Lister Engine Forum
General Category => General Discussion => Topic started by: mobile_bob on October 04, 2006, 03:59:04 AM
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I would like to submit the following for everyone's consideration, this post is not to suggest any
way over another of mounting an engine. It is basically the most coherent analysis of what has been discussed that I can come up with. I will try to break it down into components, sometimes simplistic and at other times a bit more complex, in the effort to try and pull the discussion together.
There are two opposing sides at play here, (1) the use of concrete as the only way to mount the engine, and, (2) an alternative method using steel and resilient mounts
In the following paper I will attempt to examine critically both positions, first stating the position
and then examining the position and determine support for that position.
A. "Mr. X supports the contention that lister only specified concrete as the material of choice for mounting the engine, "
To date I have seen no documentation as to why the concrete block was to be used, only that it must be used to support the warranty. By documentation I mean supporting engineering text that clearly shows the need for the concrete base, not advertising literature but the math and physic's to support its use. Lacking such documentation one cannot assume whether the use of concrete is mandatory or not from an engineering standpoint.
B. "Mr. X further contends that lister made no recommendation as to the use of anything other than concrete, and specifically that they never mentioned the use of resilient mounts."
Just as in (A) above I have not seen documentation that lister even tried resilient mounts.
Again without supporting documentation in engineering terms we cannot assume that the use of resilient mounts are inherently good or bad.
C. "Mr. X further states that the concrete block was an integral part of the design of the engine"
Here again to date I have seen no documentation that the concrete block was an integral part of the engine design. Further anything that is bolted rigidly to the crankcase becomes part of the crankcase for purposes of transmission of vibration, resonance, and vector analysis.
Examining the contention that the concrete block was an integral part of the engine design the engineers in their wisdom would have had to work out all the math/physic's of a number of parameters all based on the specific use of the concrete base.
The problem with this contention is the same engine crankcase was also used on the SOM wherein a cast iron base (which bolted to the engine block become part of the crankcase) is used as an intermediary component between engine and concrete block. The use of a cast iron sub frame would require differing physic's, vectors etc. to enable the concrete to still become part of the crankcase. This assumes the contention that the block of concrete was an integral part of the design.
It therefore cannot be an integral part of the design of the engine, because both engines whether mounted directly on concrete or mounted to the concrete via the cast iron base are the same engines, using the same castings.
So can we assume that the use of concrete as a mounting base is or is not the only way to mount it? No
Does it allow room to explore other possibilities of mounting? such as resilient mounts? Yes
Now the opposing side
(D) Mr. Y contends that much has changed technologically in the last 50 odd years
Mr. Y, needs to understand and accept that while technology has advanced the basic physics have not changed. Materials in some cases have changed, but cast iron is still cast iron today as
it was 70 years ago. Resilient mounts while made of better material today follow the same physic's they did back then. Very little is truly new, and practically nothing related to these engines is any different today than it was 50 years ago.
(E) Mr. Y contends that the engine can be mounted on a steel frame with resilient mounts
While anything can be mounted to anything else with sufficient effort, Mr. Y should be aware of the problems he will encounter in doing so. Should the engine be bolted to a substantial steel sub frame with quality components and then bolt the sub frame to the concrete base, technically he should have no problems or safety issues. Basically he will have a steel SOM base. Which arguably may be superior in strength to the original SOM cast iron base.
The problem however arises with the use of resilient mounts and the stresses that will be imparted back not only to the steel sub frame but to the engine block itself. Remember the steel sub frame is now part of the crankcase.
Resilient mount positioning will be critical, and should be in line with the plane of the crankshaft, not below the crankcase as is typically described by those wishing to use this method of mounting.
The question then arises on how to raise the centerline of the mounts to the same plain as the crankshaft centerline? This is where one can get into all sorts of trouble, this is where the highest stresses will be transferred. That being the transmission from the lower frame mounts to the risers. Presumably one would have to weld the frame risers unless he can have the side rails of the steel sub frame mandrel bent to raise the mount to the centerline of the crankshaft. These welds will have significant stresses imparted on them, and over the course of time will likely fatigue and fail if not properly designed and executed.
Also it is well worth noting that the engine will exhibit what is known as "critical speeds" which in stationary use the engine should not be running in. These critical speeds are evident when spinning up and down of the engine it passes through rpm ranges where the vibration and stresses are dramatically higher than at rated speed. Provisions have to be made to limit this mode of operation and to provide a measure of additional support for the engine while in the "critical" engine speed range. This adds another layer of complexity to the design.
in conclusion:
there is no clear evidence that the use of concrete is an integral part of the engine design, further there is no evidence that supports that it is the only way to mount it. Clearly the use of concrete has proven to be a time proven design, a safe design that works. It has proven to not have any detrimental effect on the engine and it could be argued that it has improved longevity of the engine, even though no studies have been done.
The use of a steel sub frame that is securely mounted to the concrete block should provide a safe and sufficient mounting for the engine, that is well within most DIY'ers capabilities. Also the use of relatively thin and dense pads should cause not adverse effects on either the engine or the safe operation of the engine, although not providing much in the way of abating the transmission of vibration.
The design, manufacture and use of a steel sub frame and resilient mounts should be possible provided that the design is well engineered and fabricated following accepted engineering standards. It is my conclusion that this may be well beyond the capabilities of the average DIY'er.
My hope in presenting this thread/post/paper is to cut through the feeling, thoughts and conjecture that has been prevalent in the discussion, and to narrow it to the basics at hand.
Again I am not going to suggest one method of mounting and engine over another. Should the end user of an engine not feel he understands fully the forces at play I would strongly suggest the use of either concrete direct mounting or a steel sub frame directly mounted to the concrete.
hopefully this will be accepted by all in the spirit it was written
I invite constructive criticism, thoughts and questions, and of course opposing views :)
bob g
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I don't get it Bob.
Without a doubt the technology has advanced since the age of the Lister. Kubota and others make excellent diesel engines which use convenient flexible mounts.
The designer of the engine we all revere plainly specified the use a concrete block. Does it make sense to revere the engine but regard as quaint the designer's installation instructions?
Hotater learned the hard way to use a block, and documented it clearly.
I guess in his passion Guy overstated the risk of out-of-spec mounts. Still, if you believe this old technology is still vital, why do you believe the mount is old fashioned?
Surely there's a place for alternative mounts, maybe in the majority of situations. How many of us are off grid? Of those, how many really need tens of thousands of hours out of these engines? If you want to do it right, though, it's hard to imagine a safer bet than following the manual.
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Pro:
what don't you get?
maybe it is just late, and i am too tired, but you seem to be on both sides of the issue, or am i missing something?
i wrote a responce to your reply, but after doing so i scrapped it because you appear to be back and forth a bit..
please clarify, is there a problem with my original post?
specifically?
bob g
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what don't you get?
maybe it is just late, and i am too tired, but you seem to be on both sides of the issue, or am i missing something?
You're right, my post was confusing.
What I meant was, I've read lots and lots of discussion about how to mount Listers, but IMO if you want to do it right, RTFM.
If you want to reap the fruits of modern technology, get a Kubota. They're wonderful, and easy to mount. If you want to pursue time-tested engineering, then do just that.
RA Lister's glory occurred at a time and place where one might expect to use a stationary engine for decades and to pass it along to kin and to run it for tens of thousands of hours. That's vanishingly rare in our place and time. If you won't run an engine for more than a few thousand hours, it likely won't make much difference how you mount it, so sure, take a shortcut -- but don't fool yourself that you're doing it right.
What I don't get is all the discussion about the right way to do it, the right way is plain as day.
I'd been holding off on making that post, but when this new thread opened I went ahead. I wish I hadn't now that I think it through though; I didn't say anything novel. Sorry for diverting your thread.
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Well here's what I think. It really doesnt fucking matter how you mount your engine as long as you are happy with the way you mounted your engine. Im sure Hotater has a true sense of pride in a job well done, it was a huge effort and hopefully satasified his fondest mounting desires.
Screw the manual's mounting reccomendation that shit is so damn antiquated at this point in time to me its not even funny. Ill mount my engine on what will stand my willie and statisfy my fondest mounting desires and that will be on a set of modern air filled industral mounts made for machines like hammer mills and other ultra heavy duty equipment. The added peace from a vibration free setup by far out weighs the minute chances of catastrophic simultanious multiple mount failures.
Peace&Love :D, Darren
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A. "Mr. X supports the contention that lister only specified concrete as the material of choice for mounting the engine, "
To date I have seen no documentation as to why the concrete block was to be used, only that it must be used to support the warranty. By documentation I mean supporting engineering text that clearly shows the need for the concrete base, not advertising literature but the math and physic's to support its use. Lacking such documentation one cannot assume whether the use of concrete is mandatory or not from an engineering standpoint.
Correct.
However I very much doubt you have seen "maths & physics" like this from any engine manufacturer, I'll lay money on it.
So to put this in perspective there is nothing unusual going on.
B. "Mr. X further contends that lister made no recommendation as to the use of anything other than concrete, and specifically that they never mentioned the use of resilient mounts."
Just as in (A) above I have not seen documentation that lister even tried resilient mounts.
Again without supporting documentation in engineering terms we cannot assume that the use of resilient mounts are inherently good or bad.
Lister were in the business of selling engines, you can assume that they would do nothing to limit the possible market by arbitrarily omitting to mention certain installation options, particularly as said options were common across other models in the range.
C. "Mr. X further states that the concrete block was an integral part of the design of the engine"
Here again to date I have seen no documentation that the concrete block was an integral part of the engine design. Further anything that is bolted rigidly to the crankcase becomes part of the crankcase for purposes of transmission of vibration, resonance, and vector analysis.
Examining the contention that the concrete block was an integral part of the engine design the engineers in their wisdom would have had to work out all the math/physic's of a number of parameters all based on the specific use of the concrete base.
The problem with this contention is the same engine crankcase was also used on the SOM wherein a cast iron base (which bolted to the engine block become part of the crankcase) is used as an intermediary component between engine and concrete block. The use of a cast iron sub frame would require differing physic's, vectors etc. to enable the concrete to still become part of the crankcase. This assumes the contention that the block of concrete was an integral part of the design.
It therefore cannot be an integral part of the design of the engine, because both engines whether mounted directly on concrete or mounted to the concrete via the cast iron base are the same engines, using the same castings.
So can we assume that the use of concrete as a mounting base is or is not the only way to mount it? No
Does it allow room to explore other possibilities of mounting? such as resilient mounts? Yes
You have an extra undocumented assumption or two in there, some of them are patently flawed.
a/ the size of block used for a s-o-m base will be much larger than a block used for a pump base.
b/ listeroids ship the bare motor, lister very very rarely shipped a bare motor unless you were an OEM, just about everything came on some sort of iron or steel base.
c/ the documentation that I provided for download was for a start-o-matic as well as the bare cs 6/1, both specified the concrete block
d/ nobody has looked at a lister base, eg nobody has opened their eyes.
Bob, I as you know don't know dick about you, I don't know if you have a single qualification to your name or not, what I do know is what I have observed, you work your way methodically through problems and you don't skip steps unless you don't see them, and even then you will look backwards now and again in case you missed something.
The lister bases, whether iron or steel, were a honeycomb when viewed from underneath, you are smart enough to work out why.
Nobody has ever asked me if I ever did or saw done any analysis of the loads on a lister, there is a pretty big clue in the four 3/4" bolts lister used, guy incognito is in between branding me a luddite playing with spreadhseets and coming up with forces of 150 kilos on the engine mounts, and slightly worried by it, y'all could have asked me because I have seen these tests done with proper strain gauges and data capture on a 6/1 driving a hydraulic pump under the full range of loads, and guy incognito is nearly an order of magnitude out, I saw amplitude ranges of in excess of 1000 kilos under certain conditions, and some of the second and third order harmonics of these loads were a bitch too..... again, those 3/4" bolts lister used make a lot of sense if you look at them with an open mind and let what you are looking at seep in and percolate.
The concrete block also allowed you to follow lister directions and leave the top few inches of bolt free and unfixed, so those loads are spread along a length of bolt instead of being concentrated in one point, all for fatugue see.
If you have an engine that is dancing, eg an engine that you can stick a feeler gauge under when it is running, then by definition there was enough force reacting on the engine to reduce its effective "weight" to zero momentarily.
Scott doesn't like the vibes, a 70 kilo man stamping his feet in turn can produce 100 kilo impacts each foot with no great effort, and you won't hear that vibration, or feel it, any distance away.
There is this disconnect between what is literally staring people in the face, and what they think they see.
The "errors" introduced ALWAYS scale the problem down, that is human nature. The engineer has to consider these factors.
You will "get" it bob, the penny is dropping already to coin one phrase, and to coin another keep at it and you will hear the sound of the other shoe falling too.
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boy oh boy,, this cracks me up :)
or rather proves out a contention that Guy has made all along, that being folks will read something and take from it just what they need
to support whichever direction they were going in the first place, however out of context thier take might be.
i gave that post some time and some serious thought, and quite frankly i am quite amazed at some of the responces, but that is ok.
at least it narrows the scope to perhaps some specifics that i am still questioning and might prove educational to some.
Guy:
i accept the use of concrete, because of empirical evidence, not engineering evidence.
if you would further like to discuss and enlighten me in this regard, please do so, really i am very interested.
Darren:
chill out my friend, the post was never intended to piss anyone off, rather to tighten the discussion
and to perhaps get to a few answers. Surely you are smarter than that.
Pro:
thanks for clarifying your position, i was unsure with your first responce.
i would suggest you go back and reread my conclusion, yes the concrete block is the default mounting method
and for good reason, that being "empirical". At least for now, or until the discussion proves otherwise.
it is plain as day that this subject has become one of the group
that being subjects you don't discuss in polite company,
"religion, politics, and lister/oid mounting"
bob g
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Pro:
thanks for clarifying your position, i was unsure with your first responce.
i would suggest you go back and reread my conclusion, yes the concrete block is the default mounting method
and for good reason, that being "empirical". At least for now, or until the discussion proves otherwise.
I re-read your conclusion Bob, but for my final remark on the topic I can only repeat that I don't get it. There is possible utility in a thread along the lines of, how much of a shortcut should I take for X requirements?, but RA Lister's manual incorporates millions of hours of runtime, years of engineering, and untold failure analyses. How much weight can our armchair discussion have exactly?
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Pro:
that is the fundamental difference between you and me i suppose.
you accept as fact because that is what you are told or read, i accept what as fact, only after scrutinizing what i have been told or read.
we both come to the same conclusion although from different approaches
again i accept the solution, but do not accept as of yet the reasoning as being fact
Basically if the answer is concrete, then i want to see the calculations or the lister work that brought them to their conclusion.
this is no different than Guy asking Guy Incog for his math to support his contention that a particular resilient mount will work.
GI asserts that abc mount will work for the intended purpose, and Guy asks to see his computations. That is fair is it not?
so conversely
if Guy asserts that xyz mount will work, then i should be well within reason to ask to see the computations, That too is fair is it not?
bob g
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Last week I spoke with a mechanical engineer about using resilient mounts for a Lister type engine. He said it should not be a problem, I sent a sketch of the frame the engine would be mounted to. This sketch shows cross bracing and additional widening of the footprint that are not part of the base in the video I put on Google. Once I have something from him I will share it.
One of the members did not give this plan much credence because I am not an engineer and thus am not qualified to know if what the engineer comes back with is worth anything. I completely disagree but let’s just assume that is the case for now.
I decided to get the answer from the most qualified to discuss this topic, the Lister Petter company. I called Lister Petter today and spoke to a member of the engineering department. I explained that I wanted to mount a 6/1 engine to a rigid steel frame and mount the frame using resilient mounts to the slab of a garage. (I used a 6/1 as an example because it was easier than trying to explain the Lister/Listeroid issue, and I will have a 6/1 in about 60 days) He said as long as the frame is rigid he sees no reason why that would not work. He suggested I talk to a company they use called Ebco http://www.ebco-inc.com about which mounts would be appropriate for my situation.
I am sure there will be people who are skeptical of the account of a phone conversation I had, fair enough. I will e-mail the sketch of the frame to the engineer tonight and will post the reply from him (and he better reply)
To recap I have spoken to 2 engineers and both said mounting could be done with resiliant mounts. Granted this is a small number and will likely be dismissed as too small of a sample, how many would be an acceptable sampling?
Perhaps this will shed additional light on this subject and maybe, just maybe put it to bed once and for all.
Naaah I have a feeling the beat will go on.
Scott
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very fascinating Scott
would be quite interesting to get an email from lister petter outlining the possible use of a rigid subframe and the use of resilient mounts...
if he was to look over your sketch and approve of it at least in principle and email you back. hmmmm
i guess that might change the hue of the debate a bit.
very interesting
bob g
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That assumes there is anyone still working there that knows anything about the dynamics of one-lung engines. That was a product that was in its prime 50-70 years ago. As the market moved toward smaller displacement, multicylinder higher RPM engines, the guys who really understood what was going on with the rock-crushers probably found no one to pass their wisdom to, save an occasional sympathetic barkeep in the pub down the street. When contacting manufacturers about legacy products I've learned they sometimes tell you what they think you want to hear just to get you off the phone. So as always, keep yer eyes open and don't pass up the opportunity to scrutinize advice (mine included, I suppose).
Quinn
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So as always, keep yer eyes open.
Quinn
You got that right Quinn! I have been watching both sides of this issue for some time and even participated in some of the discussions....There are several Listeroids out there doing there little jiggle on rubber do dads and doing very well...I have one...I'm not the only one for sure...My point is I can show how it works with a balanced 6/1 and all I have asked is where are all of the broken cranks....60-70 years is a long time to break a few....Not someones theory.....Facts work well! No one has as of yet has shown us what a original CS 6/1 Lister looks like running on cement loose..! I would love to see how well they are really balanced! That would help alot in explaining to me why they recomend there mounting procedure. I wanna know!.....Fact is balancing cost money...pay more for the product!....cement was cheap.....thats my theory! The math is called the bottom line...still used today!
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that is the fundamental difference between you and me i suppose.
you accept as fact because that is what you are told or read, i accept what as fact, only after scrutinizing what i have been told or read.
I'll assume you didn't intend to say that I am an idiot and you are not, but you did.
we both come to the same conclusion although from different approaches
My conclusion is that it is presumptuous to question RA Lister's competence.
again i accept the solution, but do not accept as of yet the reasoning as being fact
Not sure I understand.
Basically if the answer is concrete, then i want to see the calculations or the lister work that brought them to their conclusion.
this is no different than Guy asking Guy Incog for his math to support his contention that a particular resilient mount will work.
GI asserts that abc mount will work for the intended purpose, and Guy asks to see his computations. That is fair is it not?
so conversely
if Guy asserts that xyz mount will work, then i should be well within reason to ask to see the computations, That too is fair is it not?
If you're curious, more power to you. If you doubt the CS design, then the burden of proof is on you. As stated above, the CS has millions of hours of runtime and years of engineering. You could equally well assert that the crank diameter is wrong or the number of teeth on the idler gear or the tappet face size, and ask for proof to the contrary.
As far as finding experts that repudiate the CS manual, well sure you can find them. With enough effort you'll find an ME who recommends doughnuts for mounting your engine. Experts designed the Tacoma Narrows bridge, too. If you're sold on the CS, why not listen to the engineers that designed it?
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Ok, I'll post a few things here - I was going to reply to you about these things in my resilient engine mount thread Guy_F, but I don't want to clutter it. Lord knows its cluttered enough already.
Nobody has ever asked me if I ever did or saw done any analysis of the loads on a lister, there is a pretty big clue in the four 3/4" bolts lister used, guy incognito is in between branding me a luddite playing with spreadhseets and coming up with forces of 150 kilos on the engine mounts, and slightly worried by it,
If you'd care to read my thread completely, that 150kg was for a guesstimated piston imbalance only.
Not rotating imbalances.
Or torque reaction.
Or any other force that I can't think of off the top of my head. I'm sure there's a few more. Enlighten me if you know.
y'all could have asked me because I have seen these tests done with proper strain gauges and data capture on a 6/1 driving a hydraulic pump under the full range of loads, and guy incognito is nearly an order of magnitude out, I saw amplitude ranges of in excess of 1000 kilos under certain conditions, and some of the second and third order harmonics of these loads were a bitch too..... again, those 3/4" bolts lister used make a lot of sense if you look at them with an open mind and let what you are looking at seep in and percolate.
I have asked you. I've asked for figures and data to back it up, in quite a few block vs rubber threads. and just NOW you're suddenly pointing out that you've done all the practical work that I'm trying to encapsulate in theory? You could have used that last paragraph as a powerful rebuttal to a number of arguments about the safety of concrete vs resilient mounts..... but you didn't. Why? And out of interest, where where the sensors located on that system?
The concrete block also allowed you to follow lister directions and leave the top few inches of bolt free and unfixed, so those loads are spread along a length of bolt instead of being concentrated in one point, all for fatugue see.
Good, good. So there's a bit of give between engine and concrete? I thought this thing was a rigid mount? You know, if there's give, there's a spring factor, and if theres a spring factor.... it's a resilient mount. Of sorts.
If you have an engine that is dancing, eg an engine that you can stick a feeler gauge under when it is running, then by definition there was enough force reacting on the engine to reduce its effective "weight" to zero momentarily.
See above comment. Does that mean I could calculate the spring rate of the 4 bolts and show you where the resonant frequency is? Picking a ludicrous (for resilient mounts) spring rate such as 2MN/m gives me a resonant point at a range of figures between 400-800RPM depending on damping and whether power pulses are the dominant driving force under full load. Ring any bells?
In any case, reducing it's effective weight to zero is a heckavalot of force in anyone's language. Are you sure that thing was really balanced well? Just makes me wonder about the "bung it on a two ton block, the sucker won't go anywhere then" theory as being the default for lister because they didn't care much for engine balance.
(edit: bloody nested quotes, again.)
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i am doing my level best to keep my cool, but my patience is being tested
but that is ok, it has been tested before and it will likely be tested many more times before i croak.
i am really tired of the original lister being put on a pedestal as being the most fantastic of all man's creation.
it is no ferrari, it is no rolex, it is no manhattan project of internal combustion engines.
what it is, is a successful design that had a long production run, yes it was a mass produced engine and as
such had short cuts taken with it as well, anyone that doubts this is clearly lieing to themselves.
last week on this very board a member posted a picture of the assembly line at lister, showing a bellbottom dude
assembling his part of the engine.
if you look closely you will clearly see the crankshafts have been installed, but nowhere in the picture are the flywheels in view.
any finely balanced engine has to have its flywheels balanced along with the rest of the rotating assembly, such as crankshaft, rod, piston, rings, brgs etc.
anyone that has had the components of his engine balanced by a reputable shop will know that if you replace any part of the rotating assembly the whole thing has to be done again.
also there are reports from folks starting their engine on the crate and having it sit there and purr away, obviously pretty well balanced either by design or accident. and also reports of the engine started on a pallet, trying to jump all over the place and scaring the crap out of the poor guy that got in a hurry to start it,, obviously a poorly balanced engine.
if it will run on a pallet then it will run on resilient mounts, period. Conversely if it jumps all over the shop, then bolting it to concrete is not the solution but a bandaid fix. you can argue theory and math all day, but this is fact.
these engine just like every other production engine of mass production were balanced as well as need be, at a cost.
clearly when you do so there will be a few that fall outside good balance and also a few that are exceptionally balanced.
the ones in the middle are adequately balanced to mount to a concrete block and run forever, even the ones that fell outside the range of acceptable probably ran forever also anchored to concrete.
why did they specify a concrete base, pretty damned apparent to me, and should be apparent to anyone with a reasonable intellect.
also when these engines were first designed and put into place, the normal way to mount them was on a concrete block, didnt make a difference who's engine it was, most everyone mounted to concrete as it was cheap and easy to put in place.
they followed a hundred years of stationary engines being mounted that way, was accepted by the buying public as normal, so why reinvent the wheel.
one should also accept the fact that it was not at all common for end users to have at their disposal arc, mig, tig or other methods of welding up a framework, and while there were rubber mounts they were not as numerous or widely available.
going back to the balance issue, if the original engine was a rolex, and finely crafted and finely balanced, then the flywheels would not be interchangable, and one would not be able to just order up replacements.
in closing,,, the original engine was a fine engine, did its job very well
the listeroids can be made to be very near if not the same quality of an original.
as for mounting,,, if you believe it has to be mounted to concrete, then by all means do so, and god bless you,
i have never argued against this form of mounting, but i assure you that i damn sure could and be able to document my
reasoning against it.
but...
don't tell me that it is the only way a well balanced lister/oid engine can be safely mounted, and further don't tell me the engine life will be shorten because of resilient mounting if it is engineered and implimented properly.
i feel better now
bob g
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i feel better now
bob g
I may not say it in the same terms.....but I agree 100% on the reason why they had a specific mounting method...You pretty much said it all!....now lets balance them thumpers!
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Pro:
"I'll assume you didn't intend to say that I am an idiot and you are not, but you did."
if you took from my statement that i think of you as an idiot, i truely am sorry, that was not my intension.
when i stated:
"you accept as fact because that is what you are told or read, i accept what as fact, only after scrutinizing what i have been told or read."
i was simply trying to illustrate two differing ways of looking at the same information.
believe me i have fallen into the same trap myself many times.
as you are probably aware one of my pet peeves and something that i have spoken against for many years are products
such as desulfators,, if you read the manufactures paperwork, documents etc you will be lead to believe that these things not only work but your expensive batteries will die a horrible and premature death without the use of their machine.
i am not here to say that the folks that manufacture and sell desulfators are on a par with the fine folks at lister, that is quite aside the point.
i just have to use the same level of scrutiny with lister publications that i would with the desulfators or magnets you put on your fuel line, or copper bracelets,
assuming that lister was the premier engine builder of the day, that does not make them above question.
today catapiller is a huge engine builder of world fame and they too make mistakes and omissions in their documentation.
as an example just the other day, when faced with a 3126e cat with electronic control problems with the intake heater
i went to cat to get the schematic,, after analizing the schematic it became apparent that it was flawed, seriously, the system could not function as descibed..
i went to the tech guy who called the factory tech guy, who asked "who the hell is this guy. mobile bob?" what the hell does he know? we have had this in production for the last 8 years! "
when i was given the phone it took exactly 1 minute to show him the flaw!
he got a whole lot nicer to me.
so i don't automatically accept anything in print as being gospel, unless i see moses coming down the mountain with the stone tablets.
what i will accept:
good documentation that will stand up to a modecum of scrutiny at the very least, followed by
other examples of the principle from other sources, if then
i see sound reasoning, by at least 3 sources (not connected to the originator of the claim) to substantiate the claim
then i feel pretty confident that the claim is valid
short of that, it is just that a "claim"
again i appologize if i implied you to be an idiot
bob g
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I didn't take offense Bob, I pointed it out so the other kids won't think I'm a pussy.
A while ago I ate a large Philly cheese steak and fell asleep on the couch. I had a vivid dream wherein I was standing in a Dursely breakroom in front of a blackboard. Seated in front of me was Harry Ricardo and a team of RA Lister engineers. One of them said dryly, "Tell us how your flexible mounts are better than concrete." I gave it my best: the promise of the future, the forthcoming advances in mount technology, I even hinted about nanotechnology. Then out the corner of my eye I noticed a troublemaker in back touch his thumb and index finger together and make a very rude gesture. They all laughed at me. Bastards.
Ricardo cleared his throat and stood up, and the others quieted down. He said, "I have a piece of advice for you." He called me "young fellow," which is a lie but not one I mind hearing. I was delighted to be in the presence of this great man, and the wait for this pearl of wisdom was long. It was however worth the wait. "Keep it in your pants" he said, then he turned and walked away. Don't try to tell me you haven't learned this lesson the hard way. He was a great man.
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"keep it in your pants" Gord you blokes go on with some crap!! Just fired my J (on skids) no jumping, no vibration, no concrete, no bloody rubber mounts. It's 79 years old, hasn't run for fourty odd, and fired up first go, DONT rubbish Lister to me,
BK
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"keep it in your pants" Gord you blokes go on with some crap!! Just fired my J (on skids) no jumping, no vibration, no concrete, no bloody rubber mounts. It's 79 years old, hasn't run for fourty odd, and fired up first go, DONT rubbish Lister to me,
BK
Who's rubbishing Lister? The pants remark was joke, and didn't have anything to do with Listers actually. I started out writing yet another restatement of my position on the mounting issue, and was overcome by the futility of my efforts. So I wrote something silly instead. About going on with crap, though: guilty as charged.
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I did a tour of shops today getting quotes for ballancing and amchine work.
Nordic engine here in the Nickel City quoted me between 150-200 CDN for a complete ballance of all the rotating assembly including fly wheel, face plate addapter output shaft and a free polish....
For that kind of money you'd have to be a real cheap fello not to get all you mass spun and checked. Then mount the bugger on solid foundation.....
Doug
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I did a tour of shops today getting quotes for ballancing and amchine work.
Nordic engine here in the Nickel City quoted me between 150-200 CDN for a complete ballance of all the rotating assembly including fly wheel, face plate addapter output shaft and a free polish....
For that kind of money you'd have to be a real cheap fello not to get all you mass spun and checked. Then mount the bugger on solid foundation.....
Doug
Best bang for the buck! I'm going to do the same with my second 6/1....turns them into a Honda 6/1...:)
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I didn't tell them it was a clone but rather an old engine with new parts made in India.....
No one loves a cheap crap clone. But tell a trades person your trying to restore something and ears perk up. Dare I say it a little white lie gets better deals and perhaps a little more sympathy to correct defects.
Doug
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Pro:
i regard to "keep it in your pants" story
didnt your momma tell you not to lick your fingers after you were serviceing the batteries?
i thought i had weird dreams :)
bob g
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I used to dream about wiring machines in a factory where I worked. I would mumble in my sleep and ,y hands would move.....
My wife would elbo me and tell me I was wiring in my sleep again. I'd thank her for waking me to tell me that and roll over go back to sleep and try and remember where I was before she broke my concentration.
True story.
Doug
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Can this issue be put to bed now?
Below is my e-mail to the Lister Petter company
Greetings
I hope you can help me determine the best way to mount one of your engines. The engine in question is a Lister cs 6/1 with a SOM cast iron base. They have not been manufactured for a number of years, but they are quite sought after in the used market. I would very grateful to get the professional opinion of someone from your engineering team as to the best way to mount this engine.
I have read that the original mounting system was a cubic yard of concrete. My hope is that technology has advanced to the point where resilient rubber type mounts could be used which would offer the benefit of vibration isolation. I have looked into this type of mounting system, the engineering staff at the various companies say their products can be used, I thought it would be a good idea to check with check with your company first.
Best regards
Scott"
Below is the response from the company
Scott,
This as you will appreciate is a very old engine and the only recommendation
that was made by us in those days that I can find was to mount these
solidly.As you rightly say technology has moved on and I do not doubt now
that some form of resilent mounting could be used providing good engineering
practices are adhered to.Although do bear in mind that as the engine only
runs at about 600rpm and really at that speed provided the mounting is flat
and square very little vibration will be produced.
Regards
Phil Downes
Applications Manager
Tel. +44 (0)1453 541068
Mob. +44 (0)7712 085163
Fax. +44 (0)1453 541103
The above is not from the engineer I spoke with, I have not heard from him yet. This is a response from an e-mail I sent to the co from their website link.
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Can this issue be put to bed now?
....
Below is the response from the company
...
This as you will appreciate is a very old engine and the only recommendation
that was made by us in those days that I can find was to mount these
solidly.
He doesn't pretend to be an expert, Scott. Evidently he didn't take the time to read the manual or couldn't find a copy. I don't regard that as a strong argument, much less a definitive one.
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Procrustes
You quote the part of the conversation, which supports your view, while omitting the part below, which does not.
“……As you rightly say technology has moved on and I do not doubt now
that some form of resilent mounting could be used providing good engineering
practices are adhered to….”
I don’t think anyone ever said that a big block of concrete was not a suitable mount. The question was, is it the ONLY suitable mount? The information is accumulating that says it is possible to mount a Lister type engine on resilient mounts. This info is from the opinions of two engineers I spoke with, in addition to the opinion of this person at the Lister Petter company.
Everyone is entitled to his opinion; I give more weight to those from people who are experts in their fields, in this case the engineers and this representative of the Lister Petter company.
Take what you want from the reply.
Procrustes what exactly would you need to see to convince you that a resiliant mount is acceptable, Just curious?
Scott
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In another thread I have listed links to papers dealing with the design of machine foundations. I have not had a chance
to read them yet so can't say how useful the information is.
The link: http://listerengine.com/smf/index.php?topic=1097.75
Don't want to "take sides" in the rigid vs resiliant engine mount debate, but only provide information I found in .pdf
copies of original Lister manuals found on the internet and that I saved. I have seen the recommended design for the
engine foundation in the manual that came with my Metro 6/1 and suspect that it is the same as the Lister standard
engine foundation, but I would love to see the lister engine bed design drawings.As I was looking for some information
on the design of the concrete engine foundation recommended by lister I came across the following in a Lister
publication on the cs series engines:
TITLE:
Lister Instruction Book and Spare Parts List for types 3 1/2-1, 6-1 & 12-2, book103/1053
ON BACK COVER:
printed in England. S.P.5m-1053.
Quote
Foundations
Our standard foundation drawings give the dimensions of suitable concrete beds. These dimensions are
the minimum for a good solid sub-soil and modifications will have to be made where the sub-soil is soft, waterlogged,
or otherwise of a special character.
Set the engine as level as possible, packing under the Engine feet with thin metal strips, placed as close as
possible to the holding down bolts.
Portable Models
Place portable models in as level a position as possible.
Unquote
Noting the last sentence in the quote, it would seem Lister made some CS models that were portable.
In a different manual for the Lister S-O-M
TITLE:
BOOK 312/1052
Instruction Book and Spare Parts List
Lister
A.C.
Start-O-Matic
Electric Generating Plant
On Page 8
Quote
FOUNDATION.
Mount generator set on a concrete block 2' 3" deep including 3" abovefloor level, and 3" wider and longer than the
base plate. When pouring concrete leave four holes 4" square x 15" deep for holding down bolts.
When the concrete block is hard the set should be levelled up and a grouting mixture of cement and sand worked in
under the bearing surfaces of the base plate. The bolts should be grouted in but not tightened down until the grouting
has also set hard.
UNQUOTE
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Were any specs given for the hold-down bolts?
Quinn
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Procrustes
You quote the part of the conversation, which supports your view, while omitting the part below, which does not.
“……As you rightly say technology has moved on and I do not doubt now
that some form of resilent mounting could be used providing good engineering
practices are adhered to….”
The part which "supports my view"? Scott, he admittedly knows nothing about CS engines, much less is he an expert. He tried looking up the answer but didn't get that right, because as Smokey just quoted, the recommendation was a concrete block.
About the technology has moved on, sure it has -- Kubota makes solid engines that are convenient to mount.
I don’t think anyone ever said that a big block of concrete was not a suitable mount. The question was, is it the ONLY suitable mount?
Suitable for what? For the maximum safety and reliability, my money would be on the RA Lister engineer's advice. They are the authority.
The information is accumulating that says it is possible to mount a Lister type engine on resilient mounts. This info is from the opinions of two engineers I spoke with, in addition to the opinion of this person at the Lister Petter company.
Everyone is entitled to his opinion; I give more weight to those from people who are experts in their fields, in this case the engineers and this representative of the Lister Petter company.
The person from Lister didn't pretend to know anything about CS engines, so it's nonsensical to appeal to him as an authority just because he happens to work at that company. The information accumulating about resilient mounts is negligible compared to years of engineering effort, millions of runtime hours and untold failure analyses under RA LIster's belt. The same goes for the advice of two random engineers. Why are you betting on the engine's design, yet weight the advice ot two engineers who don't work closely with Listers higher than the advice of the engine's designers?
Procrustes what exactly would you need to see to convince you that a resiliant mount is acceptable, Just curious?
I respect the authority. If you think they are musty old farts, then you why not take the same view of their engine and get the Kubota instead?
Between the money you paid your engineer, steel, fabrication, resilient mounts, etc you are going to spend a multiple of the $100 that a block would cost you. You'll no doubt end up with something cooler and more portable. I might well do it the same way in your shoes. I continue however to think it ridiculous to hear people say the RA Lister mounting spec is wrong for their own engine. These were gifted, accomplished men who invented the closest thing to a timeless engine there is. Don't you think it's presumptuous to say they're wrong? And if they're old fashioned, why waste your time and money with the engine? No doubt other parts besides the mount are old fashioned too.
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a recommendation from lister for the use of concrete does not constitute the mandatory use of concrete.
has anyone found wording that this has to be used? can you post it? word for word?
words have meaning, and it is very obvious that interpretations can be varied.
we are getting closer, but still not there.
and what about the portable units,, the recommendation is to mount them as close to level as possible,, on what?
if it is portable, do they go on to state that the portable unit has to have a ton of concrete to mount it to when moved to that location?
a portable unit certainly is not portable if it has to be mounted to a ton of concrete at each location?
anyone?
bob g
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I have not encountered a recommendation concerning bolt grade or size, but I have not read the booklet in their entirety either. My Metro came with four 1/2" diameter J- bolts of unknown quality. I will assume the are made of dried peanut butter and replace them with Grade B7 Alloy Steel stud from Mcmaster-Carr. Some have suggested the use of 3/4" diameter studs, I am not sure that the holes in the base lugs on my engine are large enough to accomodate that size.
Did any one else read the papers that I linked to in the other thread? If you did you will see that it is not a "no brainer" with respect to the design of rigid concrete foundations and Lister alludes to this in the quote I posted earlier.
I read "Principles of Foundation Design for Engines and Compressors," by Newcomb and "Don't Gamble on Machinery Foundations" by William Kauffmann. If you tihink you can just pour some concrete into a form of the dimensions recommended by Lister and neglect the underlying soil mechanics, you my end up disappointed. If you have subsoil that is dry gravel, it will tamp down firm you will probably be fine with the Lister design foundation (I am assuming it is the same as the one shown in my Metro owners manual). If you have something more like damp clay you may have some problems inless you increase the foundation bearing area.
Also learned that conventional foundations and resiliant mounted foundations use entirely different design strategies with respect to viibration and natural frequency. With a resiliant mounted system you want the lowest excitation frequency to by at least 3 times greater than the natural frequency of your resiliant mount system. With a conventional foundation you want the natural frequency of the soil to be 2 or more times greater than the excitation frequency. Further, you don't want narrow tall foundations because you could end up with a rocking couple. Also it appears that in 1951 a foundation design rule of thumb was foundation weight about 4 times the machine weight. But please don't take my ramblings as gospel because I don't know squat about soil mechanics. Go read the documents yourself and make up your own mind, as I very well may be wrong on all of this.
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Reading all these posts I see a couple of things I'd like to remark about.
1) "Resilient" mounting is, as y'all use the term, it seems to me, undefined. A damping but flexible modern elastomeric mounting pad, such as we (I'm a millwright) often use mounting large forced-draft fans is pretty forgiving and cheap. Provided the lister type was well balanced I expect that it'd run on pads like those more or less forever. BUT, if the engine became unbalanced while running it might do quite a bit of damage before things came to rest. Therefore I’d think hard about caging those pads. The reason we use these pads has little to do with the machine they support though - instead they're used to isolate one machine from another, and from structures. More on this below. The pads and the concrete are really more similar than you all mostly seem to think…
2) There's a big difference between steel and cast iron. Cast iron is a damping material - really hard to get it to resonate. Steel is much more flexible - depending on the design of an Nth steel weldiment. I’d be very careful about the design of a steel sub-frame, though, imho, there's nothing wrong with a well thought out and rigid one.
3) I decided to mount my 6 - 1 on top of 60 cubic feet of concrete tied into bedrock with epoxy-rebar ties, and topped off with a 160 pound steel plate grouted to the concrete - leveled with a "98" precision level. Why?
Several reasons
It's esthetically pleasing to me - that's important, and it gives the isolation that keeps vibration out of the engine house wall footings.
It’s high enough off the floor that I don’t have to bend or crouch.
The 60 cubic foot slug of concrete derives from Marks Handbook of Engineering (1940 ed) Marks gives the empirical formulas for various types of “gas engines”. (That’s an old fashion term and simply means recips that aren’t steam.) I'll quote from page 1334...
“Foundations. The reciprocating weights of gas engines are greater and the speeds of rotation generally higher than in the case of steam engines, necessitating more mass to the foundation, which should always be carried down to a firm footing. Concrete floors and the walls of the engine house should not be tied rigidly to the foundations, because of the vibration The average volume of material in foundations for the different types of engines may be taken as follows:
For horizontal engines without outboard bearing, 14 to 18 X bhp cu ft.
For horizontal engines with outboard bearing, 19 to 22 X bhp cu ft.
For vertical engines without outboard bearing, 7.7 to 8.8 X bhp cu ft.
For vertical engines with outboard bearing, 9.8 to 10.5 X bhp cu ft.”
The 6-1 is a vertical with outboard bearing, and the arithmetic is obvious. The 6-1 Lister type needs, according to Marks, about 2 yards of concrete or a bit more. But, regardless of this mass – the handbook emphasizes the necessity for isolation. This guide-line is, as should be obvious, for infinite life-cycles and zero cumulative vibration damage to the housing structure.
Marks 1940 seems about right for an "oldtimey" engine. Moden engineering handbooks and foundation formulas are going to let you get away with a lighter foundation, of course, but it that so important?
Looking at the implications of Marks, what seems really important about mounting is 1) that the engine not introduce vibration into adjacent structures, and 2) that the engine is supported firmly so that it can't damage itself. That's consistent with the old Lister instructions, and also consistent with modern damping-vibration pad mounting - if done right.
Peace.
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Smokey,
I read a couple of the papers with interest. I won't pretend to be well versed in the engineering, though I do remember the physics of simple harmonic motion, spring constants, damping, etc. from college nearly 30 years ago.
I wonder what is expected to be the dynamic motion of an engine/generator mounted to a rigid frame, itself coupled to the earth via the resilient mounts that everyone has been talking about. It seems to me that if the mounts are tuned right, the motion of the engine/generator should be very slight, perhaps invisible to the eye. And if that is the case, what is the difference between mounting the contraption on resilient mounts vs. just bolting it to something heavy enough to keep it from rattling?
Quinn
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Quinnf,
I think that if the mounts are engineered properly to the application, that the relatively low mass of the engine/grame/generator system will have relatively high vibration amplitude compared to a similar mounting system that employed much higher mass. G-I has touched on this in his post about designing a steel frame http://listerengine.com/smf/index.php?topic=1097.0.
What I have posted here is not based on personal experience, I am no expert by any means. Its just my understanding of the problem based on what I have read and conversations I have had with people smarter than I. In fact I am at the design stage of the foundation of my Merto 6/1 so I guess you could say that I am a motivated student in this area,
A friend of mine mounted his listeroid genset on rubber mounts. It moves around a bit, there is a both vertical and a horizontal vibration motion component. He is satisfied, I have reservations about what the vibration will do to fuel lines, fuel tank, etc in the long run. To each his own.
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It seems that those who believe that the ONLY way to mount a Lister type engine will continue to believe so no matter what.
Procrutes you said
Why are you betting on the engine's design, yet weight the advice ot two engineers who don't work closely with Listers higher than the advice of the engine's designers?
Well that is not what I am doing. One of the engineers I spoke with works for Lister Petter company, The other’s job is to design systems for stationary engine mounting. The third person I mentioned was the one who responded to the e-mail I sent to the link on their web site and I very clearly pointed out in my post that this was not coming from the engineer I spoke to at Lister Petter.
Pro said
Suitable for what? For the maximum safety and reliability, my money would be on the RA Lister engineer's advice. They are the authority.
I could not agree more, that’s why I contacted them. The engineer I spoke with at Lister Petter said as long as the frame was very rigid a resilient mount would work, he suggested I speak to the people at Ebco http://www.ebco-inc.com .
And before someone tries to negate the opinion of the Lister Petter engineer just because he did not work on the design team for the Lister 6/1 let me quote an often used phrase by another member “….the laws of physics have not changed…..”
I am confident that a good engineer can grasp the forces involved in a Lister engine, they work with this stuff on a daily basis. For the people here, myself included this is complicated, for a trained engineer it is not, its just another design and set of quations . They get the physics and know the math.
These were gifted, accomplished men who invented the closest thing to a timeless engine there is. Don't you think it's presumptuous to say they're wrong? And if they're old fashioned, why waste your time and money with the engine? No doubt other parts besides the mount are old fashioned too.
I don’t recall anyone ever saying the engineers were wrong, to the contrary, they did a great job and a concrete mount works well. I suggest it is presumptuous to dismiss the opinion of 2 engineers one of whom works for Lister just because the original suggested mounting method was concrete. But along with the concrete come an unwelcome side effect, vibration transmission.
What some people miss or confuse is that omission of a mounting method DOES NOT mean exclusion of that method. Lister never mentioned using a block of cast iron the same dimensions as the concrete block, would that not work as well? If Lister said that resilient mounting was not suitable for these engines because of x that would be a different story.
Again I believe a concrete mount will do the job, but I require more than just a solid engine mount, I require reduced vibration and noise transmission to areas outside of the engine room. If I did not require this I would not have looked into alternative mounting options. I think many people would benefit if we as a group came up with options.
Everyone benefits from more choice.
Scott
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Hi
I've been following this thread for a while. It seems to me the engine you want to mount is the first place to start. Some of the poorly made engines are WAY out of balance and some are not. some balance weight is in order
Mine happens to be pretty well balanced and I am running at 650rpm instead of the 1000 it is suposed to develop it's rated horse power.
I put it on a heavy skid because I wanted to be able to pull it on a trailer and move it if I wanted. It does a rather sedate little dance when running. The engine, skid and gen head weighs around 2500lb.
If the engine is to be run in the same place for many years then mount it on concrete. The lump of concrete should weigh double the engine. I think. The bigger the better. If your engine foundation is to be surounded by a concrete floor you should put foam insulation around the engine foundation to keep any movement, viberation from transmitting to the surounding structure.
Just my $.02
Dennis
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Scott:
when you get tired of beating the drum,,, let me know,,, i am resting and waiting :)
i simply cannot believe how narrow minded some folks appear to be
you, i and others while exploring the possibility of useing a resilient mount have never said that concrete is the wrong way to mount a lister
some folks are so selective in what they take from reading a post it leads me to really wonder about the exact wording of the lister original recommendation of using concrete.
to some folks the fact that lister even mentions the word "concrete" makes its use mandatory, let alone the vagaries of a "recommendation"
and i have stated this fact too, and i am glad to see at least one other see the logic
"just because lister makes no mention of resilient mounts does not negate their possible use"
and you are spot on,,, if instead they had stated..
"we do not recommend the use of resilient mounting designs" or "we don't recommend resilient mounting designs, because of..." then yes one would have a bold uphill battle to get support for using them.
before some clever guy comes back with "well they didn't mention resilient mounting schemes because they were not around then" that clearly is not the case, they were in widespread use way before lister built the diesel. or .. "they did not anticipate the need or anyone trying to use them", that dog don't hunt either!
tag me,, tag me... :)
bob g
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I wonder what is expected to be the dynamic motion of an engine/generator mounted to a rigid frame, itself coupled to the earth via the resilient mounts that everyone has been talking about. It seems to me that if the mounts are tuned right, the motion of the engine/generator should be very slight, perhaps invisible to the eye. And if that is the case, what is the difference between mounting the contraption on resilient mounts vs. just bolting it to something heavy enough to keep it from rattling?
Quinn
Aha! I'm glad someone asked. I've been tinkering with the numbers now for about a week. Before everyone rolls their eyes ::), these are only indicative and in the vertical direction only, your mileage may vary blah blah blah.
For me, with my airmounts - I calculate a jiggle of about 1mm above and below the centreline at 650RPM. This is with a few parameters :
- Imbalance forces of about 15kg around a stroke of 138mm - 5kg of that is typical piston mass. The rest is the imbalance due to a 50% bobweight, and I've added a bit more for luck/combustion force, but it really needs to be factored in better.
- A supported mass of 1000kg.
- A spring rate of my airmounts of 13kN/m
This gives me a resonant peak that's at about 70RPM for imbalances, 35RPM for firing pulses, and at 650RPM, total forces transferred to the ground are about 25kg. As the mounts store the energy that isn't transferred to the ground and give it back to the system being supported, the jiggle is increased compared to something that absorbs/transfers that energy onwards like the concrete.
If I plug some silly numbers (for me ;D ) into my spreadsheet for concrete, say 2500kg, spring rate to the subsoil of 100MN/m and keep the rest the same , I get :
A deflection of about 0.05mm up and down, resonant points at 1300/650RPM(Hmm. Better add more concrete!) and at 650RPM, total force transferred to the subsoil of about 500kg. Probably actually a lot more if we did accidentally strike resonance as you're effectively throwing and catching a 2500kg concrete block.
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i simply cannot believe how narrow minded some folks appear to be
you, i and others while exploring the possibility of useing a resilient mount have never said that concrete is the wrong way to mount a lister
Bob, you've laid into folks on this very board for proposing modifications to the 6/1. You pointed out in great detail that such changes aren't known to be right until they've been field tested for hundreds and thousands of hours and the failures have been analyzed. How is what you are doing any different?
It's commendable to explore the use of resilient mounts is commendable and I'll read the results with interest. Speculating whether they're as good as the block is just that, speculation.
some folks are so selective in what they take from reading a post it leads me to really wonder about the exact wording of the lister original recommendation of using concrete.
Smokey posted it earlier in this thread. It plainly says to use a block of at least a particular dimension.
to some folks the fact that lister even mentions the word "concrete" makes its use mandatory, let alone the vagaries of a "recommendation"
I don't know what you mean by 'mandatory', you said that earlier too. It's no more mandatory than that you keep it topped off with oil. Either way you're out of spec and they can void the warranty. It's not a 'recommendation' per se, it's a specification.
and i have stated this fact too, and i am glad to see at least one other see the logic
"just because lister makes no mention of resilient mounts does not negate their possible use"
and you are spot on,,, if instead they had stated..
"we do not recommend the use of resilient mounting designs" or "we don't recommend resilient mounting designs, because of..." then yes one would have a bold uphill battle to get support for using them.
before some clever guy comes back with "well they didn't mention resilient mounting schemes because they were not around then" that clearly is not the case, they were in widespread use way before lister built the diesel. or .. "they did not anticipate the need or anyone trying to use them", that dog don't hunt either!
You're running toward the wrong goal line IMO. Lister knew full well about resilient mounts, yet specified the concrete block. What's the obvious conclusion?
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It seems that those who believe that the ONLY way to mount a Lister type engine will continue to believe so no matter what.
Not so. It's the proven way, and the conclusion of years of engineering, countless failure analyses, and millions of hours of runtime. I'm fine with other mounts, but it's unrealistic to think they will be better.
Procrutes you said
Why are you betting on the engine's design, yet weight the advice ot two engineers who don't work closely with Listers higher than the advice of the engine's designers?
Well that is not what I am doing. One of the engineers I spoke with works for Lister Petter company, The other\u2019s job is to design systems for stationary engine mounting. The third person I mentioned was the one who responded to the e-mail I sent to the link on their web site and I very clearly pointed out in my post that this was not coming from the engineer I spoke to at Lister Petter.
But that's exactly what you are doing: you are favoring a small set of information over the conclusions of years of engineering, countless failure analyses, and millions of hours of runtime embodied in the mounting specification. Just a little while ago you took the word of a clerk who admitted not to know about the old engines to be the word of Moses.
Pro said
Suitable for what? For the maximum safety and reliability, my money would be on the RA Lister engineer's advice. They are the authority.
I could not agree more, that\u2019s why I contacted them. The engineer I spoke with at Lister Petter said as long as the frame was very rigid a resilient mount would work, he suggested I speak to the people at Ebco http://www.ebco-inc.com .
And before someone tries to negate the opinion of the Lister Petter engineer just because he did not work on the design team for the Lister 6/1 let me quote an often used phrase by another member \u201c\u2026.the laws of physics have not changed\u2026..\u201d
I am confident that a good engineer can grasp the forces involved in a Lister engine, they work with this stuff on a daily basis. For the people here, myself included this is complicated, for a trained engineer it is not, its just another design and set of quations . They get the physics and know the math.
You can find an engineer who will mount your engine on haybales, and plenty of ME's helped design the Tacoma Narrows bridge, and the Reliant K. The epitome of research on mounting Listers no doubt occurred during their manufacture, by the same team that designed the engine. You find an engineer who will gladly take your money to build a teleporter or a Heisenberg Compensator (http://seattle.craigslist.org/sno/tls/216699897.html). That doesn't prove anything. Some engineer at Lister is charged with answering customer's questions. Who's to say he knows anything about an engine not made since '81 (?). What particular expertise is this guy guranteed to have? Does he know better than the folks who designed the Lister CS?
These were gifted, accomplished men who invented the closest thing to a timeless engine there is. Don't you think it's presumptuous to say they're wrong? And if they're old fashioned, why waste your time and money with the engine? No doubt other parts besides the mount are old fashioned too.
I don\u2019t recall anyone ever saying the engineers were wrong, to the contrary, they did a great job and a concrete mount works well. I suggest it is presumptuous to dismiss the opinion of 2 engineers one of whom works for Lister just because the original suggested mounting method was concrete. But along with the concrete come an unwelcome side effect, vibration transmission.
On the contrary, it is presumptuous to believe that three professionals who have likely never laid eyes on a CS to know more about mounting it than its designers.
What some people miss or confuse is that omission of a mounting method DOES NOT mean exclusion of that method. Lister never mentioned using a block of cast iron the same dimensions as the concrete block, would that not work as well? If Lister said that resilient mounting was not suitable for these engines because of x that would be a different story.
That's a poor argument. You car specifies that you use gasoline, but doesn't explicitly say not to run it on ketchup.
A metal block may well work, I haven't a clue.
Again I believe a concrete mount will do the job, but I require more than just a solid engine mount, I require reduced vibration and noise transmission to areas outside of the engine room. If I did not require this I would not have looked into alternative mounting options. I think many people would benefit if we as a group came up with options.
Isn't that a different issue? I don't know why you can't reduce vibrations from a block as well as from a frame.
-
Pro:
"Bob, you've laid into folks on this very board for proposing modifications to the 6/1."
i am getting to be an old fart and my memory is as short as something else i have, perhaps you can remind me of my having laid into folks on proposed alterations to their engine, some examples please?
"Speculating whether they're as good as the block is just that, speculation."
you are absolutely right at some level, but good as a block for what purpose?
i have not beat up the use of a block of concrete, and would use one in many instances myself.
i damn sure can speculate that i can get the result i need with the use of resilient mounts as will many folks, any harm in speculation, or working toward that goal?
how far would mankind have gotten if we don't challenge what was done before? how do you further your knowlege of anything if you don't question? how do we know what we are told is the truth if we don't investigate and ask for some level of proof?
" It plainly says to use a block of at least a particular dimension."
oh it does, does it?
" Our standard foundation drawings give the dimensions of suitable concrete beds. These dimensions are
the minimum for a good solid sub-soil and modifications will have to be made where the sub-soil is soft, waterlogged,
or otherwise of a special character."
"These dimensions are the minimum for a good solid sub-soil",
what is good, what is the margin of error? this is subjective and leaves room for interpretation
"modifications will have to be made where the sub-soil is soft, waterlogged,
or otherwise of a special character."
boy that is sure specific as mud, subjective as hell, and no specific details as to how to modify to fit certain conditions, some of which might very well be totally outside the parameters for their suggested specifications, then what?
"Portable Models
Place portable models in as level a position as possible."
what about these portable units? obviously they must have made one or two, did they not warranty those? how did they get around the use of concrete on these? is it not possible that perhaps the portable units were of the upper 10% of the group in being well balanced?
" Lister knew full well about resilient mounts, yet specified the concrete block. What's the obvious conclusion?"
the obvious conclusion can be many
1. they didnt work with the resilient mounts period,
2. they did and found them not to work with average balanced engines
3. they like every other manufacture of engines left it to the end user to work out suitable resilient mounts if they wanted them.
4. etc. put your reason here
obviously there can be no "obvious" conclusion to be drawn.
proofs don't come from "obvious" anything, they come from "facts"
if you have followed this debate closely you will notice that there has been all sorts of assertions
that is what i have a problem with, assertions
it has been asserted that the block of concrete was an intregal part of the original design, i have asked for some documentation to support this claim, to date none have appeared!
it has been asserted that the engineers based the design on moving the center of mass from the engine to within the block of concrete, i have asked for any documentation of this as being fact, even some sort of mention in any book, memoir, anything... to date nothing has
been presented to support this claim!
it has been asserted that the engine will be damage if not mounted to a specific concrete block, again i have asked for some documentation, some mention, some record, newsclip, anything to support this claim, to date nothing!
it has been asserted that the ommission of any word from lister on the use of resilient mounts proves they cannot be used, again some
mention anywhere that supports that they say no dont use them, or any documentation that they tried and failed, how about any mention of anything re. their use or non use?
and on and on.
your side can make assersions, and speculate on why lister spec'd concrete, fair enough
my side therefore can speculate and make assersions, as to the viability of using resilient mounts.
my side of the arguement has not taken a rabid stand against concrete, although the same cannot be said for some members of your camp against the use of resilient mounts.
you dont like 'em fine, don't use them. you dont think they will work then provide some form of reasoning other than the original lister engineers didnt mention their use.
bob g
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Procrustes
I will assume you are an intellectually honest person, as such I ask you the following question:
What proof do you require to acknowledge that it is possible to mount a Lister type engine to something other than a cubic yard of concrete?
Best regards
Scott
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pro:
one question from me
"what proof do you have that lister engineers even tried resilient mounts? or even discussed the possibility of useing them?"
ok i guess that was two questions
bob g
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Procrustes
I will assume you are an intellectually honest person, as such I ask you the following question:
What proof do you require to acknowledge that it is possible to mount a Lister type engine to something other than a cubic yard of concrete?
Best regards
Scott
Of course it's possible, never denied it. I may do so myself.
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pro:
one question from me
"what proof do you have that lister engineers even tried resilient mounts? or even discussed the possibility of useing them?"
ok i guess that was two questions
bob g
That's silly to me, Bob. They'd be incompetent if that were true.
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pro:
slippery aren't we?
that was a double question, not a statement
1. what do you find silly about the question, perhaps i can clarify or simplify it?
2. how would they be incompetent? what kind of answer is that to a question
did you not understand the question?
let me try again
have you any documentation that you could direct me to that makes any mention at all of either
them trying to use resilient mounts, or
even discussed their use?
even one sentence? one faded picture?
hell i would take a statement from one of the engineers gardeners, having overheard some mention of, from the paperboy's girlfriends, uncle twice removed :)
jeesh how much simpler can i make it,,,
somebody show me something that states they even considered the use of resilient mounts... anyone?
any mention at all, for or against their use? anything?
and you are asking me to conclude that they cannot be used! because there is no mention anywhere one way or the other.
please,,,, be serious
who is calling who an idiot?
you must think me a fool to accept in the absence of any mention, let alone proof that the resilient mounts are a bad thing?
talk about jumping to conclusions!
bob g
-
Pro:
"Bob, you've laid into folks on this very board for proposing modifications to the 6/1."
i am getting to be an old fart and my memory is as short as something else i have, perhaps you can remind me of my having laid into folks on proposed alterations to their engine, some examples please?
Forgive me for being lazy. It might have been hydraulic lifters and turbos. You spoke eloquently about how the proof of design was the success of the design. I believe Kyradawg bore the brunt of it. Probably I paraphrased you out of recognition.
"Speculating whether they're as good as the block is just that, speculation."
you are absolutely right at some level, but good as a block for what purpose?
i have not beat up the use of a block of concrete, and would use one in many instances myself.
With the caveat 'for what purpose?' we are probably in agreement. I've said in this thread that for most of us pretty much any mount would be fine. Listers were designed to be run for tens of thousands of hours, a requirement very few of us have. I continue to believe though that for the long haul and safety, the smart money is on the block.
i damn sure can speculate that i can get the result i need with the use of resilient mounts as will many folks, any harm in speculation, or working toward that goal?
As I said, it's commendable.
how far would mankind have gotten if we don't challenge what was done before? how do you further your knowlege of anything if you don't question? how do we know what we are told is the truth if we don't investigate and ask for some level of proof?
By all means do challenge and investigate. I'll read your results with interest. My sole point is that it's presumptuous for one to say that one knows better than RA Lister how to mount a Lister.
" It plainly says to use a block of at least a particular dimension."
oh it does, does it?
" Our standard foundation drawings give the dimensions of suitable concrete beds. These dimensions are
the minimum for a good solid sub-soil and modifications will have to be made where the sub-soil is soft, waterlogged,
or otherwise of a special character."
"These dimensions are the minimum for a good solid sub-soil",
what is good, what is the margin of error? this is subjective and leaves room for interpretation
"modifications will have to be made where the sub-soil is soft, waterlogged,
or otherwise of a special character."
boy that is sure specific as mud, subjective as hell, and no specific details as to how to modify to fit certain conditions, some of which might very well be totally outside the parameters for their suggested specifications, then what?
That's a nit. All that says is that the standard size block will be inadequate in some situations. Presumably Lister would make site-specific recommendation. I don't know.
You left out the specification for a normal block, which is complete.
"Portable Models
Place portable models in as level a position as possible."
what about these portable units? obviously they must have made one or two, did they not warranty those? how did they get around the use of concrete on these? is it not possible that perhaps the portable units were of the upper 10% of the group in being well balanced?
You've got me there. I know nothing at all about portables.
" Lister knew full well about resilient mounts, yet specified the concrete block. What's the obvious conclusion?"
the obvious conclusion can be many
1. they didnt work with the resilient mounts period,
2. they did and found them not to work with average balanced engines
3. they like every other manufacture of engines left it to the end user to work out suitable resilient mounts if they wanted them.
4. etc. put your reason here
obviously there can be no "obvious" conclusion to be drawn.
proofs don't come from "obvious" anything, they come from "facts"
We will have to agree to disagree here. I say RA Lister was incompetent if they neglected to consider resilients, or they secretly approved of resilients but didn't want to tell anyone, etc. Maybe as you say the block is CYA for poor balance. Or maybe you know better than they.
if you have followed this debate closely you will notice that there has been all sorts of assertions
that is what i have a problem with, assertions
I've deleted the assertions I did not personally make.
it has been asserted that the block of concrete was an intregal part of the original design, i have asked for some documentation to support this claim, to date none have appeared!
I don't have that. I don't have documentation for a lot of things that I believe. My argument is basically an appeal to authority: I respect the design, so I respect the designer's mounting recommendation.
it has been asserted that the ommission of any word from lister on the use of resilient mounts proves they cannot be used, again some mention anywhere that supports that they say no dont use them, or any documentation that they tried and failed, how about any mention of anything re. their use or non use?
I didn't say they can't be used. Simply stated, my argument is that if you want to mount it the best possible way, your best bet is to follow the spec. Perhaps we're arguing about nothing.
your side can make assersions, and speculate on why lister spec'd concrete, fair enough
my side therefore can speculate and make assersions, as to the viability of using resilient mounts.
my side of the arguement has not taken a rabid stand against concrete, although the same cannot be said for some members of your camp against the use of resilient mounts.
you dont like 'em fine, don't use them. you dont think they will work then provide some form of reasoning other than the original lister engineers didnt mention their use.
I don't disagree with any of this. My only caveat is that I'd bet resilient mounts don't bid fair to work as well. For an engine designed for tens of thousands of hours, this won't make a difference in most modern situations.
On second thought I disagree with your characterization of my argument. It's not that the original engineers didn't mention their use, it's that they specifically, unequivocally say concrete. You could make your same argument, they didn't mention marshmallow mounts, therefore they don't recommend against the use of marshmallows. It doesn't hold water.
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pro:
slippery aren't we?
that was a double question, not a statement
1. what do you find silly about the question, perhaps i can clarify or simplify it?
2. how would they be incompetent? what kind of answer is that to a question
did you not understand the question?
let me try again
have you any documentation that you could direct me to that makes any mention at all of either
them trying to use resilient mounts, or
even discussed their use?
even one sentence? one faded picture?
hell i would take a statement from one of the engineers gardeners, having overheard some mention of, from the paperboy's girlfriends, uncle twice removed :)
jeesh how much simpler can i make it,,,
somebody show me something that states they even considered the use of resilient mounts... anyone?
any mention at all, for or against their use? anything?
and you are asking me to conclude that they cannot be used! because there is no mention anywhere one way or the other.
please,,,, be serious
No, Bob, I do not have documentation or a photo of Lister engineers experimenting with resilient mounts. I don't feel the need for any. I trust in the competence of their engineers. They designed a wonderful engine. I don't see how this buys you anything.
who is calling who an idiot?
Certainly not me. I said your argument is silly. I apologize if that hurts your feelings. I don't think you're an idiot.
you must think me a fool to accept in the absence of any mention, let alone proof that the resilient mounts are a bad thing?
talk about jumping to conclusions!
bob g
But I never said they're a bad thing. Read my last post. I don't think you're a fool, but I don't get what you're after here.
-
pro:
perhaps we are coming to an understanding of each other here.
i dont recall taking a stand against the use of hyd lifters or turbo's
although i think it might be very difficult to impliment and there may be longevity issues as well
still wondering what part of my arguement you find to be silly?
your comment about them not mentioning marshmellows as mounts not precluding their use is not apples to apples at all
no one to my knowlege ever, either contemplated or used marshmellow for anything other than eating or possibly decoration.
whereas resilient mounts were in widespread use at the time and every since.
it could be argued that with resilient mounts being commonplace during the time of design of the engine, they might have mentioned not using them if they were against there use. Certainly they might have considered the possibility that someone might want to use them, and warn against their use in some way if they were detrimental to the engine. wouldnt you think?
they had to consider that perhaps someone might try to use them, therefore warn against their use if it might damage their engine, seems logical to me.
what seems most logical to me is, they knew they could be used but they did not want to get into specific applications and having to engineer for hundreds of applications, so they just didnt mention them.
i wonder if it is possible there is a lister engineer that worked with these engines and their applications that is still alive, now that would be a real coup to locate him.
they ceased production in 81? hmmmm 25 years ago,, maybe there was a 65 yo dude working in the engineering capacity for 40 years still alive,,, he would be 90 years old now... pushin it huh?
lets go find him! all we need is one!
i think i will place a call to lister monday and see if any of the old guys there know of such a guy in an old folks home somewhere in england.
bob g
-
pro:
perhaps we are coming to an understanding of each other here.
i dont recall taking a stand against the use of hyd lifters or turbo's
although i think it might be very difficult to impliment and there may be longevity issues as well
Must have been some other modification. I can't remember either, but I do remember your posts there very well. I wish I could think what to search on.
still wondering what part of my arguement you find to be silly?
I don't attach any importance to the manual not mentioning resilients. The manual is the spec for what you need to do to maintain your warranty. The way not to mount it according to the manual is, anything that's not a concrete block.
Further, you yourself said the resilients were common back then. How could they have neglected to consider them? This is a world class piece of engineering we are talking about. Quite an oversite.
your comment about them not mentioning marshmellows as mounts not precluding their use is not apples to apples at all
no one to my knowlege ever, either contemplated or used marshmellow for anything other than eating or possibly decoration.
whereas resilient mounts were in widespread use at the time and every since.
it could be argued that with resilient mounts being commonplace during the time of design of the engine, they might have mentioned not using them if they were against there use. Certainly they might have considered the possibility that someone might want to use them, and warn against their use in some way if they were detrimental to the engine. wouldnt you think?
Not really. If you deviate from the spec, you void your warranty and you are no longer a concern to them.
they had to consider that perhaps someone might try to use them, therefore warn against their use if it might damage their engine, seems logical to me.
what seems most logical to me is, they knew they could be used but they did not want to get into specific applications and having to engineer for hundreds of applications, so they just didnt mention them.
I won't say it's impossible.
i wonder if it is possible there is a lister engineer that worked with these engines and their applications that is still alive, now that would be a real coup to locate him.
they ceased production in 81? hmmmm 25 years ago,, maybe there was a 65 yo dude working in the engineering capacity for 40 years still alive,,, he would be 90 years old now... pushin it huh?
lets go find him! all we need is one!
i think i will place a call to lister monday and see if any of the old guys there know of such a guy in an old folks home somewhere in england.
Let me know if you find him. I get paid hourly and this debate is going to put me in the poor house.
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Good Grief everyone.
Let me condense 4 pages of argument to two glib sentences:
- We've got people on one side defending the status quo, with no real evidence other than it's the status quo.
- The opposing camp says that just because it's the status quo, doesn't mean that it's the be-all and end-all, and alternatives should be explored.
Whether the performance, cost and complexity of resilient mounts will make them a viable alternative to a concrete mount is - at present - a very subjective thing. I hate subjectivity - it leads to arguments , such as this thread. I want numbers, dammit!
In an engineering scale, this is hardly the Apollo Project here. Much bigger and badder problems have been solved and I have no doubt that a general design of a resilient mount will be sorted out that will combine relative longevity and portability with low levels of vibration transmitted to the surroundings. Of course we will never know for sure until we have many thousands of hours on those mounts, with (for the most part) simple indian clones that have their own quality issues to help muddy the picture.
So lets all just take a little step back and stop going around in circles.
Let people build some mounts (using valid resilient mount design principles), run their engines and report back. If half of them end up with shredded engines after a thousand hours, then I'll be asking some serious questions about their design of their mounts. Not resilient mounts in general, just their particular design. If they're all wildly different designs and they suffer catastrophic failures and I can't pick a common design issue throughout the lot of them apart from just the resilient mount, then - and only then - will I begin to question the validity of a resilient mount in general.
Anyway, on with the debate?
-
This is real easy, except people don't want it to be.
Lister said concrete block, nothing else, during the entire production run of the CS from 29 to 81.
Lister made lots of other engines and did lots of other engineering, the CS was only a small part of their output.
Many if not most of the other engines they made were shipped with flexible mounts specified, ergo Listers, surprise surprise, knew all about resilient mounts, but still never said they were permitted or recommended on a CS
The CS was notable for many things, not just a long production run, but unlike much of the rest of their production, the CS series was designed to basically run forever and never wear out.
If you take an low and reasonable average hours of a CS at 50k and production of 250k units then by the time Lister were printing the installation instructions in the 80's they had about 12.5 million installed hours experience at a very conservative estimate.
It is a STATIONARY engine, if you wanted a portable, semi portable, marine, traction or other engine they would steer you towards a different model in the range.
==================================
As I have stated elsewhere, I was working for someone who needed to see if a lister could be driving a hydraulic pump on 24/7 duty on flexible mounts on a barge, solid mounts would have made her thrum like a rail, so we can experiements with proper strain gauges and proper data capture under a wide range of loads and conditions (with the caveat they were all run on a good engine with no malfunctions) (don't forget the sump design, a barge was ok because it was flat and negligible wave motion) and as I said I can't recall the numbers exactly but as expected there was an amplitude of over a ton on the mounting bolts, which is why Lister used 3/4 bolts eh.
As I have stated else where, been doing engineering all my life, and when you are talking about complex systems, and technically speaking a DIY steel frame and randomly selected mounts that deteriorate with age and varying load conditions etc etc is a very complex system, and complex systems cannot be modelled economically until the capital investment is measured in the tens of millions of dollars, and finite element modelling is not only expensive, it is anything but fast, quicker to built a test bed (which many of you will do) and add strain gauges and capture data (which none of you will do)
RSJ and other extruded steel forms were about when lister was making steel bases for CS series, but they never used them, they welded up honeycomb base structures with very large amounts of deposited weld and very long welds, with a very high proportion of welds (in the honeycomb base) wrapping around an edge of plate, which just about triples the weld strength.
Listers were a short days journey by horse from where cast iron as an engineering material was basically invented, they knew all about its properties and how it differed from steel.
If Listers did not do something, they had a reason, and the reason is usually easy enough to percieve, unless you have an agenda.
========================
None of this says it is an engineering impossiblity to mount a CS on flexible mounts and not detract in any way from the performance of the engine when mounted on a concrete block.
Unless you have a "Standard" (with a capital S) steel frame then every last one is bespoke, and needs to be treated afresh, ditto specification of mounts and mount points etc
This is not a trivial engineering task, doing it is easy, doing it WELL will be vastly time consuming and expensive, and the same end results can be achieved more rapidly in other means. Fools rush in where angels fear to tread.
I'm a time served engineer, I grew up around CS and probably have 100k hours of being "around" them on a daily basis, I grok computers, data aquisition hardware and software, FEMS, and I live in a place where just about anything engineering I want is at worst a phone call away, and I would shy away from a DIY skid frame and resilient mounts, they are a direct analogy to the railway sleeper and cast iron trolley I bought mine on, ok for a few hours here and there in a field not under full load.
Not because I couldn't do a good job of work of it, but because life is too short to spend 400 hours achieving something that can be achieved in 8 by other methods.
========================
The vast majority of you don't even have listers, you have one of a variety of knock off cheapo copies, and by definition you do not know what corners were cut or what effects they have, long or short term.
The best way I can characterise the approch that I see here is many of you appear to think you are starring in your very own episode of mythbusters, can I rubber mount my listeroid so I can stand next to it and feel no vibes?
Yeah you can, provided you are honest, and speak aloud the subject, it only has to work long enough to film the episode and bust the "myth" because by definition you are moving the goalposts and most certainly do not want to play the 100k hours of reliable running scenario.
There are two camps here, and the ones like Mr Belk who isn't playing and needs that shit to work else it is back to stone age survival techniques with tallow candles for light and so on are quite happy to take lister word on the product they made and know better than anyone else. And then there is the other camp, and quite honestly given what many of them appear to want to do if I was an engine salesman I would NOT have steered them anywhere near a lister.
You can, technically, rubber mount a CS PROPERLY, but by definition if you have the ability you would know enough not to try, just like you can, technically, wire a house with live cable, but a coded sparky wouldn't do it (lightly, though he will have a take to tell)
Bob is playing devils advocate and looking for answers that way, they won't come at zero cost and over the internet, catch a flight over here and I can introduce him to people and let the dog see the rabbit.
To give an analogy.
Birmingham (the one here in the UK) was at one time the world centre for small arms production, amongst other things they made 2 shilling muskets for trade, pop a match in the flash hole, stand upright, fill with water and leave overnight, if it didn't weep they were sold.
This got them such a bad name the better gunsmiths of brimingham went to parliament and got a law passed and built their own barrel proofing house (it is still in use today as a matter of fact) which got them their good name back and differentiated them from the trade musket makers.
Mr Belk I am sure will either know this story, or know his subject well enough to accept it and give half a dozen other examples.
Doo wah diddy with his copy of the anarchists cookbok and instructions on how to make a zip gun will say it is all bollocks, just as the naysayers do here, and come up with pressure calculations and flame speeds etc etc to prove they are right, it can be done their way.
Well, it can, by the likes of Mr Belk, but not by them.
end
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Hi I know lister made marine engines very similar to the cs engine! most had a single flywheel.
Don't tell me they poured a big lump of concrete in the boat.
Dennis
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GF-- Good analogy on the guns. English gunmakers are divided into two very distinct 'tiers'. B'ham makers are 'less' that London's because of a bad reputation two hundred years old!!
Eibar Spain is a modern example of "Indian QC" in the firearms trade. :P
Speaking of Eibar...who has tried to assemble a CVA muzzle loader kit? For many years they sold the out of spec and non-fitting parts as "kits". No telling how many prospective gunmakers were ruined by frustration by them. :P
Dkw-- I asked the same questions of the nautical guys months ago. My understanding is that a ships engine mounts are rigid but insulated from the hull. I think the first reference I heard of 'the mount being a part of the rigidity of the crankcase..' was in reference to the diesels used in diesel-electric submarines.
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It seems to me that as Lister describes their primary recommended mounting, the concrete block IS resilient in the sense that it floats in soil isolated from other structures – free to tremble along. The main function seems to be to isolate the engine, and secondarily to locate the engine – both quite vital. True, concrete is not itself particularly resilient, but the soil is. That was my point in saying (above) that the modern elastic pad mount approach and the classical Lister concrete approach are quite similar in effect. Perhaps I did not make that view clear enough. Perhaps the ideal method would be to cast a nice fat concrete block and nest that in a steel frame supported by elastic “resilient” pads, and mount the engine to that. Seems like beating a dead horse, though….which is mostly what one might suspect is going on, ‘course that couldn’t be…
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This is my question phaedrus -
If a concrete mount and a resilient mount are basically the two extremes of the same thing - which they are, generally speaking -
Then why can't I build a reasonably stiff, resiliently mounted frame to mount those 4 engine points to? That is, trade less overall mass for more motion of engine and frame, which is then isolated from the surroundings by more resiliency?
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Guy-Incog.,
[edit: this refers to reply #40 - things are moving fast here]
You said, "A deflection of about 0.05mm up and down, resonant points at 1300/650RPM(Hmm. Better add more concrete!) and at 650RPM," etc.
So if the vertical deflection is 0.05 mm at resonance, what is it when the resonant frequency is moved some odd fraction or multiple of 650 rpm? I bet it is less than 0.05 mm.
What says your spreadsheet?
Quinn
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Quinnf,
It's hard to tell without really pinning down some numbers. Those numbers I picked were quite random and it was only chance that I ended up (and realised while typing) that there was a resonance for the power pulses at that particular point.
The thing is, the concrete block is very well-damped, so resonance peaks are muted as well. But because it's well-damped, vibration forces are easily transferred past the springy subsoil. A few PDFs that smokey posted in the frame thread had quite a lot of detail in it about building a mount to go in differing types of subsoil and their natural frequencies with the loading from the concrete.
Just went to google and found that ASME paper here:
http://www.slideruleera.net/FoundationsForCompressors.pdf
In looking for that one I found 2 more that are related
"Don't Gamble on Machinery Foundations" by William Kauffmann, 2 pages - 1973
http://www.slideruleera.net/MachineryFoundations.pdf
"Basic Vibration & Vibration Isolation Theory" by Unisor Machinery Installation Systems, 11 pages - mid 1980s
http://www.slideruleera.net/BasicVibrationTheory.pdf
Quite interesting reading there , actually.
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OK Guy Ico, long reply, sri. (ref reply # 58)
That seems to me to be a Good Question. It is probably a matter of extent, of degree, more than anything else. If I were to undertake to do that (make a resilient mount) I’d want to start with a well-balanced engine, then I would be concerned with several aspects (I have seen too many screw-ups to be other than cautious).
First: The job has got to be safe. The increased motion of the engine (that you cite) would, I expect, introduce a new and unknown but larger pattern and amplitude of vibration in the engine structure(s). These engines are pretty stiff, so that might well be dangerous.
In particular I would worry about cast iron structures in dynamic tension (such as flywheels) being subjected to tensile transients that might exceed safe limits - in other words this possibility alone would be very serious and discourage me from the trial. Cast iron is marvelous stuff, but when it lets go in a flywheel it can kill – I have seen this and believe me it is not just theory – it is bloody, expensive, and conflict-producing (like legal and otherwise) Iron flywheels (and pieces) can go through concrete walls. Nevertheless I might explore damping elastic pad mounts – you can call these “resilient”, but they, the ones we use in industrial application, are specifically designed to damp vibration. A good industrial supply catalogue will have some guidelines. In any event I would consider the possibility of the engine becoming unbalanced while on such pads – it could then cause great damage. Therefore any such mounting ought to have the pads “caged” and also have vibration sensing emergency trip shutdown provisions. This is common in industry, but it costs money and adds complexity. A trade-off.
Second: transients in the crank web introduced by increased engine motion might well create a cycle-to-failure period replacing the infinite life design of the crank. One would not know if they had created such a “clock” until the “bell rang”, e.g. the crank snapped. This “clock” might tick for thousands of hours. Think of the dynamic motion of the crank as designed, and then add the mass of those wheels bouncing…flexing the web. Might do some bearing damage too, and the two aspects might interact… I understand (but am not certain) that Lister cranks are forged steel – if so you’ve got a spinning (with transient torsions from the piston already) bar-bell on a stiff steel spring, do you really want to bounce it? I’d want to keep that business as simple and quiet as possible.
Third: Based on experience with diesels I assure you that what appear to be trivial matters – using a brass fitting rather than a steel one in, for example, a oil pressure sensing tube, can (and this has happened to me) create a time-to-failure booby-trap. Once I set myself up this way for nearly 100 GM truck diesels to lose oil pressure, each at almost the exact same hours – the disaster took something like a year to present itself…very embarrassing. The point is that any deviation from tried and true practice might, (it’s really impractical to predict); result in a “casualty”, as people in the power-generation racket like to put it. In the case of a Lister type I’d worry about fuel leaks, broken brackets, oil leaks, and sump-sloshing causing the engine to either under or over lubricate. I’d worry about the governor linkages… And, in particular, I’d want to consider what would happen if the engine locked-up… Would it then roll right over in the (or on the) mounts? I have seen a 900 MW steam turbine rotor fail suddenly and transfer a large portion of its kinetic energy to the case. It cracked the case, 9 inch thick steel, for something like 20 feet. Almost rolled right off the top of the turbine building…
All told, I would undertake to mount a Lister type with modern damping elastic pads only in a most conservative and cautious way. I’d like to take measurements of the vibration patters of properly mounted (on concrete) engines of the same type and then examine those patterns on a “portable” mount (something like a Lister bolted to a plate bolted to railroad sleepers set in sand), – using an oscilloscope and any tools, (like a vibration meter from coleparmer) I could get my hands on to define the situation better. (That comparison ought to imply something about acceptable ranges.) I would ballast the engine base as heavily as is practicable (probably with a mix of concrete and scrap) and then work toward finding mounting pads that resulted in a pattern and amplitude of vibration that was as close to the factory design(s) as I could get. I’d cage the pads. I’d add a vibration trip emergency shutdown system, smoke alarm, over speed trip – all the bells and whistles. Then I’d cross my fingers and keep a close eye on things. I am sure it can be safely and properly done, but I am also sure that it must be done right. It’s not a casual undertaking.
Of course, an experiment to see what happens is always useful, and given plenty of time and money I guess it’d be interesting to see just how loose a mounting set up can be and still run without trouble for, say, 50,000 hours. We might all be surprised and pleased to find that the Lister type is so forgiving that it matters little. I suppose we shall just have to wait and see...people are mounting 'em pretty freely. Best, Phaedrus
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Hi
Cageing the mounts sounds good. I seem to remember some Chevy motor mounts would go bad after a lot of years and oil on the rubber, would let go and the tourque would roll the engine to the right and bind the throttle at full.
You had to be on the ball and shut the engine off before you got into trouble.
Dennis
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phaedrus,
All good points to consider. Caging or otherwise restricting mount movement is always a good idea. In the design I'm looking at with airmounts, they'll be set to "fly" just above the normal range of jiggle. Any movement outside the normal range of motion will be caught with a fair-sized bump stop. All the misc parts that are able to be restricted will be - the injector lines and fuel lines are a good example of things that will have a few more restraints of them.
For flexing of crankshafts,etc ... this is a point that I have difficulty grasping. Someone point out to me where I've gone wrong with the following example:
Say we have a crankshaft, and a flywheel on the end of it and the whole shebang's rotating. It's imbalanced somehow, by forces acting on it, by a weight being in the wrong spot on the flywheel or crankshaft,whatever. There's no bearings getting in the way, it's just a crankshaft and flywheel spinning by itself.
The whole thing will want to rotate about it's centre of mass (or apparent centre of mass if a force is acting on it). If it can freely rotate about it's centre of mass, the net bending force on the flywheel and crankshaft will be zero and nothing will flex. Basically, the centreline of the crankshaft/flywheel will go around the centre of mass in a small circle.
If I restrict it's movement a little bit, say with a bearing that's mounted to a resilient mount, then the system cannot freely rotate around the centre of mass and the force generated is proportional to the angular velocity squared and the distance of the shaft from the centre of mass. The force is essentially dependant on how flexy the mount is - if the mount allows the bearing (and thus, the shaft) to move towards the centre of mass a little bit, then the less force is applied.
If I now restrict the shaft with a rigid bearing between the flywheel and imbalance, the distance between the centre of mass and the centre of rotation is now at a maximum and thus the forces are at a maximum. Basically the fixed bearing acts as a pivot for the imbalance forces to lever against.
Can anyone help me out here? It's really starting to bug me. :D
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seems reasonable to me,,, but then again i just woke up :)
perhaps someone will analize each of your examples and give a well reasoned answer has to why you are wrong.
i for one would like to sit down and listen to that reasoning
so whoever takes it upon himself to explain this, please try and do a complete job of it, and not just pick around the edges.
bob g
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I'm with Mobile Bob....I'm receptive to a complete explaination.
Guy Inc. brings up some good points, but I have trouble with the 'rotating around it's mass'.....or more likely, I don't have the theoretical part of that ingrained enough to understand it.
In *my* head I can see the crankshaft and flywheels spinning 'in space, without bearings' as ONLY happening with perfect balance.
My experiment at about ten years old of making an aluminum spinning 'top' and then drilling a small hole in one side to better hold the starting string that ruined it's ability to spin convinced me of that a long time ago.
My *observation* with my engine has been-- If given ANY room to move around, that space will gradually increase until there is a point of failure somewhere in the hold-down system.
With TRBs big enough for a dump truck and a crankshaft bigger than a V-8 and cast iron doesn't flex all that much...where is the movement EXCEPT for the movement of the entire engine in reference to the world? If we stop THAT movement and tie the engine TO the world, aren't we then using the power generated by the engine for benificial work instead of losing some to 'vibration'?
I have a Mini-Petter pumpset that produces a pound more pressure with the (solid concrete) mounting bolts tightened than when slightly loose (from shrinkage of the 6 x 6 wood 'pad') between engine and concrete. Is it because the engine is 'stronger' or is it because of turbulence caused by vibration in the pumping part?
If all the movement is confined to the rotating mass and the reciprocating piston AND the design of the (extremely) large parts are to prevent any internal flexing or movement from the forces encountered, there is no effective stress to adjacent parts....as long as everything is stable. Stress applied without movement has no energy, right?
Now that MY confusion is added to the rest, I feel better. ;)
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For flexing of crankshafts,etc ... this is a point that I have difficulty grasping. Someone point out to me where I've gone wrong with the following example:
Say we have a crankshaft, and a flywheel on the end of it and the whole shebang's rotating. It's imbalanced somehow, by forces acting on it, by a weight being in the wrong spot on the flywheel or crankshaft,whatever. There's no bearings getting in the way, it's just a crankshaft and flywheel spinning by itself.
The whole thing will want to rotate about it's centre of mass (or apparent centre of mass if a force is acting on it). If it can freely rotate about it's centre of mass, the net bending force on the flywheel and crankshaft will be zero and nothing will flex. Basically, the centreline of the crankshaft/flywheel will go around the centre of mass in a small circle.
You say you have a degree in physics, yet you appear to have forgotten such basics and modulus of elasticity.
Metal bends and twists under torque, it has to, and if it bends and twists then all by itself it is imposing precsessive 9as in gyroscopic precession) forces upon itself, so it is undergoing cyclic fatugue.
I have repeatedly asked you and other to do the maths, nobody will.
Why do you think early spoked flywheels were spiral spoked, yes the material was not as good as later cast, but by definition unless the entire flywheel was NOT accelerating and decellerating with each stroke as a theoretical solid disk with no elasticity, but WAS twisting radially with the torque, spiral spokes would not have been necessary.
Better materials didn't mean those forces disappeared, it just meant they were eclipsed by improving youngs modulus shear etc etc etc
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Ah, Guy_F - sometimes the simplest things(?) elude me.
I am aware of young's modulus. You don't need it often when you majored in optics unfortunately. Neither do you have to understand crankshaft flex in a 90-year old engine design that's being mounted in such a fashion that there is no 'fixed' point in it.
The old adage is, "on the internet, no-one knows you're a dog". So until someone can give me a hard answer, with numbers and pretty vector diagrams (preferably) so that I can follow the same steps and reach the same conclusion, all claims of "it's perfectly obvious" are moot. If it's obvious, one should be able to explain it in a few lines of text. So is it?
With the brief clarity of a cup of tea this morning, what I am thinking is that, say, with a rigid bearing between flywheel and crankshaft, any forces on either end will have a bending moment around the immobile bearing. Allow that bearing to move in the direction of the force a little and the forces at the other end of the now moveable pivot are altered. Everything still flexes, just where and how much is the question here, is it not?
Can you do the math Guy_F? I've posted this question about crankshaft forces before up in the thread and I'll throw it out to the crowd again. Can anyone explain fully?
If you can, then set it out and let us (well, me) know once and for all. If you can't .... then at least we've still got heated words to back up our arguments,eh?
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hey, i am no engineer,,, and i am still waiting :)
i understand physic's, and am fair with computing and modeling
so i think i can follow along with the explanation.
i also understand what i have seen in the field, engines that are rigidly mounted to a subframe, that are meant to be
a moveable stationary engine (such as oil field mud pumps) break crankshafts quite easily if dropped a very few inches from the truck that is placing them ( i might add on the ground not concrete). whereas
the same engine mounted resiliently in a truck can sustain being dropped the same distance without breaking the crank.
no granted neither engine was running when the cranks broke and as such the failure was from shock loading. but the principle seems to be the same. just happens much quicker instead of over time.
come on somebody educate me
bob g
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Ah, Guy_F - sometimes the simplest things(?) elude me.
I am aware of young's modulus. You don't need it often when you majored in optics unfortunately. Neither do you have to understand crankshaft flex in a 90-year old engine design that's being mounted in such a fashion that there is no 'fixed' point in it.
The old adage is, "on the internet, no-one knows you're a dog". So until someone can give me a hard answer, with numbers and pretty vector diagrams (preferably) so that I can follow the same steps and reach the same conclusion, all claims of "it's perfectly obvious" are moot. If it's obvious, one should be able to explain it in a few lines of text. So is it?
With the brief clarity of a cup of tea this morning, what I am thinking is that, say, with a rigid bearing between flywheel and crankshaft, any forces on either end will have a bending moment around the immobile bearing. Allow that bearing to move in the direction of the force a little and the forces at the other end of the now moveable pivot are altered. Everything still flexes, just where and how much is the question here, is it not?,
Can you do the math Guy_F? I've posted this question about crankshaft forces before up in the thread and I'll throw it out to the crowd again. Can anyone explain fully?
If you can, then set it out and let us (well, me) know once and for all. If you can't .... then at least we've still got heated words to back up our arguments,eh?
Funny how you can get a degree in optics and never encounter a lens being deformed by the shock loading of transmission of laser pulses. Youngs is the rate of change of stress with strain, and in optics is VERY commonly used as the operating principle of polariscopes, polarimiters, etc.
It's not even my field, but I know this. Strange.
Can I do the math (for an engine), you ask. Yes I can.
I've just spent about 3 hours tonight lecturing a (very promising) student.
People come in two flavours, those that prefer to be able to ask a question and get an answer, and those that prefer to to learn. The latter are in the minority.
The easy way to differentiate between them are the book learners and the thinkers. Book learners are always quick to do things like reach for spreadsheets and start banging made up (as opposed to tabulated from instruments over time) numbers into the first formula they found that appears to fit the bill.
Thinkers know everything that ever was and ever will be is subject to change, and sometimes some of those changes will be unexpected. A book learner will tell you he has calculated that slings and chains and load gives a safety factor of seven, a thinker will still arrange things so there is a safety sling and make sure nobody is standing in the path of anything, including the slings. A friend of mine lost his head, literally, when a hawser with a safety factor of about six parted, three other were hospitalised with serious injuries, the only one who walked away unscathed was a thinker, a canadian logger, who ducked for the cover he made damn sure he was standing next to the instant he saw the moisture being wrung out of the hawser.
Of course, if the book learners had KNOWN that the magnetic resonance (hall effect) testing of the wire rope was giving erroneous results because nobody included the effects of the big welder on the instrument head they might have calculated a different safety factor, and if the book learners had bothered to figure the rapid temperature rise from frozen on the drum to being played out under full tension they might have lowered it a bit more, and if the book learners had known that they had used the wrong equation (or rather, left out two important ones from the over all calculation) they might have lowered it a bit more.
Inquests suck. Misadventure my ass.
That wasn't the first, or the last, time in my life I have said out loud to other people "These assholes are going to kill someone one day" and lived to be proven right, me, I'm too small to stop it, I shouted, I've blown whistles, I've threatened to quit, I've quit, it never makes any difference because the one thing that is never in short supply is some asshole with book learning who is ready to sign off on it.
I've had pressure, deadlines and downtime and seriously big bucks for every hour that shit wasn't up, but money and metal can always be replaced, kill someone and you have had all they ever were and ever will be and nothing you ever do will dent that.
Only difference big bucks at stake makes is there is enough in the kitty for blone bints with big tits and an open bat tab to schmooze the PR machine when it all goes wrong.
You got a spreadsheet for taking a mans hand off so he never works again? What does that work out at in dollars?
I know you got fancy tables for risk assesment, that's what they are called anyway, but the purpose isn't to mitigate risk, it is to wash your hands when the numbers come up, hey, we did a risk assessment, so we ain't culpable.
Kipling said "when arf your bullets fly wide in the ditch", things ain't changed
The Young British Soldier
When the 'arf-made recruity goes out to the East
'E acts like a babe an' 'e drinks like a beast,
An' 'e wonders because 'e is frequent deceased
Ere 'e's fit for to serve as a soldier.
Serve, serve, serve as a soldier,
Serve, serve, serve as a soldier,
Serve, serve, serve as a soldier,
So-oldier OF the Queen!
Now all you recruities what's drafted to-day,
You shut up your rag-box an' 'ark to my lay,
An' I'll sing you a soldier as far as I may:
A soldier what's fit for a soldier.
Fit, fit, fit for a soldier . . .
First mind you steer clear o' the grog-sellers' huts,
For they sell you Fixed Bay'nets that rots out your guts --
Ay, drink that 'ud eat the live steel from your butts --
An' it's bad for the young British soldier.
Bad, bad, bad for the soldier . . .
When the cholera comes -- as it will past a doubt --
Keep out of the wet and don't go on the shout,
For the sickness gets in as the liquor dies out,
An' it crumples the young British soldier.
Crum-, crum-, crumples the soldier . . .
But the worst o' your foes is the sun over'ead:
You must wear your 'elmet for all that is said:
If 'e finds you uncovered 'e'll knock you down dead,
An' you'll die like a fool of a soldier.
Fool, fool, fool of a soldier . . .
If you're cast for fatigue by a sergeant unkind,
Don't grouse like a woman nor crack on nor blind;
Be handy and civil, and then you will find
That it's beer for the young British soldier.
Beer, beer, beer for the soldier . . .
Now, if you must marry, take care she is old --
A troop-sergeant's widow's the nicest I'm told,
For beauty won't help if your rations is cold,
Nor love ain't enough for a soldier.
'Nough, 'nough, 'nough for a soldier . . .
If the wife should go wrong with a comrade, be loath
To shoot when you catch 'em -- you'll swing, on my oath! --
Make 'im take 'er and keep 'er: that's Hell for them both,
An' you're shut o' the curse of a soldier.
Curse, curse, curse of a soldier . . .
When first under fire an' you're wishful to duck,
Don't look nor take 'eed at the man that is struck,
Be thankful you're livin', and trust to your luck
And march to your front like a soldier.
Front, front, front like a soldier . . .
When 'arf of your bullets fly wide in the ditch,
Don't call your Martini a cross-eyed old bitch;
She's human as you are -- you treat her as sich,
An' she'll fight for the young British soldier.
Fight, fight, fight for the soldier . . .
When shakin' their bustles like ladies so fine,
The guns o' the enemy wheel into line,
Shoot low at the limbers an' don't mind the shine,
For noise never startles the soldier.
Start-, start-, startles the soldier . . .
If your officer's dead and the sergeants look white,
Remember it's ruin to run from a fight:
So take open order, lie down, and sit tight,
And wait for supports like a soldier.
Wait, wait, wait like a soldier . . .
When you're wounded and left on Afghanistan's plains,
And the women come out to cut up what remains,
Jest roll to your rifle and blow out your brains
An' go to your Gawd like a soldier.
Go, go, go like a soldier,
Go, go, go like a soldier,
Go, go, go like a soldier,
So-oldier OF the Queen!
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Funny how you can get a degree in optics and never encounter a lens being deformed by the shock loading of transmission of laser pulses. Youngs is the rate of change of stress with strain, and in optics is VERY commonly used as the operating principle of polariscopes, polarimiters, etc.
Sigh. Yes, I know the definition of young's modulus, and it's application in optics is how I'm aware of it. And to be honest, I've never dealt with deformation of lenses by high-energy laser pulses in practice. Or, to put it another way, I've never come across an application that needs to have that factored in. It's most likely out there.
Can I do the math (for an engine), you ask. Yes I can.
Good. Care to share? Or are you of some deviant personality style that knows the answers, but will not help a person find them? Don't let me reinvent the wheel here. If you care about the safety issues as much as you claim, you'll let me know. Drop a hint or something. I'm all ears.
People come in two flavours, those that prefer to be able to ask a question and get an answer, and those that prefer to to learn. The latter are in the minority.
he easy way to differentiate between them are the book learners and the thinkers. Book learners are always quick to do things like reach for spreadsheets and start banging made up (as opposed to tabulated from instruments over time) numbers into the first formula they found that appears to fit the bill.
(.......Lots of drivel deleted about accidents and lucky/unlucky people Guy_F knows, but don't really advance his point further than the above statement...... and a poem too! Niiice.)
I don't think it's quite as clear cut as you make out, but anyway....
So.... let me get this straight. The people that take the time to at least attempt to do the calculations before going ahead and getting themselves in trouble aren't the thinkers? And the people that go ahead, get in trouble, but are saved by some other safety feature are the one's in the right? Is this assuming that all non-thinking people that do the calculations aren't going to have that extra safety feature? Perhaps some people are like that, but I'm not one to blindly trust the numbers, even though I quote them a lot. Numbers are a useful guide, and even to be within an order of magnitude is enough to get a handle on it to factor in some level of safety. I'm pretty sure that in all the posts here, I've never advocated going out there and just fiddling around after you've put together some half-arsed numbers. Hmmm. I think I even mentioned a 10X factor of safety for the forces. And posted that if real-world results differ while you're trialling it , you need to stop and find out why. But what do I know, I don't fit into your definition of a thinker.
I know you got fancy tables for risk assesment, that's what they are called anyway, but the purpose isn't to mitigate risk, it is to wash your hands when the numbers come up, hey, we did a risk assessment, so we ain't culpable.
I will only say this once to you Guy_F:
Risk assessment is not about ass-covering. It's about people not getting hurt. Period.
The calculations that I do to at least try and determine forces involved are a part of that risk assessment. They could be hideously wrong. But they are my best effort at reducing the risks involved to a manageable amount.
If you truly believed all your words you bleat about safety, you would gladly share your knowledge and numbers with me.
I've asked you publically and PM'd you for any more detail regarding those engine loading experiments. If someone has the numbers, I'd like to know, so I can at least try and calculate a factor of safety.
Good thing we're not talking in a bar here Guy_f, after your statement about risk management, we'd be fighting in the street at this point.
Added, after calming down somewhat: The reason I get worked up about your poo-poohing of risk assessment is that it keeps me alive in my job where many hazards are present. Yes, it's a bonus for my employers that they don't have to pay out for all the severed limbs of course - and in these legal times a risk assessment is not a CYA anymore if someone gets hurt. Your examples given are good examples for the case for proper risk assessment - the fact that the one guy that was uninjured took the time to assess the risks and make sure cover was present indicates that if the others had done the same, they'd be uninjured or alive now.
And in any risk assessment you try and include everything - "So what would happen if it *did* break?" is a part of that, particularly if you can remember to say "Do I trust the numbers that we came up with for the strength of that thing?". If you don't continually keep doing that kind of thing, you end up with accidents.
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Damn Guy i can't help but like ya! if anything you sure are entertaining :)
i follow your rational on the use of formulae and spread sheets to develop or support the development of anything where there are many variables , some of which either are not known, or cannot be known and assumed.
assumptions get you into trouble everytime, and working with unknowns are just as dangerous, working with variables that cannot be known is an exercise in futility, in my experience.
i have been doing a butt load of reading on this subject, basically to get a pattern of thought from many sources.
there is much written on the difficulty in modeling this sort of thing (engine mounting) so empirical testing seems to be the norm and the most expedient in getting the thing done, that is if it can be done.
where i can see math, equations, calculations etc being useful is if i knew for sure all the variables and even then i would use the answer as a starting point and would expect to hopefully be in the ballpark, but i would also accept straight up that the answer might be way off of the reality.
having said that i do have a question, and it is a genuine question, that has bothered me over the run of this whole topic.
first i would like to preface the criteria
1. an engine that is running on a hard/rigid/dense block such as concrete, the shock that is delivered to the crankshaft via the conrod, travels thru the main brgs, thru the case, thru the mounts and to the block. with every action there is an equal and opposite reaction, and it would appear that a significant amount of the shock is sent right back up the chain to the crankshaft. obviously the lister design is strong enough that this is of no concern.
2. an engine that is resilient mounted either on rubber or on a block of concrete that is sitting on wet clay, will have some movement, this movement appears to do two things, one it absorbs a significant amount of the shock sent down the crank as in #1 above, but .. two, it also allows the flywheels to change plane, and impart forces back onto the crankshaft from gyro forces simply stated
which of these two are you most concerned with? i would assume from thinking about this and what you have said it would be #2 as #1 has not been an issue with the original engine.
if it is #2 as i assume, is the real issue the crankshaft is not sufficiently heavy in cross section or design to carry 300# of flywheels and be allowed to move at all which would force it to counter or lever against gyro forces?
just thinking
bob g
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Dammit Bob, I didn't want to have to start thinking! :)
Aye, assumptions can bite you in the ass. But sometimes assumptions can help you appreciate the forces involved. If , by a few assumptions, you work out that the forces are "large" , then you can take steps to take your large forces into account.
Anyway, regarding your questions:
A couple of things :
- One would presume that the forces exerted by the counterbalance in each flywheel are quite large at speed. This isn't just your normal "imbalance" that we have from poor manufacturing, its the entire balance weight needed to offset the piston/conrod mass. somebody did work out what it should have been, a couple of pounds at that distance? It's a pretty big force at 650RPM. It appears the crank can sustain that sort of force for a goodly period of time - that is, not many listers or listeroids of questionable balance have broken crankshafts. And listers of good balance that have "normal" counterweight forces have sustained 100,000 hours without broken cranks.
I'll try and step through it one more time.... maybe I should put it graphically with a picture.
A single cylinder listeroid operating is out of balance, by definition. So the centre of mass is offset from the centre of rotation a little bit. Not much really, when you take into account all that mass from the flywheels, but it is offset. Applied forces shift the apparent centre of motion as well, basically acting as a weight on an arm.
So , to reiterate, if you simply had a crankshaft and two flywheels spinning in the air, they wouldn't spin directly on the centreline of the crankshaft, the crankshaft centerline would actually spin in a little circle, due to the centre of mass being offset from the centre of rotation - the whole thing's unbalanced. Like an unbalanced washing machine, the whole thing wants to spin around it's centre of mass.
Now , if I slapped a pair of bearings on the crankshaft, and let them spin around with the rest of it, the only force on the bearings would be the force needed to move the bearings around the centre of mass. Not much force really, bearings don't weigh that much.
Go to the whole other extreme now - fix those bearings solid and make everything rotate around them - and the force on the bearings is now something else entirely.
It can be condensed to the entire mass of the two flywheels and crankshaft rotating on an arm that is the distance from centre of mass to the centre of rotation. There will be bending forces on the crankshaft where the counterweights on the flywheels - and the forces from the conrod - try and move the fixed bearings causing a bit of flex.
So from there to the middle ground : If the bearings are allowed to oscillate a little - basically "chase" the actual centre of mass of the entire mass of "Flywheel - crankshaft - Flywheel", then the closer they are at getting to the centre of mass - which the whole thing wants to rotate around - the less bending force is exerted on the crankshaft.
Can anyone follow this, or should I just lay off the drugs?
With the Gyro forces .... isn't that only generally applicable when you try and twist the axis of rotation at 90 degrees to the spinning object? (eg, viewed from the top of a listeroid, twisting left and right). Simple motion up/down/left/right in the same plane doesn't generate it, correct?
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Damn Guy i can't help but like ya! if anything you sure are entertaining :)
i follow your rational on the use of formulae and spread sheets to develop or support the development of anything where there are many variables , some of which either are not known, or cannot be known and assumed.
assumptions get you into trouble everytime, and working with unknowns are just as dangerous, working with variables that cannot be known is an exercise in futility, in my experience.
i have been doing a butt load of reading on this subject, basically to get a pattern of thought from many sources.
there is much written on the difficulty in modeling this sort of thing (engine mounting) so empirical testing seems to be the norm and the most expedient in getting the thing done, that is if it can be done.
where i can see math, equations, calculations etc being useful is if i knew for sure all the variables and even then i would use the answer as a starting point and would expect to hopefully be in the ballpark, but i would also accept straight up that the answer might be way off of the reality.
having said that i do have a question, and it is a genuine question, that has bothered me over the run of this whole topic.
first i would like to preface the criteria
1. an engine that is running on a hard/rigid/dense block such as concrete, the shock that is delivered to the crankshaft via the conrod, travels thru the main brgs, thru the case, thru the mounts and to the block. with every action there is an equal and opposite reaction, and it would appear that a significant amount of the shock is sent right back up the chain to the crankshaft. obviously the lister design is strong enough that this is of no concern.
2. an engine that is resilient mounted either on rubber or on a block of concrete that is sitting on wet clay, will have some movement, this movement appears to do two things, one it absorbs a significant amount of the shock sent down the crank as in #1 above, but .. two, it also allows the flywheels to change plane, and impart forces back onto the crankshaft from gyro forces simply stated
which of these two are you most concerned with? i would assume from thinking about this and what you have said it would be #2 as #1 has not been an issue with the original engine.
if it is #2 as i assume, is the real issue the crankshaft is not sufficiently heavy in cross section or design to carry 300# of flywheels and be allowed to move at all which would force it to counter or lever against gyro forces?
just thinking
bob g
Assumptions will kill you bob, you know this, you state this, then you ask a series of questions based on an assumption.
if there are 100 factors and you think there are 99 or only know the answers for 99 then you do NOT have an approximately accurate answer, you have something that is LESS use than a number pulled out of your ass, because you don't bet your life on a number pulled out of your ass.
incognito is talking about building a test rig, but he ain't building a test rig, he is just talking about it, he is building a real rig, the difference between a ricardo variable compression test engine and dynamomenter and a CS, the test rig serves no purpose but to test, and no matter what breaks it has belt and braces, and it only ever gets you basis starting data.
you ask the question that the lister way and incognitos way are both basically isolastic mounts.
yes they are, in theory.
in practice there are two huge differences.
1/ the lister way has mass, change that and you change EVERYTHING
2/ even if we assume the two systems are identical in theory, you are missing a fundamental point because you aren't using your brain or your eyes, you aren't thinking, you are being mesmerised by bullshit.
The difference is one is a large and massive system, and the forces at work are distributed weakly over large masses and through large contiguous volumes of material, and the other system focuses all that effort and work at extreme density and flux through very small masses and through very small volumes of material.
5 pounds weight will support your back nicely when applied to a cushion, the same weight wil drive a sharpened spike right through your body.
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Funny how you can get a degree in optics and never encounter a lens being deformed by the shock loading of transmission of laser pulses. Youngs is the rate of change of stress with strain, and in optics is VERY commonly used as the operating principle of polariscopes, polarimiters, etc.
Sigh. Yes, I know the definition of young's modulus, and it's application in optics is how I'm aware of it. And to be honest, I've never dealt with deformation of lenses by high-energy laser pulses in practice. Or, to put it another way, I've never come across an application that needs to have that factored in. It's most likely out there.
Can I do the math (for an engine), you ask. Yes I can.
Good. Care to share? Or are you of some deviant personality style that knows the answers, but will not help a person find them? Don't let me reinvent the wheel here. If you care about the safety issues as much as you claim, you'll let me know. Drop a hint or something. I'm all ears.
People come in two flavours, those that prefer to be able to ask a question and get an answer, and those that prefer to to learn. The latter are in the minority.
he easy way to differentiate between them are the book learners and the thinkers. Book learners are always quick to do things like reach for spreadsheets and start banging made up (as opposed to tabulated from instruments over time) numbers into the first formula they found that appears to fit the bill.
(.......Lots of drivel deleted about accidents and lucky/unlucky people Guy_F knows, but don't really advance his point further than the above statement...... and a poem too! Niiice.)
I don't think it's quite as clear cut as you make out, but anyway....
So.... let me get this straight. The people that take the time to at least attempt to do the calculations before going ahead and getting themselves in trouble aren't the thinkers? And the people that go ahead, get in trouble, but are saved by some other safety feature are the one's in the right? Is this assuming that all non-thinking people that do the calculations aren't going to have that extra safety feature? Perhaps some people are like that, but I'm not one to blindly trust the numbers, even though I quote them a lot. Numbers are a useful guide, and even to be within an order of magnitude is enough to get a handle on it to factor in some level of safety. I'm pretty sure that in all the posts here, I've never advocated going out there and just fiddling around after you've put together some half-arsed numbers. Hmmm. I think I even mentioned a 10X factor of safety for the forces. And posted that if real-world results differ while you're trialling it , you need to stop and find out why. But what do I know, I don't fit into your definition of a thinker.
I know you got fancy tables for risk assesment, that's what they are called anyway, but the purpose isn't to mitigate risk, it is to wash your hands when the numbers come up, hey, we did a risk assessment, so we ain't culpable.
I will only say this once to you Guy_F:
Risk assessment is not about ass-covering. It's about people not getting hurt. Period.
The calculations that I do to at least try and determine forces involved are a part of that risk assessment. They could be hideously wrong. But they are my best effort at reducing the risks involved to a manageable amount.
If you truly believed all your words you bleat about safety, you would gladly share your knowledge and numbers with me.
I've asked you publically and PM'd you for any more detail regarding those engine loading experiments. If someone has the numbers, I'd like to know, so I can at least try and calculate a factor of safety.
Good thing we're not talking in a bar here Guy_f, after your statement about risk management, we'd be fighting in the street at this point.
Added, after calming down somewhat: The reason I get worked up about your poo-poohing of risk assessment is that it keeps me alive in my job where many hazards are present. Yes, it's a bonus for my employers that they don't have to pay out for all the severed limbs of course - and in these legal times a risk assessment is not a CYA anymore if someone gets hurt. Your examples given are good examples for the case for proper risk assessment - the fact that the one guy that was uninjured took the time to assess the risks and make sure cover was present indicates that if the others had done the same, they'd be uninjured or alive now.
And in any risk assessment you try and include everything - "So what would happen if it *did* break?" is a part of that, particularly if you can remember to say "Do I trust the numbers that we came up with for the strength of that thing?". If you don't continually keep doing that kind of thing, you end up with accidents.
you should do a risk assesment before inviting people out into the street.
I don't know your age but I do know you are young and naieve, risk assement ain't about saving lives, cos first you need to quantify the value of life and limb in dollars in that particular market, risk assesment is exactly what I said it is, we ain't culpable m'lud cos we did this here risk assessment,see.... one day you will learn enough to see the truth in this.
re your question, you asked the question a dozen time, and I answered it a dozen time, your method is wrong, it is bad practice, it is whistling in the dark.
your problem is you lack the experience and mental discipline to see the problem clearly,
you are exactly analogous to those people, and most of them have ridden bikes for years, who know for a fact because it is obvious because it is common sense because they thought it through without any mental discipline or experience, that you turn the handlebars on a motorcycle right if you want to turn right, the reality is you don't even need to turn them, you just apply force, precession will do the rest, and you apply the force to turn the bars left if you want to turn right, more force for a sharper turn, that force causes the precessive forces and those forces cause the system to lean one way or another and that causes changes in wheel geometry and thats what makes the bike turn.
only way to teach people this is send them out on a wide straight empty road, put your left hand across on the right bar and try and go straight, you learn or suffer a great deal of pain.
pain is a good tutor.
risk assessment my ass, a PROPER risk assessment will include bloody idiots like you who think they can calculate everything and take shortcuts and make assumptions and walk away from it, the most dangerous part of a motor vehicle is the nut behind the steering wheel. He assumes he is a good driver and in control and nothing unexpected is going to happen.
like I said, inquests suck.
I was the one who found JC's head, still in his safety helmet, and had to fish it out from under where it was jammed, I was the one who had to go tell his missus what happened, and it was real quick, so you can't tell her the canadian ex logger was a real sharp edged bastard with his two eggs side by each but he was smart and didn't trust the assholes he was working with because he knew he didn't know it all and he knew they didn't have the same attitude as him, so he lived and JC died, because JC listened to their bullshit and attended the safety meeting and planning meeting and didn't realise everyone was doing what everyone always does, signing off on bullshit and assumptions, because nobody had the guts to stand on their own convictions and say "we don't have the kit on site to do this job safely".
Things never used to be done like that, it never used to be that assholes got to keep asking the same question until they got the answer they liked.
Many years ago (true story) in sheffield there was a large furnace that was used to pour a speciality steel, various buy outs went through and the new management spent millions on a computer system to control the pour and sacked the old guy who used to decide when to pour, quality and consistency plummeted, they spent more millions on more computers and consultants and made incremental improvements, but still nowhere near the quality and consistency they used to have, so one day one wag decided to call the old boy they sacked in, he comes in, free or charge, for one day and tells them when to pour, suddenly quality and consistency was back up to old levels.
The bean counters (like you) who were convinced that if an old man could do it they could do it with enough number crunching tried again, more millions and more time, and improved it some, but it was still shit compared to what the old man used to do, day in and day out.
The had accidents too, pouring hot steel is dangerous, get it slightly off and you get fountains of molten metal that fly further than you were expecting.
Eventually they went back to the old man, and management was there when he came back in for the day.
He made them sit there and listen to the old days, when sheffield also had many small glassworks, before assholes like them got into management and closed them down, and one old boy in one of the glassworks made him up this small rod of coloured glass that he used to hold in his fist, so nobody saw it and assumed be was just squinting and using his hand as a shield from the heat, but he was watching for a colour change in the melt through this glass rod, and when he saw it he'd tell them to pour.
So they got their answer, a piece of glass and an old mans skill and experience got a result that they simply could not hope to duplicate with computers and numbers, so even though they had the answer to their production, quality and safety problems handed to them on a plate for free they couldn't use it, and said it was useless to them.
If you go to that site today there is a shopping mall and cinema multiplex there. The old man is long dead and only his memory lives on in people like me who re-tell the story now and again.
The answer to the questions you keep asking me is tied up in that story, but you won't see that, you aren't equipped to see that, and so you, like that steel company, won't ever get an answer that is any use to you, and like the steel company you won't accept that that represents a failing on your part, and not an inadequate answer.
But, you won't give up your spreadsheets and pulled out of your ass calculations, because without them what have you got? You don't want the hard way, you don't want the experience and mental discipline, you want quick answers, you don't care that they are wrong, you just want quick.
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I don't know your age but I do know you are young and naieve, risk assement ain't about saving lives, cos first you need to quantify the value of life and limb in dollars in that particular market, risk assesment is exactly what I said it is, we ain't culpable m'lud cos we did this here risk assessment,see.... one day you will learn enough to see the truth in this.
You old cynic. I will agree to disagree on this, otherwise we'll be here all week.
re your question, you asked the question a dozen time, and I answered it a dozen time, your method is wrong, it is bad practice, it is whistling in the dark.
So, doing some theoretical work before going out there and doing it in practice is bad? How many people do you kill when you're off trying something for the first time? Surely you try to get some idea of what's going to happen beforehand? And the principles of vibration isolation - while complex, granted - are hardy some inscrutable black art. Ok, maybe the fine-tuning is.The "get it to the stage where it likely won't kill anyone" part isn't.
Lots of anaolgies based upon assumptions skipped
Risk assessment my ass, a PROPER risk assessment will include bloody idiots like you who think they can calculate everything and take shortcuts and make assumptions
Why, I believe we agree here! See the final words of my previous post. But I will disagree with you when you think I am the one taking a shortcut. I could go out to the shed and bang up a frame and off I go into the sunset, until 10 years later under some particular load and speed, it all falls apart. I'm the one taking the long way round , testing my patience with people who make assumptions on my intentions and want to slot me into some box that I don't fit into. I don't care what your opinions are of number crunchers. Number crunching serves a purpose when you're off in the great unknown trying to work out a solution that won't kill anyone. Or I suppose I could simply agree with you, go test a frame and kill someone by accident. ("M'lud! I was experimenting with some rubber mounts and it reached resonance, flung off it's flywheels and killed someone. Yes, I know, resilient suspension designs have been proven for decades, m'lud. Yes I know that there's formulae that will put me in the right ballpark without all this dangerous experimenting, but... A foolish act, m'lud? Guy_Fawkes recommended it! Surely he is the authority on risk and covering his ass...")
I was the one who found JC's head, still in his safety helmet, and had to fish it out from under where it was jammed, I was the one who had to go tell his missus what happened, and it was real quick, so you can't tell her the canadian ex logger was a real sharp edged bastard with his two eggs side by each but he was smart and didn't trust the assholes he was working with because he knew he didn't know it all and he knew they didn't have the same attitude as him, so he lived and JC died, because JC listened to their bullshit and attended the safety meeting and planning meeting and didn't realise everyone was doing what everyone always does, signing off on bullshit and assumptions, because nobody had the guts to stand on their own convictions and say "we don't have the kit on site to do this job safely".
All arguments aside - you poor bastard. I'm truly sorry you had to go through that.
What I am trying to do is pin down the details further, instead of just going off and making a frame that I assume will be fine, but in reality will wind up killing someone. Which I think is the kind of assumption that you're railing against. I think. I'm happy with ballpark figures and large margins. All I want is indicative loads and resonances to make sure the thing I build is strong enough that I can test further without it all going pear-shaped.
But, you won't give up your spreadsheets and pulled out of your ass calculations, because without them what have you got? You don't want the hard way, you don't want the experience and mental discipline, you want quick answers, you don't care that they are wrong, you just want quick.
Wrong guy_fawkes, terribly wrong.
I don't want quick. As I mentioned before, If I wanted quick, I wouldn't be mucking about with spreadsheets and dealing with crap from you. So I put my spreadsheet away, then what? You don't seem to know squat about resilient mounts. But you think I should go out and start dicking about trying to do something, ignoring all the numbers (because they're based on figures that are ill-defined)? I'd be out there making a nice-looking frame, which would likely be overstressed and fail terribly. I don't want quick, I want the right answer. Seeing that your answer is "Don't use a resilient mount", and you cannot tell me any good reason why not except "That's The Way It's Always Been Done", I will now hereby slot you into the box that says "Part of the Problem."
I'll happily give up my spreadsheet if someone has a nice, resilient mount design that does the job and isolates that thumping great big bit of iron from the rest of the world. Oh wait, no-ones got that yet? Well, back to the spreadsheet. There'll probably be plenty of tweaking and tuning involved in the real-world, and I'm genuinely interested in whether the spreadsheet lands me in the right ballpark , or whether it's miles off.
Oh, and you say you can calculate the forces involved? And you say that you've done testwork with engine forces under load? Still haven't seen any details, Guy_F. If you want to convince me, don't bother with the long stories. Give me hard facts, design tips or numbers for the problem at hand. Otherwise you're part of the problem, not part of the solution and you'll have no more time from me.
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GF:
i will have to respectfully disagree on your assessment of my use of assumptions as being dangerous,
assumptions are like hypothesis, for the purpose of asking a question, quite apart from assumptions used to design and build something.
if you recall i asked a couple of questions!
so far i am not getting a direct answer, but rather a tangent.
perhaps i am not making my question clear, or it is getting caught up in all the verbage.
so let me restate,
you have made reference as to your concern for the crankshaft breaking if not solidly mounted as lister prescribed, so
is it because the crankshaft is of insufficient strength to put up with forces imparted back to the crankshaft by means of fighting against the flywheel gyro effects, or by some other means?
please explain
bob g
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About crankshaft flex – and the change in that which would occur in a (more) resilient mounted engine…
I’d suggest that one imagine a stationary crank and flywheel set up with bearings that allow some significant angular rotation on the main-journal axis. Ordinary bearings do this. For clarity imagine that the rod journal is at TDC. Now imagine that the bearing housing-carrier set is accelerated along the axis of the cylinder. The mass of the flywheels will cause the crank to bend – mostly in the rod journal and web region – that’s where the force is concentrated. (If one placed an inside mike on the rotational axis under the rod journal they could measure the deflection – and we do this in large stationary engines to assure proper as-found alignment.) Now reverse the acceleration. Repeat. The engine is bouncing and the crank follows, bending first one way and then the other. In practice, with the engine actually rotating, this flexation would occur, I suppose, 1300 times per minute at 650 revs. It is not a uniform sinusoidal motion however, because the power flow into the system follows a four-stroke pattern with the piston power stroke creating a one-in-four event. In practice the motion is somewhat rotational, but for simplicity…
Now consider that the crank is in reality a torsional spring (it is). By allowing the axial bending moment to increase relative to the as-built torsional deflection (by resilient mounting) we have changed the loci of stress in the crank web, and I expect, increased it too. That is unknown territory. One might even create a critical oscillation.
All this exists whether the engine is mounted on 6000 pounds of concrete or floating in space – but the amount of flex and the pattern of flex changes.
In practice I suspect quite strongly that the effect of resilient mounting is similar to what would occur with a misaligned rigid shaft coupling. The effect, if large enough, will cause excessive web deflection and a time-to-failure “clock”.
Additional outboard bearings, properly supported, would mitigate this effect. That’s a complex and expensive undertaking and I would not wish to attempt it, but if done right it would surely eliminate most of the web deflection increase that (more) resilient mounting creates. (As a matter of fact in Kawasaki racing kart engines an additional outboard main bearing is a more or less standard racing modification - ‘cause otherwise they snap cranks.)
In another line of thought I'd like to applaud the seveal of you all who have emphasised the importance of safety - "doanwanna git anybuddy kilt 'r hurt" - what's life about anyhow if not to have a good time? Can't do that if we hurt people.
Best, Phaedrus
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So after some research I see the Indians started putting the TRB in the 6/1....With out the revision approval of LISTER. All this rubber or not to rubber debate going on, and we arn't following the directions of Lister will cause them to explode. My question is with all these invisable forces going on don't the TRB apply latteral forces to the case? I seems they would be directly related to the rotating plus firing pulses...Just a thought!....they seem to handle this modification without any problems. Sure is a different load applied than with straight bushings.
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Guy:
sorry i had to go make some money, now i am back
"2/ even if we assume the two systems are identical in theory, you are missing a fundamental point because you aren't using your brain or your eyes, you aren't thinking, you are being mesmerised by bullshit."
i don't assume the two systems are identical in theory, rather they exhibit some of the same behaviors, based on differing variables
at this point you are correct i am thinking, and not useing my eyes and brain as i do not have a sytem in place to observe and measure
as far as being mesmerised by bullshit, i assure you i am not.
you like to site master ricardo and his work, do you not suppose he did a lot of thinking before he built any test rig, beit a variable compression test engine or whatever?
further, do you not suppose it is likely even after building the test engine and getting some data, he applied it into alot more thought before building anything?
i am not talking about a redesign or suggesting anything,,, i am simply asking a question
what evidence makes you believe the crankshaft is in danger of breaking in a resilient mounted engine?
do the portable lister units have a higher rate of crankshaft failure?
do the engines used in other non stationary applications have a higher rate of failure?
are we to conclude the reasoning that a lister/oid should not be resiliently mounted because of breaking crankshafts as a supportable
conclusion, or an assertion, or theory , or a feeling?
my feeling is yes there might be a higher failure rate, but i have no documentation to support the feeling, do you?
my theory might also be that a resilient mounted engine imparts stresses on the crankshaft that are not prevalent in a concrete mounted engine,
and these stresses should shorten the life of the crankshaft, but i have no documentation to support this theory,, do you?
i could assert the same as above, but have no documentation to support my assertion, do you ?
so how am i to conclude that there is significant risk of failure?
i would suspect that a poorly balanced engine would have as much or more effect on failure of a crankshaft, whatever way it is mounted, but
i don't have documentation to support that either.
Guy if you don't know, Just say so. no harm in that is there?
i will tell you straight up i dont know! that is why i continue to ask, perhaps someone might stumble across this subject and one day in the future come across the
answer.
a while back you stated that i am playing devils advocate on this subject, in some ways i probably am.
the primary reason i question and debate this thing with you and others is not to necessarily come to an answer as the primary reason for doing so.
rather it is the journey and the process that brings out other information, procedures, and thought that has a much wider application that may very well have
nothing to do with lister/oids.
bob g
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Good point about TRB interaction possibilities, yet plain journal bearings allow considerable axial deflection - they have to because of the oil clearance. That same clearance probaly provide cushioning and damping of transient accellerations perpindicular to the crank axis - the TRB types may well have higher crank stresses...
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Good point about TRB interaction possibilities, yet plain journal bearings allow considerable axial deflection - they have to because of the oil clearance. That same clearance probaly provide cushioning and damping of transient accellerations perpindicular to the crank axis - the TRB types may well have higher crank stresses...
and case stresses....the taper bearings would try to spread the case under load...?!
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Maybe its the booze....
But this started getting interesting again....
Doug
More read more beer.....
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About crankshaft flex – and the change in that which would occur in a (more) resilient mounted engine…
I’d suggest that one imagine a stationary crank and flywheel set up with bearings that allow some significant angular rotation on the main-journal axis..... (etc)
Ok... I think I've got what you're on about there. But - a query:
The resiliently mounted engine and bearings are moving from the applied forces on them. The forces are generated from the crankshaft/flyhweel rotation and combustion forces applied to them. The crank isn't following the engine when the engine jiggles, the engine is following the crank and flywheel about the place as they jiggle. So if the engine *can* follow the crank/flywheel a little - as I postulated about it rotating around the apparent centre of mass - surely this reduces the axial deflection on the crankshaft as opposed to a rigid mount?
It does lag by a certain amount, so there'll be a point where the crankshaft zigs and the engine zags a little. It really depends on your damping forces and whether you're near resonance in your resilient mount as to whether it gets seriously out of phase.
In another line of thought I'd like to applaud the seveal of you all who have emphasised the importance of safety - "doanwanna git anybuddy kilt 'r hurt" - what's life about anyhow if not to have a good time? Can't do that if we hurt people.
Too true. I'd rather we discuss it here until we're blue in the face, before we go out,experiment, and hurt someone as a result.
As for crankshaft/crankcase forces, this isn't a high-performance lightwieght motor where every last cubic mm of unnecessary metal is removed from the engine. From the stories of various hideously-imbalanced listeroids chasing people around the place, and no doubt hundreds of firmly-anchored-yet-very-unbalanced engines running fine, it's indicative that they're plenty strong enough to handle a heap of abuse. The clock's still ticking, but whether it goes off in 5000 hours or 50000 hours is the problem. 50000 hours, I could handle that. 5000 hours, well , personally I'd shrug philosophically and call it a learning experience.
Anyone know if there's much change between a 6/1 crank and the crank from a higher-powered single-cylinder variant?
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i also understand what i have seen in the field, engines that are rigidly mounted to a subframe, that are meant to be
a moveable stationary engine (such as oil field mud pumps) break crankshafts quite easily if dropped a very few inches from the truck that is placing them ( i might add on the ground not concrete). whereas
the same engine mounted resiliently in a truck can sustain being dropped the same distance without breaking the crank.
no granted neither engine was running when the cranks broke and as such the failure was from shock loading. but the principle seems to be the same. just happens much quicker instead of over time.
come on somebody educate me
I have seen a few cranks "sprung" from the engine being dropped in the factory. Interestly enough, when they are spinning and are dropped they have no problems in this area.
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Hmmm. Forum software ate my last post, so abridged version follows:
I have seen a few cranks "sprung" from the engine being dropped in the factory. Interestly enough, when they are spinning and are dropped they have no problems in this area.
I would presume it's from the fact the angle that the crankshaft rotates spreads the decleration forces so they they are - on average - applied over an arc as opposed to a single direction. eg, if the crankshaft could rotate 180 degrees , then the maximum amount of bend at the end of deceleration would be at 90 degrees to the deceleration force applied.
Makes me wonder if this would be a bit of a saving factor when running a listeroid on a jiggly mount, but I still think we're looking at it from the wrong side of things. That is, the engine's not jiggling the flywheels, the flywheels are jiggling the engine. There are phase differences - at various RPM's around resonance, the flywheels will lead or lag the engine motion. But it's a case of the flywheels shoving the engine about - and those applied forces trying to move the engine (and flex the crank) are there regardless of whether the engine's fixed or not.
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My quest for resilient mounts has hit a bit of a bump. The engineer I was talking to referred me to http://www.acemount.com/ The engineer at Ace specked out 2 series “E” 50 durometer in series on the engine side and 2 series “E” 40 durometer in series under the gen head side of my frame. These mounts were made by Firestone and cost $27 each so $27*8 = $216 not bad.
I did a little more research and found that the Firestone patent had expired and there were manufacturers who sold copies of the original design, one of them was a company in Chicago that the Lister Petter engineer suggested I contact, I forget the name of the co. They only sell in quantity, so they suggested I call Mcmaster.
The mounts are available at Mcmaster (pg1253 style #6 , ½” diameter) for under $10 each. I ordered 2 50A 800lb rating and 2 40A 375lb rating, thinking that if I used only one per corner it would be “stiffer” than using 2 in series per corner. This did not work; they are way too soft and allow far too much deflection. I assume that having 2 in series would make this condition worse not better. I have not spoken to the engineer at ACE about this yet. It may be as simple as adding the 2 additional mounts per side.
I may try some higher rated mounts, like the 70A rated at 1425lbs. I have read that some people have used conveyer belt under their frame, where is this available? If there are people reading this that have their engines mounted on some kind of flexible material please let us know what you are using. Please post as much detail as you can, composition of material, thickness of material, lbs rating if available, where purchased, and pictures would be great and a video clip of your running engine would be even better!
I will post any further progress good or bad. This particular resilient mounting scheme is not as good as a solid mount to concrete.
Scott
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Scott,
I used 5/side of McMaster Carr p/n 9376K131 rated for 125# ea
They are mounted between the generator frame and the base frame. I get maybe 1/4" movement on start up and shut down. I have 4/side now and it works fine. I am going to add 1 more / side to see if it is better or worse. You can set it on concrete and it will stay put. There are 2 frames on my setup....one for the generator/motor and one that isolates the radiator fuel tank, and elec box. The mounts are between the 2. I have a 2x4 under each side of the outer frame to help it stick in place on slick surfaces. I will say that how well your engine is balanced is the secret!
I'm shakin more than the Lister.
http://video.google.com/videoplay?docid=-9194771268947755783
http://www.solisstyle.com/ims/pic.php?u=4937b9lqq&i=64160
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I ordered 2 50A 800lb rating and 2 40A 375lb rating, thinking that if I used only one per corner it would be “stiffer” than using 2 in series per corner. This did not work; they are way too soft and allow far too much deflection. I assume that having 2 in series would make this condition worse not better. I have not spoken to the engineer at ACE about this yet. It may be as simple as adding the 2 additional mounts per side.
Deflection when running, I take it? How much do they deflect when loaded and not running? Extra mounts in parallel as opposed to series is the same as getting a stiffer mount - the load is shared across two mounts instead of one, so the deflection is less. Of course, the stiffer the mount, the more engine forces are transferred through it.
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These photos were posted on this site many years ago but were apparently lost. For those interested in this subject, here are the photos again along with the system descriptions.
https://www.borstengineeringconstruction.com/Lister_Engine_Photos.pdf
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WOW, I don't know why you would bother to resurrect this topic. Between statements made using funny little symbols which mean nothing to average lay person and not describing the actions and reactions using plain English I don't think I have tried read this much dribble in a long time. If it was all in plain English then it just might be interesting as the Engineers that designed these engines obviously knew what they were doing at the time as they are still running today no matter how they have been mounted.
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WOW, I don't know why you would bother to resurrect this topic. Between statements made using funny little symbols which mean nothing to average lay person and not describing the actions and reactions using plain English I don't think I have tried read this much dribble in a long time. If it was all in plain English then it just might be interesting as the Engineers that designed these engines obviously knew what they were doing at the time as they are still running today no matter how they have been mounted.
X2!
Although I admit to being entertained for a very short while by rereading a few of the posts. In the first few paragraphs of the latest link there was enough bad "facts" to cause me to stop reading.
A good quote to remember
"The knowledgeable can present the complicated in a simple manner,, while the unknowing manage to twist the simple into total complication"
author unknown
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wow
this should prove to be quite interesting!
go get 'em Bob!
:)
bob g