C Channel for Bracing FEL in Up Position?

[Threepoint]

Here's an interesting thought experiment: What would happen if you were to remove the cylinder piston seal?

Suppose we take a standard hydraulic cylinder with its tube end, rod end, and a piston on the end of the rod. That piston normally has a rubber seal , but for the purpose of this experiment we are going to remove the piston's seal so that it no longer fits tightly against the inner wall of the cylinder tube.

After removing the piston seal, we filll both sides of the cylinder with oil ... and while it is full of oil we put pipe plugs to seal the inlet and outlet ports.

What we end up with is a standard hydraulic cylinder full of oil, no internal seals, and no way any oil can escape - all the oil has to stay within the cylinder.

Now the question is.... Can you move the rod?

rScotty

rScotty, Oh lordy, now you've started it! Hopefully nobody will rise to the bait. :laughing: Otherwise, Suburban Plowboy's thread may end up badly like this one did a few months ago: http://https://www.tractorbynet.com/forums/kioti-owning-operating/405046-front-bucket-dropping-overnight-5.html :no:

For the answer to your question, see that thread, starting at post no. 41. I think Brian is right there, although it took me awhile to be convinced. :laughing:

 

[RickB]

It will extend if not fully extended when assembled.
If it is truly full of oil it will not retract.

 

[rScotty]

rScotty, Oh lordy, now you've started it! Hopefully nobody will rise to the bait. :laughing: Otherwise, Suburban Plowboy's thread may end up badly like this one did a few months ago: http://https://www.tractorbynet.com...405046-front-bucket-dropping-overnight-5.html :no:

For the answer to your question, see that thread, starting at post no. 41. I think Brian is right there, although it took me awhile to be convinced. :laughing:

Thanks Threepoint. I'm going to read through that old thread after we kick it around here for awhile longer.
At first I was just interested in knowing if the rod would move.
But what is starting to interest me more are the ways that people go about figuring out something like this, forming an opinion, and then coming to believe that they have it right.
Only trouble with that is so far it's looking like we only have opinions. Nobody has tried to figure it out - or hasn't posted if they have- .... and maybe that tells us something right there.
rScotty

 

[jmc]

That's an interesting mental exercise, rScotty. I should read that other thread before jumping in here but, too lazy. I'd say that unless it's an odd cylinder design like Bruce pictured, it can't be moved, even if the rod had no piston on it at all.

With both ports plugged (and a noncompressible fluid), there's a fixed volume of trapped fluid in there. Trying to extend or retract the rod tries to increase or reduce the fixed fluid volume, respectively. Nowhere to run/ nowhere to hide. For example, if you pushed the rod deeper into the cylinder, the blow-by past the piston would be more than any volume you would free up on the rod side of the piston. With a non-compressible fluid, it's locked from even starting to move.

So, as I think you inferred, the leak-down is external.

 

[Threepoint]

Uh oh. Looks like it's time to start making the popcorn. :laughing:

 

[bcp]

Here's an interesting thought experiment: What would happen if you were to remove the cylinder piston seal?

Suppose we take a standard hydraulic cylinder with its tube end, rod end, and a piston on the end of the rod. That piston normally has a rubber seal , but for the purpose of this experiment we are going to remove the piston's seal so that it no longer fits tightly against the inner wall of the cylinder tube.

After removing the piston seal, we filll both sides of the cylinder with oil ... and while it is full of oil we put pipe plugs to seal the inlet and outlet ports.

What we end up with is a standard hydraulic cylinder full of oil, no internal seals, and no way any oil can escape - all the oil has to stay within the cylinder.

Now the question is.... Can you move the rod?

rScotty

Define "you." Do you mean by hand? Or can I have powerful machinery?


When compressed with enough force, the cylinder rod will move a tiny fraction of an inch. The hydraulic fluid is maybe 1/2 of 1% compressible.

Extended with enough force, the rod could move out by creating a vacuum in the cylinder's additional space.

Bruce

 

[mikester]

Thanks Threepoint. I'm going to read through that old thread after we kick it around here for awhile longer.
At first I was just interested in knowing if the rod would move.
But what is starting to interest me more are the ways that people go about figuring out something like this, forming an opinion, and then coming to believe that they have it right.
Only trouble with that is so far it's looking like we only have opinions. Nobody has tried to figure it out - or hasn't posted if they have- .... and maybe that tells us something right there.
rScotty

The cylinder will move at a rate proportional to the volume of fluid leaking past the piston...aka hydraulic shock absorber/damper.

 

[rScotty]

The cylinder will move at a rate proportional to the volume of fluid leaking past the piston...aka hydraulic shock absorber/damper.

A hydraulic shock adsorber/damper is not quite the same thing. Both of those are more complex than the original example. Shocks and dampers have a connection to an additional compressible volume that provides the damping action.
rScotty

 

[Hersheyfarm]

This is something I do with my m62. I park it in my barn with the loader up and put the brace down. As far as leak down, sometimes the loader is sitting on the brace and sometimes the gap between the cylinder and brace I left it at is still the same. So sometimes it leaks and sometimes it doesn稚.

 

[joecdeere]

No matter which way you choose, never, ever get under the loader when raised, even for a second, it will only come down on
you once! This is one I welded up for my Ford 345C, it痴 a heavy loader, so I used very heavy angle iron, welded a foot on it to spread the load over most of the cylinder gland, then I welded a hook to line it up and hold it in place while lowering the loader down onto it. I went ahead and landed it with rubber to protect the cylinder chrome.
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