concrete vs resilient mounting round 2

[mobile_bob]

ok .. now to beat a dead horse

i came across something today, and it raised an interesting question

when does a lister/oid become not just an engine but a machine?

if a lister/oid is coupled to a generator, is it now a machine?

if a lister/oid is an engine, what makes it not a machine?

answers to this question is going to be very interesting as it relates to proper mounting
it is late and i don't have the reference with me to quote from, but lets see how folks answer the previous questions, and i will
try and post the reference tomorrow

bob g

[mobile_bob]

psssst   Guy!

[hotater]

I've always thought carrying a 'load' made it a machine, so a Listeroid is a machine when it's doing work...like generating power or pumping water.
  The generator is a 'machine' with an external power source...

Ain't it??   

I'm going to have the answer to the 'solid or flexible' mounting question REAL soon.  Magic Throb II has opened it's eyes.

NOW the question is this:  If this new Jkson engine is smooth as silk how will I know?  It's bolted solid to nearly two yards of re-inforced concrete!

If it's a jumper--- will I know it?

[binnie]

Just let us know how it runs....we are all waiting for the outcome. I have a Jkson 12/2 but sitting on rubber for the moment, and contemplating the 2 yards of concrete...but will be a pretty permanent structure. I have moved my engine twice to accomodate others....hope it is in the right place when I pour all that mix.
Looking forward to a Smoothe ride. binnie

[Quinnf]

I'm not Guy, and I don't even look like Guy, which is fortunate for him, but let me bite:

I always thought a machine was a mechanical device capable of performing work.  That is, something non-living like a crowbar, capable of moving something with weight, like a Listeroid crankcase over a distance, say, off your toe, which is the definition of work as I remember it was taught back on my home planet before aliens abducted me and dropped me off here because they said I ate too much.   

Do I win anything?

Quinn

[binnie]

 Quinn,
Please pass "Go" and do not collect your $200.00.... jump "Jail" & go directly to the head of the line & collect your Double Mac. "One for the engine & the other for the service it performs" ! binnie

[Guy_Incognito]

NOW the question is this:  If this new Jkson engine is smooth as silk how will I know?  It's bolted solid to nearly two yards of re-inforced concrete!

If it's a jumper--- will I know it?

Probably not until something shears off or you see a crack developing somewhere. It all depends on the magnitude of the forces.

All other arguments aside, this is one advantage of well designed resilient mounting - you can see the machine trying to rip itself free and you generally take steps to reduce this as much as possible. Surely this has to have a positive effect on engine longevity? All that vibration goes into flexing your crankshaft/bearings/crankcase/mounting bolts and lifting your 2 thousand pounds of concrete 1/100th of an inch every engine revolution. And how much power does your system use trying to be a vibratory compactor?
 
I mention the words "well designed" above to separate it from a resilient mount that is poorly designed and merely sits at resonance once you're up to speed, giving you the impression that something is seriously wrong with your engine balance.


Guy_F's link to orbits around a centre of mass from different perspectives is spot on too. Which again (sigh) makes me point out the following:

- The applied forces on the engine come from the crankshaft bearings due to crankshaft/flywheel forces trying to make a fixed engine orbit around a common centre of mass.
- What happens to those forces if the engine is allowed to move around the centre of mass a little, as in with a resilient mount?

Think carefully about this.

I won't be replying back after this post - I've sworn off internet arguments for a while. Takes too much of my finite reserves of patience, and I need that patience elsewhere. 

[Geno]

NOW the question is this:  If this new Jkson engine is smooth as silk how will I know?  It's bolted solid to nearly two yards of re-inforced concrete!
If it's a jumper--- will I know it?

They can all be individuals but my PS 6/1 looks very much like an Indian assembled version of the kits. It shimmied in a circle on a concrete floor, no load, but was never a hopper. Its a PITA if its already bolted down but you could loosly chain it up on concrete and see what happens, hand on the rack lever of course. Did you weigh the guts for static balance? I did a half assed static balance (don't have a balance stand) and came up with 330 grams per flywheel almost opposit the the counterweights. If it made a difference it wasn't much.
Thanks, Geno

[rmchambers]

I've been mulling this over since all the discussions of late and I have to wonder about something.

Lets say, as stated above, that the forces being generated by the engine from the combustion and the unintended forces from an out-of-balance flywheel(s) are all acting upon the main bearings of the engine.

If the engine is mounted to a monolith of concrete which resists all appreciable movement then the entire force of the combustion stroke as well as the out of balance forces are acting on a stationary bearing surface.

If the engine is mounted to some sort of flexible mounting then the forces acting on the bearing will still be there but if the engine as a whole and the bearing surface in particular can move some amount then the forces brought to bear on said bearing should be reduced as they are being spread over some distance.

I'm likening this scenario to hitting something like a nail with a hammer.  Assume the force of the hammer swing is the same but one nail is in a piece of wood (allowing movement) and the other nail is pressed against something unmovable (concrete).  Which nail will deform first?  The one between the rock (concrete) and the hard place (hammer).

I can't speak from experience as I have no stationary engine yet, I'm looking to make a genset from a petteroid when I have some free cash and time to pick the stuff up, but time spent reading most of what is contained in this site is valuable and useful to me.

Thanks

Robert

[mobile_bob]

in a technical sense a lister/oid is not a machine in that by itself it produces no useful work
when coupled to a generator or a pump it now becomes part of a machine that does useful work

the reason i asked the question was based on research and what i found on the evolution of engineering as it pertains to
rigidly mount a machine

years ago it was customary to mount machines that were stationary directly to a concrete base, these machines had to be designed quite heavy because of the fact that all forces imparted on or into the concrete base were returned in amount equal to the original source or in some instances amplified and returned to the machine. as long as machines are built heavy they can and did survive very well on rigid mounts, the problem now is machines are built lighter by design and necessity.

lighter vibrating machines if rigidly mounted cannot handle these forces being returned to the machine by rigid mounting, parts fail do to fatigue. resilient mounts when properly engineered and implimented reduce by absorbing these forces from being reintroduced to the machine, and in doing so allow the engineers to reduce the physical size and strength of some of the components and in the end reduce costs.

bottom line is that there is no reason to believe that proper resilient mounts will be destructive to a machine that was originally designed to stand up to rigid mounting, if anything proper engineered resilient mounts should increase the lifespan of the machine.

also it should be stated that other component that make a lister/oid a machine such as a compressor, generator or pump, will benefit from the machine not being rigidly mounted, having stresses and vibration returned from the concrete base to the machine while not being detrimental to the lister/oid can and in many cases are destructive to these other components. it should be taken into consideration that the generator, pump, compressor etc have been balanced and provisions should be made to reduce or eliminate other sources of stress, vibration etc from being introduced to them.

i have come to these conclusions from not what i have been told, what i have been led to believe or what i feel. Rather i have come to these conclusion thru much research from multiple sources and multiple types of equipment and design. while it may be said that these other types of engines and equipment are not lister/oids, it really makes no difference, lister/oids are not atypical in design.

i also realize folks are going to mount their engines any way they so choose, and i will as well. my only point here is to raise question and to find answers to these questions and provide alternatives to those that want to think about them. some of you will think about it, some will blow it off, and the rest will have their eyes glaze over.

who knows there might be someone reading all of this who actually works as an engineer, designing mounting systems for stationary engine's, perhaps he/she will find their way here and step up and say a few words.

bob g

[Quinnf]

Robert,

That's sort of my take, as well.  Consider a ferrier frantically ferriing footware for a friendly four-footed filly.  What does the ferrier (we'll call him Fred) do?  He grabs a piece of steel and places it on a heavy, rigid anvil and bangs away, because it is his intent to deform metal.  Were he to place the steel on his knee and bang away with the same force, he wouldn't get much work done because much of the force applied to the steel would be absorbed by his leg. 

In the ferrier's frame of reference, a resilient mount (not the filly) would work against him, since it is his intent to deform metal.  However a heavy one-lung engine might also tend to deform metal (bearings) if rigidly mounted.  Seems to me the bearings would take a lot more punishment with a rigid mount as compared to an intelligently designed resilient mount. 

[Edit:  However, who here has ever heard of any Listeroid needing new TRBs?  They seem to be VERY rugged.  Even on Hotater's concrete-breaking hopper with over 7,000 hours now.  Perhaps it's because TRBs are made from hardened steel, whereas plain bearings are made from bronze, a softer material.] 

I think to compare the mounting method of a real-live English Lister engine with enormous journal crankshaft bearings to an Indian-built Listeroid with tapered roller bearings is fallacious.  The point  loading on the roller bearings is clearly much higher than on journal bearings.  So what's right for one engine doesn't make it right for the other one, simply because they're similar in _most_ aspects.

Quinn

 

[hotater]

 FOR WHAT IT'S WORTH---

I cranked the Jkson- Power Solutions kit 6-1 today for the first time. 

It's bolted to nearly two yards of concrete that is tied into 10 more yards of a well plug. It's SOLID.

Twelve feet away is a FuKing mounted to 6x6 timber frame and that's bolted to a 5 inch concrete slab, 8 x10 feet of which has cracked away from the rest of the building..

I have an accelerometer (most would call it a bed spring) that's eight inches tall and has six progressively smaller coils.
This high tech instrument records the 'nodes' of vibration from the old Listeroid out to nearly 300 feet.  On my desk, 88 feet away the spring has about .015" total movement, big end down, double that if I stand it upside down.

Today I set the spring, little end down, under the air cleaner nut of the new engine.  There is NO visible movement whatsoever.  A hand laid on the engine feels the valve lash and fuel pump cam, but NO movement.

[GIII]

But how will you tell it's running from 100 feet away??  I like a solid mount, too.  Nice work.

George

[Doug]

Happy birthday Throb II.

Little Lister in the night
Keep Hotater's lights burning bright.
Don't miss or falter threw the night.
Because Jack has built you and made you right.

Doug

[Quinnf]

Doug,

I can't help but add,

"But if you ever fail to run,
Jack will shoot you with his gun!"

Quinn