" treated wood beams.
Brown denotes 2"x8" treated wood planks.
Tan denotes sandbags.
Fusia denotes a welded steel tubular frame.
Comments?
danalinscott,
Ditto on the solid engine to frame mount!
I like your resielent mount setup, and here is why. I have an operational portable resielient mount setup but used 4/side 8 total of I'm sure a lighter deflection mounts then yours equally spaced the full length of the frame(traditional flat straight layout). What I have found is that the engine end is where they need to be focused. When I take it apart to paint the frame and swap in my new modified 6/1 PS I will add 2 more on the engine end of the frame to add more dampening in the engine area only. When running with a load the engine end will have a slight movement and the generator end has none. Follow me? Yours will focus on the area where the action is! And it has good mass dampining with the generator on one end and sandbag at the other. Yours the gen and sandbag will help dampen twist, fore and aft, and rocking. Mine the Gen head only helps dampen fore and aft. Each to his own on this but I have no where near the mass you have for your lower frame, and if the engine is balanced is not needed (IMO). But I agree it will help if balance is not perfect and you reach your deflection limit on the mounts. My lower frame weighs less than 75# and has 2x4 for skids.
Dave
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well folks it would seem time to summarize a bit if i may
we now have two major camps (concrete and resilient), and sub camps of each
in the concrete camp we have quite a base of information on how to do that method correctly. We know what the results are for the most part,
one can either follow one of the lister recommendations for a concrete base or apply the mathematics and arrive at alternative concrete mount designs
from other posted source information.
pro's:
1. simple to understand
2. proven design
3. engineers seem to like it
4. within the capabilities of any DIY'er
5. because of shear mass, safety is at a high level,
6. indefinite lifespan
7. good isolation, generally
con's
1. permanent mount, so you gotta know where you want it, generally.
2. quality of j bolts my be suspect, so high quaility hardware should be used
3. possible masking of badly or poorly balanced engines
4. soil conditions, or of unknown quality, or such quality that is not static, such as wet/dry cycles, water tables, and other factors
in the resilient camp we have a limited amount of information, what math exists is based on a certain level of subjectivity and interpretation.
we don't have a body of empirical evidence to work from when it comes to single cylinder diesels of this type.
pro's
1. subframe manufacture within the capability of most (but not all) DIY'ers
2. higher level of isolation of vibration and noise to surrounding structures
3. more mobile, if the machine has to be moved it can be fairly easily
4.
con's
1. engineers are hesitant to embrace the concept (generally)
2. subframe outside the capability of some DIY'ers
3. safety is a concern because of many mechanical connections within the subframe
4. engineering and design much more complex
5, the mixed nature or qualities of the engine's make for each design to be matched to a specific engine and application
6. subframe has a finite lifespan, poor designs and poor manufactureing techniques will result in shorter life cycle vs. better design, better manufacture and materials
will result in longer lifespan (and more cost generally)
7. ease of application of different mounting materials can be subjective and problematic,
8 etc.
goals:
the goal is to have the following
1. a safe and secure mount for the engine and related components (the primary goal for every installation)
2. a good degree of isolation of vibration to surrounding structures (the degree of which is subjective and up to the individual )
3. limit the movement of the crankshaft and related rotating assembly so as to lessen gyro stresses being returned to these components
4. a mounting method that is within the reach of the average DIY'er
conclusion:
it is my opinion that one should start with an engine that is a finely balanced as he can achieve, by whatever methods that get the job done. then
1. the use of a concrete block would appear to be the safest, longest lived, simplest, and achievable means to mount the engine and is within the means of the
average DIY'er.
2. the use of resilient mounting designs are going to require engineering that to date has not been done, so it would seem prudent (if one was to go this route) to use
proven mounting systems and components that are used for other engines. The use of stiff and low movement resilient elements would seem to also be prudent.
welding a fabrication skills will have to be at least average, to above average, the use of quality materials is paramount, as is snubbers, limit stops etc.
3. the use of advanced technology such as air bags, shock absorbers, and other technologies should be rejected, because they place many more variables to an already complex problem. the use of these higher degree of movement components allow the engine too much movement and therefore impart significantly higher destructive gyro forces onto the crankshaft and rotating components.
it is therefore my opinion that #1 above is the only way to safely mount the engine, without doing alot of work, and as a means of limiting risk.
the use of #2 above will require a significant amount of work, math, engineering to get it right and have a good measure of safety, but should be within the means of those that are willing to do the work, and ask for (and accept) help where needed.
the use of #3 by anyone less than a degree'd engineer is probably being irresponcible, a path the average DIY'er should not even entertain. The shear numbers of variables envolved coupled with the variable nature of the engine metallurgy, machining, assembly etc. make for such a complex problem that there is likely no way that the average DIY'er will be successful unless he is very lucky.
bob g
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VERY well done!!
>applause<
...and for the record, I agree.
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the use of #3 by anyone less than a degree'd engineer is probably being irresponcible, a path the average DIY'er should not even entertain. The shear numbers of variables envolved coupled with the variable nature of the engine metallurgy, machining, assembly etc. make for such a complex problem that there is likely no way that the average DIY'er will be successful unless he is very lucky.
In this instance I would definitely recommend the assistance of people who sell the suspension components. As I've mentioned before, while the listeroid world is firmly stuck in the non-resilient camp, the maths and engineering for resilient mounting has already been done for many , many similarly large pieces of reciprocating and rotating equipment. It's not a trivial exercise for the person who has never done it before, but for the supplier of such items , well, they do this every day. And they do it for equipment much more expensive than your $1000 listeroid, where the stakes are much, much higher (downtime or equipment damage can run into millions of dollars) . No engineer worth his salt these days mounts a compressor, motor, centrifuge, or pump directly on concrete.
I've done the math roughly. It was basically to check what the suppliers of airmount systems told me, because I like to suss things out for myself. In the 5 minutes on the phone with an airmount supplier, he queried the mass of the system, it's RPM, consulted a few charts and gave me the answer that took me about 2 weeks of research to agree with. In passing, he mentioned all the things we've gone over here - constraining the movement to one plane as much as possible, good balance, checking for rocking action, snubbers just outside the normal range of motion, etc.
And one more thing - the math suggests a very poor amount of isolation with mostly rigid rubber mounts. It also hints of the chance that you'll be unlucky enough to find your mount resonates at some RPM you don't want (eg. 650RPM, or in an overrev situation). All suppliers of engine mounts should be able to tell you what that RPM will be, or provide you with enough information that you can work this resonant RPM out yourself in 5 minutes with a pocket calculator.
Make sure you do it, for your own safety mainly, but also so we don't get guy_f back in here crowing about how he told us it would all go horribly wrong. I don't think I could handle that. ;)
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Tater:
congrats on passing the 1000 post mark, i saw you were close this morning, but missed the magic 1000, oh well better late than never
i guess :)
bob g
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I think that this is not really an extremely complex project from the engieering POV.
Compared to the KNOWN concrete block mounting method it is "relatively UNKNOWN".
Many err on the side of caution..and rightly so. The unknown is ALWAYS more risky than the known.
BUT (and it is a big BUT) those that have balanced their engine and then mounted it on elastic mounts appear to be pretty happy with the results. And form the looks of it these mounts have been relativly crude (no offense intended). I do not advocate elastic mounts for the average listeroid owner at this point. But it is certainly worth pursuing. And I have the feling that once a few hunderd hours are run on a well engineered design it will not be considered nearly as WILD and idea as it seems to be currently.
Taking the suggestions of others into account I have further modified the design I am working on;
(http://i134.photobucket.com/albums/q115/danalinscott/Proto5jpg.jpg)
The square timber subframe is bolted to the 3/4" plywood upon which the unit and sandbag mass sits on.
I doubt that this much mass would be required..but it would certainly be cheap and easy to add as much as needed.
Comments? Questions?
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The sandbags would probably help to contain an errant flywheel(or it's parts) ;D
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Dana:
i am likeing each generation of your mount design, it is becoming far and more refined, and that is a good thing.
problems with the design as i see them (not that all will be problems for you specifically)
1. the multiple components of the steel frame will require quality welds, proper gusseting and fillet form, along with the obvious
things like selection and sizing of the steel itself. this is problematic because many DIY'ers use what they have or what they can
get cheap.
perhaps side rails of your support structure could be mandrel bent and negate the need for welds , just a thought.
2. i like the general placement of the snubber pads, they will limit the motion, but each degree of motion has its own specific needs when
it comes to spec'ing the composition of the snubbers. so i would probably err on the side of very stiff for these units.
3. the outer support elements should be a bit easier to determine the needed qualities for, but i would suggest the need for some form of
up movement snubber or containment.
4. if you move the support end of the steel frame up to the centerline of the crankshaft, you would effectively control the torque and countertorque action
and therefore limit its action on movement of the crankshaft due to these forces. these rocking forces are load dependant (vary with loading) and it would seem prudent to control them by design, and not try and control them with selection of rubber
just a few thoughts, your experience and capabilities as well as the specific's of your engine will likely vary the results.
one thing about it, as ronmar stated you have effective containment, and likely some isolation of noise with the use of the sand bags
that is probably a good thing :)
bob g
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Thanks for the input Bob,
The sand bags are a cheap containment unit for a disintigrating flywheel. They are cheap to make and easy to make, move, and stack. But really I think the probabilty of that ocurring is very low. Still for those who want to be safer....it is not a bad option for even those with cement block mounts.
Snubbers are very cheap. I DO plan on starting with the ones reccomended for each position by the mounts engineering dept and swapping in the next softer and harder mounts in each position to see if an improvementis noted. This is the "developmet" part of R&D.
I already have proto design with snubbers for upward morevement in development. The are easy to add but hard to show in a simple diagram.
I believe that if I raise the (generator and counterwiehgt) support arms hgher the weight will be above the crankshaft and the engineers I have spoken seem to think it is more desireable to have the weight even with or slightly below that point. Remeber tha this is just a rough diagram. The actual height will be caculated to include the generator head (and counterbalance) weight as well as that of the frame itself.
I always consider good welds a given. Sloppy welds are nobodys friend.
If someone is not a very experienced welder one should hire someone who is.
But there will always be those who decide otherwise.
I suspect that eventually someone will skip the "balance the engine" step.
I do not feel I have the obligation to attempt to reverse Darwinism.
If one follows "almost all" of any directions ....they are really on thier own.
Finally....I have skipped the engine shutdown sensors and fuel cutoff mechanism I feel is required for any unattended diesel genset. These are best shown as details once a basic design configuration has been established IMO.
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Other than the big black safety chains from the purple parts to the white part below the wood are missing, I don't see any problem either. ;) ;D
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Other than the big black safety chains from the purple parts to the white part below the wood are missing, I don't see any problem either. ;) ;D
What would that accomplish?
Disregard this post if that was a joke.
I get used to technical duscussions where everyone is focused on the goal..and so sometimes I am simply not ready for those who toss in comments intended only as jokes. It is hard to make the shift sometimes. ;D
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Dana:
one consideration for the snubbers, are the stud mounted bumpers.
one could use the stud and nuts to adjust the amount of compression on the rubber and therefore stiffen the mount and reduce
the movement in that direction, allowing tuneing in that plain.
just a thought.
i would agree that one should start with the basic's
1. engine balance
2. basic frame
3. mounts.
4. etc.
5 etc.
6 etc.
7
8
9
10, engine controls, emergency shutdown etc, being probably the last thing to consider.
"I believe that if I raise the (generator and counterwiehgt) support arms hgher the weight will be above the crankshaft and the engineers I have spoken seem to think it is more desireable to have the weight even with or slightly below that point. Remeber tha this is just a rough diagram. The actual height will be caculated to include the generator head (and counterbalance) weight as well as that of the frame itself."
i think you should be able to raise the centerline of the mount without raising the generator mount or the counterbalance sand bags, therefore keeping the weight below the mount centerline and also accomplish getting the mount c/l on the same plane as the crank c/l, you just have to either lengthen the frame or widen it.
good luck
bob g
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It would restrain the major parts in case everything else goes wrong.
In the firearms industry, and I'm sure a lot of others, it's 'worst case scenario' desiging.
If you drop a hammer just right and try to accidently STOP a spinning flywheel, whatever it's attached to is going to try to leave the country.
A stationary engine is NOT like a stationary car sitting and idling!!
No kidding...I've had run-a-ways with more weight than you represent....that doesn't work when when the occilations keep part of the weight suspended.
Think of manning a sandbag position on a moving vehicle...most of your time is spent rebuilding the wall!
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i think you should be able to raise the centerline of the mount without raising the generator mount or the counterbalance sand bags, therefore keeping the weight below the mount centerline and also accomplish getting the mount c/l on the same plane as the crank c/l, you just have to either lengthen the frame or widen it.
OK Bob..I think I understand what you are saying here.
Is this what you are talking about.
(quick and dirty omitting lots)
(http://i134.photobucket.com/albums/q115/danalinscott/Proto6jpg.jpg?t=1167719982)
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Dana:
in concept yes, that is what i was trying to get across
bob g
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I'm a little uneasy with the use of sand bags as dampening ballast. Durability concerns aside, it seems as though any mass intended to dampen vibration should be rigidly attached to the frame so as not to allow any movement between the two. With sand bags you are, in effect to a small degree, resiliantly mounting your ballast which seems counterproductive to me. Perhaps adding a bit of portland and water to the sand would make it less fluid ;). Just my 2 cents , forgive me if I misunderstood your strategy.
Bill
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I got around ballasts with resilient mounts by slowing the hog down to 325-350 rpms. It's incredibly smooth.
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Dana:
in concept yes, that is what i was trying to get across
bob g
Ok the...make believe the following like a visit to the optician.
Better..or worse?
(Genhead and counter balance omitted...and a bit of other stuff)
(http://i134.photobucket.com/albums/q115/danalinscott/Proto7jpg.jpg)
Biobill..
I don't believe that durability is a major concern. The bags can be constructed of very durable material..and in fact can have some very handy features sewn in (such as "through holes). I am ignoring these for the moment in the quick and dirty drawings. I am for the moment eliminating the gen head and counter balance (is that what you mean by ballast?) to concetrate on the frame for the moment. Iam not ignoring these ..just temporarily eliminating them from the drawings.
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Dana:
personally i am likeing the geometry, but that is me, and i am sure there will be alot of folks that might differ on that.
the sandbags will probably have to be replaced by some form of rigid towers to support the mounts, and anchor the assy as a whole
at least i would think.
in concept it seems better though, to me.
it would appear that the crankshaft c/l is in the same plane as the engine mounts, so the rocking motion should be centered at the crank or rather have
the crankshaft as its pivot point. that would tend to stabilize the crank from movement do to the rocking from torque and countertorque action.
now the question is how to impliment the design, and select the mounts
good luck with that :)
bob g
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now the question is how to impliment the design, and select the mounts
I think that would be jumping the gun Bob.
There is a LOT of work to be done to address some of the other concerns that have been rasied previously.
And I have a few of my own that need to be resolved.
The use of sanbags as towers is not one of them.
Sand filled bags can be made very stable and dinemsionaly easily.
Please don't think of them as the kind used to build dikes in floods.
I mainly chose to use them since they are cheap and easy to fabricate and can easilyhave lots of handly features sewn in, allow a large and adjustable amount of wieght to be used yet easily moved if needed...and that they are a true dead weight and so should not transmitt energy/vibration/sound waves as more solid materials do.
I am working on eliminating most of the welds to address a concern previously stated in this discussion.
Concurently I am trying to lower the estimated cost. (I am Scottish...I can't help it)
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Biobill..
I don't believe that durability is a major concern. The bags can be constructed of very durable material..and in fact can have some very handy features sewn in (such as "through holes). I am ignoring these for the moment in the quick and dirty drawings. I am for the moment eliminating the gen head and counter balance (is that what you mean by ballast?) to concetrate on the frame for the moment. Iam not ignoring these ..just temporarily eliminating them from the drawings.
Dana,
I'll have to take your word on the sand bags durability
What I was referring to was earlier drawings which showed bags as part or the 'sprung' weight. Assuming that they were there to dampen vibration, I felt that something more 'as one' with the frame would do a better job. Your latest sketch doesn't show them so nevermind.
Bill
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Bill the sprung wieght sandbags are mostly as counterwieght to the generator head.
An asymetrical balance is only desirable if it is adjustable when reducing harmonics.
A secndary purpose was to allow infinate adjustability of the preload on the elastic mounts.
I removed them all for clarity. I believe that their slight ability to absorb shock is a desireable trait.
And again..this is nearly infinately adjustable with a few simple tricks.
Why do you feel that a more solid weight woudl be more desirable?
I would not be posting if I thought I could easily "thinkof it all". I value your opion and alternative POV.
I do not want anyone to misinterpret my posts as dismissive.
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Dana:
in some ways i like the use of adjustable counterweighting
this would allow evening of loading on all mounts, and a way of adjusting to fine tune
the rocking from torque and countertorque.
my thinking is the countertorqe action is much stronger than the torque action (countertorque results as the opposing force on the power stroke, and the torque action
results as the opposing force of compression stroke) but here again one would have to tune to the predominate loading of the engine to perfect it.
but i like it! (at least in theory or concept)
bob g
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Dana,
Why do you feel that a more solid weight woudl be more desirable?
Because a solid weight, securely attached, becomes an intregal part of the frame and forces applied to the frame are resisted by the whole mass, all the time.
IMO a sandbag, sitting on the frame will have a boundry layer which will allow a small amount of movement of the frame in relationship to the sandbag. If you think about it as movement from A to B and then back, The sandbag will lag behind the frame when accellerating A to B and will continue in that direction momentarily when the frame reverses direction. The effect will be slight to be sure, but, if the intent is to dampen motion with mass, I think it would be significant. I now understand that this is not your intent, that you are simply trying to even out the static loads on your mounts. I'm a little thick today, got the flu and have been self medicating with hot toddies. :P
Bill
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How "heavy" is your truck on a downhill section of badly washboarded road?
I have 25 ammo cans holding 100 one pound lead ingots each. (it'd sure be fun to check one as baggage.) During my first rounds of Listeroid testing nearly two years ago I used a bunch of those cans trying to civilize an especially energetic machine.
I only tried it ONCE without safety chains. On shutdown a harmonic vibration, that came on in less than a second, shed a thousand pounds of weight and would have been a VERY serious wreck had the engine not gotten through the 'bad' part fairly quickly and calmed back down.
When the shaking starts the weights are no longer valid unless attached.
Think worst case scenario..these ARE Indian engines.
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Tater....
Have you missed the repeated posts regarding the need to balance the engine?
I read you trials with a very badly balanced engine. I do not understand why you fired it up a second time when it was so obviously defective?
But you have a point. Perhaps we should list out (in a separate discussion) the process for starting a listeroid the very first time and include a remote emergency shutoff option.
Hasn't anyone done ths yet?
As far as if a dangerous imbalance develops in a previously smooth engine.
As I stated earlier I plan to discuss automatic safety shutdown mechanisms after the basic design is established.
If counterbalance and elastic mounts don't tame transient harmonics the option of adding a true shock absorber or three exists. And it is easy to add a ton of sandbags to the base if needed. The dead slightly absorbtive weight of sandbags is much harder to "toss" than a solid wieght such as lead.
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Dana:
i think what tater is in reference to is "critical" speed, or at least what i call "critical"speed, as defined as the speed at which balance issues
compound at a certain harmonic and cause alot more movement than usual. even a finely balanced engine will go thru this "critical" speed on spin
up and spin down.
perhaps an engineer can put this in better terms, i know what it is and can give examples of such.
i gave an example of this phenomenon that i have some experience with, or rather have seen first hand aside from lister/oids
that being the dynamic balance procedure of a truck tire,
when they balance one mounted on the truck the dynamically balance the rotating assembly at ~60mph, and all is smooth as silk
until the tire starts to spin down to around 40 and then again at about 20mph the rotating assembly will start to shake again, sometimes violently
at 40 and less so at 20
from what i have seen with the listeroids, they run down to about 350rpm (a guess) or so, and go thru this critical speed at which point they shake sometimes
quite violently albeit for a very short time.
prudent design would account for this phenomenon, and as Jack stated some provision for retension is needed.
it is possible without stops, chains or whatever to limit the travel the frame may well pitch off a sandbag or two.
bob g
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danalinscott---
Theres' something about a *theoretical* point of view that seems to imagine how things 'have' to be. When you're standing, ready, after six months of hard work and start YOUR engine. It's a lot like meeting your first Martian woman...is she pretty or ugly?? ??? Without having been around them a while it's really hard to say. ;)
The book says bolt it to concrete and even tells what mix to use. They supply foot long tie down bolts and give instructions on how they should be used. The pictures of historical stationary engine mounts are concrete blocks with the engine bolted to them. Same with steam engines, big compressors, sawmill equipment, forges, and nearly the entire machinery world until after the 1950s....that's when aluminum engine parts and counterbalanced crankshafts and harmonic balancers and synthetic polymers came into being.
(Stuff the Lister doesn't have)
You can mount your engine on wet sphagetti-Os for all I care....but maybe you should at least LOOK at the typical Indian cast flywheel and crankshafts before you possibly throw pieces of them WAY over the fence.
I used an analogy in Court (just!) once about 'Murphy'. I said, "If there's a storm drain within coin rolling distance of a parking meter, the storm drain WILL catch coins. It's not that people THROW away money (drop, misshandle firearms), it's that gravity and enevitibility have a commonality. If it *can* happen, it *will*, given enough chances."
For your cushions-- Why not use spherical motion mounts limited by a through bolt, like an engine mount. What I see, and possibly missunderstand about your graphics and descriptions, is a cage with flexible 'donuts' to limit motion within the cage.
Bye the way, this is a heavy, single cylinder, vertical diesel without a countershaft. It won't BE balanced, no matter what you do. There WILL be transit vibrations. IS that when the honeycomb section of flywheel flexes just wrong and uses the excuse of gyroscopic torsion to break out and try to change townships?? What happens to whats left behind?
'Worst case' includes defects you can't detect.
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At some particular speed, your engine and the mount it is on will move in sympathy with an external force, of any size. The longer you stay at that speed, the worse it gets, regardless of the amount of force being put in.
There are two ways to get around this :
1. Move that resonant speed up to where you'll never reach it, by stiffening the mount. After a while, you go from rubber to wood to concrete - each step in stiffening increases the resonant speed. Unfortunately, the stiffer the mount, the more force is passed through it to your surroundings. Some people don't want that. As the mounts get stiffer, it gets to the point pretty quick where you might as well just bolt the thing down solid. If you have extra weight onboard, you can take that off as well to raise the resonant speed.
2. Lower the resonant speed to the point that - while you still pass through it on startup/shutdown - the initial imbalance forces are quite small and the engine is only ever briefly there. This requires either more mass, or softer mounts. Really, really soft mounts. For any average listeroid combination, it requires mounts that are so soft that rubber has a hard time filling that role, and air or extremely soft springs are needed.
My biggest concern is for people (bob, I'm looking at you ;) ) who want to use "firm" rubber mounts. It's quite possible to find a resonant point that is at 500 or 800 RPM with this mount and the typical lister weight. The 500RPM is bad, the 800RPM one is worse, as you'll never really see that until something is wrong....
For testing, I would do the following:
Spin the engine up with the decompression on. Get it as fast as you can. Use a small motor, your big muscly arms, whatever. For a resilient mount, I would ideally like to see some jiggle as low in the RPM range as possible. If I can't find it by spinning the engine over and the mounts *are* resilient... I'd be concerned as it implies the resonant point is somewhere further up in the RPM range, where all that force and energy starts to get dangerous.
So say if I spin it over as fast as I can and find it jiggles at 120RPM from engine imbalance, that means it will also jiggle at 240RPM from power pulses. That should be fine - you pass beyond 240RPM pretty quickly when spinning up (one or two power strokes at full rack?), and when spinning down on decomp, there is no power pulse.
If I spin it up with a motor and find it jiggles at 300RPM.... that's bad, as it means the power pulses will jiggle it when it's running at 600RPM. Something would have to be done before I'd start that up.
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GI:
"My biggest concern is for people (bob, I'm looking at you ) who want to use "firm" rubber mounts. It's quite possible to find a resonant point that is at 500 or 800 RPM with this mount and the typical lister weight. The 500RPM is bad, the 800RPM one is worse, as you'll never really see that until something is wrong...."
well first of all i am glad you caught me with most of my clothes still on :)
ok now for your comment
1. i am working with a changfa and resilient mounts for now, as for a listeroid, i will likely go back to concrete (did i say that??)
shhhhhh dont tell GuyF!! :)
2. the changfa goes through the same critical speeds as does the listeroid, just at different rpms
3. the lister normally runs at least twice the speed of the listeroid, so the frequencies are different, as well it is a horizonal instead of a vertical
4. the subframe, as well as the genhead, and 2 alternators, and a a/c compressor all play a part in the "sprung" weight , and
5. the type of resilient mount i plan on using are much different in operating characteristics than common mounts, air mounts, springs etc.
Basically this is an apples to brick comparison, and i am still wadeing thru the computations etc to arrive at a good design for this application
and am working with someone i find to be knowlegable to help with the engineering.
the engine i am working with (r195) is a counterbalanced machine as well so this negates some of the forces at play or reduces them.
the frame itself will be sufficient to contain many times the forces of the engine.
btw,,, do i have a pimple on my back?? hehehe :)
there are so many variables, coupled with the variable nature of indian engines, and variable construction methods, design and other unknown's
i frankly don't see any correct answer that is going to work for all folks for every application.
if everyone was working with crate 350 chevies, st heads from the same manufacture, a specific set of plans, then maybe you could get a predictable
result.
hell even the use of concrete has a few issues related to sizing, soil conditions, etc.
but this continues to be fascinating
bob g
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Tater,
No need for the superior attitude.
I have run several listeroids....and am aware of the "critical speed" (what I refer to as transient harmonics) penomenon.
This can be dealt with in several ways without employing a solid bock of concrete. I am porposing the simplest be tried first and the most certain but less simple be employed if those options do not prove sufficient.
Yes..I KNOW Listers were bolted to blocks of concrete. This was "state of the art" when they were designed. And listeroids copy Listers as much as possible and are employed to a great extent in parts of the orld where concrete blocks are still "state of the art".
But there have been a lot of developments since Listers were first made. I believe that by employing a few of these "new developments" some useful options will be available that are not currently. I do not imagine that anyone envisionsed using serpentine belts to transmit power 50 years ago. Yet it is a "state of the art" way to do so with listeroids currently. I wonder if those who deveoled that concept had foilks who said "I don't know..sounds pretty dangerous" over and over when they proposed that concept. Probably.
Lets see if we can progress on toward more state of the art mounting options without the "it won't work" posts every page of every alternative mounting discussion.
It is noted..in fact very well noted that this it is your opinion that the tried and true concrete block method is the only way to go. And that any other newfangled mounting option is dangerous.
I am just trying to move forward steadily on this part of the project since it is such an ambitious and possibly very involved project of which the mount is only a small part. Thanks for your help..but after a few repetions it isn't really all that helpful anymore.
I don't mean to sound ungrateful or snippish....but you have made your point..no sense in beating it to death.
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With all of us all going in different directions with frames and various resilient mounts - some of them pretty interesting - it means that we can get some good data across a lot of varying setups and thus prove or disprove the general principle of resilient mounting once and for all. That is, if one person has trouble with his particular setup but six other people with differing designs are having no problems, we can generally pin it down to his particular design, not resilient mounts in general. A couple of different designs that work well with listeroids could be used as the templates for others to use.
Perhaps once everyone's got their own particular frame configuration sorted, we could do a generic set of steps for working with resilient mounts? How to use manufacturers data or how to do it by the seat of your pants, how to tell if/when you're going to get into trouble, things to look out for, safety considerations, how to tweak things, etc. Would probably save the next poor sod from having to read through about 500 pages of heated debate on various different threads.
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ok i can't help myself, this has been a pet project of mine for some months now, that is the ongoing debate over one type of mount vs another.
it is obvious to me as i am sure to others there will always be disagreement over which is right and maybe more importantly which is definetely wrong.
the basic problem with trying to get to something useful is one of variables, and the number one variable is the damned listeroid engine, no two are alike except in
looks
i might be successful in designing a building a system that is proven to work, but i wonder if it could be replicated by another, or even if i could replicate the result.
about the time that someone does develop and build a proven design, the next guy will look at it and say,, "well the plan calls for 2x4 tubing 1/4 wall, but i got a great deal on 3/16 wall and i am going to use it" the result may very well be something that does not function anywhere near the original design.
then if you look at the issue of balance, say the first guy spent a couple hundred bucks to get his engine balanced professionally, and noted that.. the next guy says hey mine is pretty good,, i am going with it,,, and the result will be different.
or yes the first guys rubber mounts worked, "but i found some surplus ones that look pretty close"
there will always be variables, and then factor in the variables of attitude, and you got a mess.
however there is a drive to try and prove the concept, if only for one engine
who knows if it could be duplicated easily with what we have to start out with, namely the lsteroid
one thing the concrete camp has going for it is consistancy, with one main variable and that being the subsoil.
a tough project, for a tougher group
bob g
ps. we do need a professor for "LIT" resilient mounting 101 :)
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Yep!...What Bob said.....you won't be able to design and build a Listeroid resielent mount frame buy the numbers that will work for any Listeroid! You need to know what you are dealing with before you decide to place your order for materials...steel or concrete. Also there is no way you can keep a jumper smooth without restraint or lots of mass directly bolted to it. You must have a smooth runner before you even think you know what mounts you need...the smoother it runs the less important lots of things become. So it really boils down to balance first and formost.......just my opinion. Been there done that!
Dave
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A thought about designing a mount.
Perhaps it would be easier to find out the speeds which are the smoothest and the speeds the engine hops the worst before designing the mount?
Although it is agreed to be unsafe to run the engine on the pallet, perhaps a wood frame that is more substantial could be attached, and the engine started at a slow speed. Then using a digital tachomenter, slowly increase the speed and write down in your engine logbook (you do have one don't you?) the speeds that are smoothest, roughest, cause the engine to hop up and down, twist, rock, etc.
I only suggest this because when I was de-rating my twin from 1000 RPM, I bought a 8.5" pulley from George B. After I put it on I started the engine while watching the cycles on the Kill-A-Watt. So the Kill-A-Watt became my tachometer, and I slowly reduced the engine speed toward 60 Hz. When the engine got to about 940 RPM it was running so sweet! But as I slowed it farther toward the (about) 735 RPM it runs for 60 Hz, it got to vibrating again, but not bad. As it settled in to 735, it was better. Actually it's quite acceptable now.
So my point is that each engine has a sweet spot(s), and probably a range of acceptable speeds as well.
If your knew what they were you would be able to decide if the engine really needs a massive concrete plynth, or could be mounted in the back of a small utilty trailer and taken on camping trips. ;)
Scott E
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Scott:
no self respecting research scientist at "LIT" would be without his engine log book, would he? :)
i think you are right on in determining the sweet spot for your engine and then designing around that spot, sort of like
working with nature rather than against it.
listers certainly have a nature all of there own, and each a slightly different nature.
might not be a bad place to work out dynamic balance from as well, would probably require less weight and less work to
really get one running very sweetly.
*side note, how bout them seahawks?? yessssss
bob g
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You must have a smooth runner before you even think you know what mounts you need.
I think this has been one of the basic parameters from early on in this discussion.
If you have a "jumper" that cannot be balanced by some pretty basic and inexpensive procedures you better bold it down to a large bolock of concrete. But it is also quite possible that "a jumper" is stressing a lot of components that a a well balaced engine would not be and so may not be able to provide the low maintenance longevity that those who buy these engines to put to work desire.
Balance would seem to be eqully important no matter how you mount the engine.
Using a large block of concrete simply allows you tro ignore the problem that imbalcane may be presenting in a less obvious manner. Why not also then ignore any of the other problems that may lead to shortened life and increased maintence as well ...rather than going to the trouble fo dissasembly and cleaning, etc. that is reccomended now.
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Dan.....
Thanks for the advice! I'll look into that as soon as I can! I'm sure it will save me lots of time and troubles!
Dave
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this thread was started by me, and seemed a fitting place to roll my tally to 1000 posts.
we have butted heads on this topic, one and all in some manner or another.
overall i think it was worth the effort, and perhaps all of us learned something from it
even if it wasn't "the" way to properly mount an engine.
i knew from experience that this was going to be a hotly debated topic, but i had no idea as to how
hot it would be. it also turned out to be the most posted thread to date.. i guess that is pretty cool in its own right.
bob g
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Welcome to the mile stone of 1K.
That and some cash might get you coffee somewhere ....but HERE you can receive the thanks and appreciation of all those you've helped with well thought out and interesting post.
Nothing beats experience in the long run. ;)
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Post more you two....
People are going to think I talk to much....
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This should maybe be in some other thread, but it does sort of pertain to this one.....
http://video.google.com/videoplay?docid=-7073987820618265400
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Man that is smooth.....
I mentioned in an email quite some time ago I was willing to pay extra if PEC could send rotating assemblies to a ballancing facility for work....
Atul rescently sent me an email that he was talking too and showing pictures I sent to an outside party about machining isues.
So....
Has PEC started farming out work the see can be done better than in house?
Does this mean that ballance and tollerence has become an issue?
Has the golden age of Indian Lister clones begun or is this just smoke blown up our collective back sides with a one off engine?
Doug
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The thing is that engine is just idling. Watch close at the beginning when it is doing full power, power strokes, load that engine up to its full power rating and that glass of water is not going to stay put very long.
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Its a start ain't it?
Some engines can't even run at idle like this.
Some like Gus ( also a Powerline product ) aren't even fit to run at all.....
Doug
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Andre,
load that engine up to its full power rating and that glass of water is not going to stay put very long.
That is absolutely true.Trouble is,I don't know of any way of balancing out the torque (reaction) pulses within the engine.Ok, maybe arrange a pair of singles with counter rotating cranks if your'e really keen! :D
Surely a well balanced engine at low rack opening (or spun by an external power source) is as good as you can get?
Ever sat on a BMW or a Guzzi annd blipped the throttle?
If there is a way, I'd love to know as I have a motor in pieces and will give it a go.
This isn't intended as criticism, I'll be the first to state that there are gaping holes in my knowledge. :D
Cheers,
Brian
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you will always have the torque and antitorque (countertorque for GuyF :) ) to contend with, but i still maintain that
this action can be mitigated by the position of the mounting system
the balance will remain the same regardless of load, but the torque action and reaction will change with variances in loading
i wish i had a single to work this theory out and prove out the concept
with the base mounting system, this torque action (and reaction) will cause the base to move as if the engine has balance issues
when (if balanced to begin with) it does not.
i would dearly love to see that engine in the film mounted to a cradle system and running at load, it would expect it to quiver a bit
but certainly no jumping up and down.
my business partner has a 10/1, maybe i can talk him out of it, or talk him into a teardown and balance, followed by a cradle mount system
just to see the end result.
the other interesting thing to note in the film is the engine does not seem to move in a piroette fashion, which tells me they have done a very
nice job of balancing that engine.
we now know what is possible as far as making a listeroid behave and sit still, it certainly would appear that the engine would not need anywhere near a ton of
crete to do a very nice job of running just fine, perhaps the 605 lb spec of the 5/1 would be more than sufficient.
i don't see any reason that engine could not be resiliently mounted and run just as long as it would if bolted to a block of stone. the result would be an engine that would not transmit much in the way of objectionable vibrations to anywhere else in the structure.
bob g
bob g
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I think it's their 8/1 internal balanced .. with water pump ,on their site it has holes drilled in the inside of the rim.. if so it's the one they used
n their biodiesel test...
{ I stand corrected It's a 6/1}
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Thats a 6/1 look at the wheels
tim
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so why do you think it's a 6/1/Tim??
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It has the spoke wheels . the 8/1 has 3 cutouts in the wheels, also its running close to 650 rpm .
tim
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mobile_bob,
This entire mounting theory is what I went through when building my diesel motorcycle and when anchoring the 6/1. Here are a couple of video clips of a one lunger in a cradle type mount that I believe illustrates your point as I understand it both now and back then.... I hope these will help.
http://www.diesel-bike.com/Diesel_Bike/farymann.avi
http://www.diesel-bike.com/Diesel_Bike/farymann2.avi
duh
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Duh:
while your clips illustrate the idea , clearly this is not exactly what i had in mind for a lister in that i would mount the cradle to dampen the rocking motion, but
one can see that the rocking motion is constrained as it relates to the crankshaft, the crankshaft in a proper implimentation is the center of the rocking component
and is stable and does not move.
with a well balanced engine the up and down movement is mitigated, leaving one to only have to deal with damping the rocking motion (component)
bob g
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Tim take look at these links
http://cgi.ebay.com/Lister-8-1-Slow-Speed-Diesel-Bio-diesel-In-Stcock-Now_W0QQitemZ330069433049QQihZ014QQcategoryZ106437QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/Lister-Type-Slow-Speed-Diesel-Engine-12HP-at-660RPM_W0QQitemZ290069980324QQihZ019QQcategoryZ11754QQrdZ1QQcmdZViewItem
Get the picture???
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the 8/1, 10/1 and the 14/1 all look to be the same picture of some engine, i don't think we can assume they all have the spoked wheels
as a matter of personal thinking i would be surprised if the 10 and 14 hp engines had spoked wheels
bob g
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12/2 (http://listerengine.com/coppermine/albums/userpics/10088/9728_1.jpg)(http://listerengine.com/coppermine/albums/userpics/10088/93cf_1.jpg)
http://volvoxengineering.com/GensetsSlow.htm
12/1 at volvox
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Its a start ain't it?
Some engines can't even run at idle like this.
Some like Gus ( also a Powerline product ) aren't even fit to run at all.....
Doug
But it is nothing new. In the last few years we have seen videos of the same thing being done by owners, some before and some after balancing.
As you hinted at earlier until this kind of balance becomes the standard, all this is, is one more video of an engine that is for some reason or other balanced better the most. :)
Could be some grunt was told to go startup every engine in the shop and bring the best one to the clean room to be filmed. That would be the old Chinese style of quality control, build a shit load of parts and sort out the good ones.
My engines are getting bolted to a big rigid block regardless. A resiliently mounted engine is useless if you want to use it to power something that is not also mounted to the same sub frame as the engine, like an overhead line shaft.
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It has the spoke wheels . the 8/1 has 3 cutouts in the wheels, also its running close to 650 rpm .
tim
I agree....the 12/2 shares the same flywheels as the 6/1 only one is keyed 180deg off. All of the larger HP Listeroids are internaly balanced so no external counterweight is needed and they are rated at higher RPM's.
Dave
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The 6/1 12/2 share the same flywheels ,the 8/1 16/2 share the same flywheels ,the 10/1 20/2 share the same flywheels . My flywheel broke on my 6/1 12 -7-06 with 3615 hours,took one off of my 12/2 it is now on my 6/1 same flywheels . The 6/1 12/2 are spoke 650 rpm the 8/1 16/1 are solid with 3 cutouts and run at 850 rpm, the 10/1/1 20/2 are solid with 4 large holes and run at 1000rpm not sure what dia, the 8/1 16/2 are. Also have a 10/1.
tim
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The 6/1 12/2 share the same flywheels ,
tim
Tim,
Take a look at your 12/2 for me. Either it has one Flywheel keyed 180 deg. off from the counter weight or the cranks keyways are 180 deg off...which do they do? I don't own one yet.:)
Dave
Added
This 12/1 the keways are inline and one flywheel is keyed off 180degs.....you must have grabbed the correct one or it would have been a real jumper!
(http://listerengine.com/coppermine/albums/userpics/10088/9728_1.jpg)
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Wrightkiller's pics shows a staggered keyways. That would make sense, otherwise somebody is SURE to reverse them.
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Hotator,
Do we see the same thing? It appears the crank keyways are inline and one of the flywheels is keyed 180 off...if you swapped them ...........big jumper! Or I'm not see it correctly which is quite possible
Dave
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Dave
I took it off the same side,it was the starting side wheel that broke. Didn,t make any difference in balance. Still as smooth as before
tim
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Dave--
I've blown it up until the pixels look like a concrete block wall....looks to me the keyways are up on one side and down on the other.
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Dave , Jack
The wheels on the 12/2 are keyed the same as the as the 6/1 . I,m not sure but this might be where some of the inbalance comes from , the keyway may be off just the tinest bit just enough to throw them out of balance.
tim
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Thanks Tim and Hotator,
I know they had to do somthing there to use the same flywheels...on both. I thought I remembered George talking about a 12/2 with keyway off 180 or it wasn't and it was a jumper could have been a different issue. Alot safer with all the 650 RPM wheels the same!
Dave
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Guys I hate to be a pain in the a$$ but this is the only good pic of a 12-2 crank I could find
(http://listerengine.com/coppermine/albums/userpics/10081/12-2crank.JPG)
Is there a keyway on the right side?....
Now what?
Dave
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Looking at my original 12/2, the keyways are on in-line on the crank, the flywheels are keyed 180 out (wrt to the counterweights); if you are facing the intake/exhaust side of the engine, the right flywheel key is (more or less) on the same side and centered with the counterwieght, the left flywheel key is (more or less) opposite the center of the counterweight.
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MikeyT---
Thank you for that. Its' absolutely staggering that they would DO such a thing, but thanks anyway.
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Tim,
Check out your other fly wheel on your 12/2 before you use it on a 6/1. I can't believe it either!
Dave
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Peter had some comments regarding this and pictures of both twin flywheels a while back,
see here: http://listerengine.com/smf/index.php?topic=1119.msg14608#msg14608
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Dave
The other flywheel is different its keyed 180 degrees out . Jez that would make a jumper. The one on the starting side is the same as the 6/1. :-[
tim
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I don't know why they did that....it is the easy way for sure but could be a big problem. Setting up the 12-2 crank and putting the keyways in at 180 would make all the flywheels the same on 650 RPM engines and eliminate a big boo boo..
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I'm with you, Dave.
Can you imagine someone finding two old 12-2 wheels for their 6-1 and BOTH be wrong!
Murphy is dancing a jig.
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They'll be fine as long as they use the requisite 2 tonnes of concrete as the mount.
That's what it was originally for, wasn't it? To hide Lister's terrible quality control?
Come on, we all know that's the truth.
;)
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After seeing the redryder engine, it seems pretty apparent that a ton of crete may not be necessary at all.
been altering the frame design a bit
http://listerengine.com/coppermine/displayimage.php?album=random&cat=0&pos=-541
(this is a rough sketch of concept only, dimensions are not to scale and placement maybe altered)
with the latest evolution, i have moved the genhead off the subframe so as to keep the engine in the center of the subframe, and thus
keep the centerline of the crankshaft centered in the cradle.
with the genhead base plate mounted to the top of the cradle the weight of the generator works to bias the
stronger countertorque (anti torque to the english) of the power stroke,
sorry for being a pirate and taking the discussion back to the original topic :)
one pirate to another i guess
still playing around with idea's and design alternatives here
bob g
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Sorry Bob!
I guess we at least kept it about Listeroid balance and not putting a 6/1 solid rocket and a 12/2 solid rocket on the space shuttle with a cox .049 to compensate for the inbalance... :D That was a joke! ;)
Dave