I may have discovered my curl issues on my tractor

[Egon]

Let me try to clarify (simplify)

Well that's good as I am pretty simple.


Sounds interesting but I'm afraid I am limited to understanding what the pressure is on each side of the cylinder piston.

 

[Tjdux]

Gravity is not the force that moves curl buckets down. You can curl down a bucket and lift the front wheels off the ground using hydraulic force, not gravity.

Now if you leave the bucket curl on float thats different story but any FEL i have used doesn't depend of gravity to pull it down.

 

[LD1]

Where have you been for the numerous discussions we have had on the topic.

Talking about pressure on either side of the Piston.. I have no idea what you are talking about. The pressure is irrelivant.

If the seals are shot on the piston, you will have a weak cylinder due to leaking by. Same cylinder may also drift (extend only) as fluid bypasses said wore out piston seals and a vacuum will be drawn and air potentially sicked in via gland seal.

Pressure is almost NEVER equal on either side of the Piston. If pressure WERE equal, your cylinder would be extending. (Regen cycle)

 

[LD1]

Gravity is not the force that moves curl buckets down. You can curl down a bucket and lift the front wheels off the ground using hydraulic force, not gravity.

Now if you leave the bucket curl on float thats different story but any FEL i have used doesn't depend of gravity to pull it down.

Under normal circumstances you are.right, gravity is NOT supposed to dump the bucket.

But when you have either 1. A leak, 2. A wore out cylinder or 3. A wore out valve.....

And the bucket no longer holds it's position and wants to dump (drift) all by itself.....

What force do you suppose is causing that?

 

[Tjdux]

Under normal circumstances you are.right, gravity is NOT supposed to dump the bucket.

But when you have either 1. A leak, 2. A wore out cylinder or 3. A wore out valve.....

And the bucket no longer holds it's position and wants to dump (drift) all by itself.....

What force do you suppose is causing that?

I agree with you about gravity is going to cause drift on a damaged o4 worn out cylinder...

Did you read the OPs question? He asked what amount of drift is acceptable on a machine new enough to be under warrenty.... why is this becoming a discussion about hiw hydraulics work. He wanted to know if its normal for them to drift.

Any cylinder will drift or slip down when theres a leak in the system. Clearly he has a leak, or poor seal thats all.


Also about engine being on was more reference to many older machines ive ran that do have poor seals/small leaks and i assure you drift under load will be much greater when the engine is off and the pump isnt compensating for the pressure loss. In a perfect sealed system no engine running and pump pressure will not matter, sorry for adding confusion. I was merly thinking about meachines that had drift issues.


Also the test with the jack after rereading it a few times sounds like a very good way to test. Assuming he has disconnects at the valves it shouldn't drift down if the cylinders are good.

 

[LD1]

It turned into a discussion about hoy hydraulics work because hydraulics seem to be a big mystery to many, and people just want to throw parts at a problem without diagnosis.

In the OP's opening post, his very first sentence was him "thinking he needs to get his cylinders rebuilt".

So before it is even addressed as to how much drift is acceptable.....one must understand that it can be coming from more than just the cylinders.

IMO, the cylinders should have almost no drift. Of they are drifting at all, even an inch per hour....it's worth fixing. Because you can potentially be sucking in air, water, or other contaminates.

The valve....all valves leak. There will be a mfg spec as to the amount of fluid allowed to leak past at a given pressure. All of this can be worked out with alot of math, cylinder sizes, etc. Ultimately for every inch the bucket drifts, (if it's the valve) will be displacing a given amount of oil back through the valve.

I know it's alot of rambling and no one is likely ever going to do all the math on that and look up valve specs, and pressure test. So that said, what's "acceptable" is a judgment call. If I had my forks on or a bucket load of whatever and it dumped far enough to loose a load in 5 min....yeah that's unacceptable.

But a heavy load at the end of pallet forks, over an hour's time, I'd say 3-4" at the forks would still be reasonable.

 

[Tjdux]

It turned into a discussion about hoy hydraulics work because hydraulics seem to be a big mystery to many, and people just want to throw parts at a problem without diagnosis.

In the OP's opening post, his very first sentence was him "thinking he needs to get his cylinders rebuilt".

So before it is even addressed as to how much drift is acceptable.....one must understand that it can be coming from more than just the cylinders.

IMO, the cylinders should have almost no drift. Of they are drifting at all, even an inch per hour....it's worth fixing. Because you can potentially be sucking in air, water, or other contaminates.

The valve....all valves leak. There will be a mfg spec as to the amount of fluid allowed to leak past at a given pressure. All of this can be worked out with alot of math, cylinder sizes, etc. Ultimately for every inch the bucket drifts, (if it's the valve) will be displacing a given amount of oil back through the valve.

I know it's alot of rambling and no one is likely ever going to do all the math on that and look up valve specs, and pressure test. So that said, what's "acceptable" is a judgment call. If I had my forks on or a bucket load of whatever and it dumped far enough to loose a load in 5 min....yeah that's unacceptable.

But a heavy load at the end of pallet forks, over an hour's time, I'd say 3-4" at the forks would still be reasonable.

Many times I feel these internet conversations would be much easier/faster in person. I feel were much in agreement just hard to "read" the missing bits over black and white text.

You make a good point the OP did say rebuild cylinders and its with no testing or even seeing it i would put my money on the valves just becase they are more complex but thats just a guess.

Hopefully OP gets it figured out and even better if it gets worked out under warrenty for minimum amount of trouble.

 

[LD1]

Many times I feel these internet conversations would be much easier/faster in person. I feel were much in agreement just hard to "read" the missing bits over black and white text.

You make a good point the OP did say rebuild cylinders and its with no testing or even seeing it i would put my money on the valves just becase they are more complex but thats just a guess.

Hopefully OP gets it figured out and even better if it gets worked out under warrenty for minimum amount of trouble.

This thread isn't even an "intense" one.

Some of these hydraulic threads pertaining to drift, especially the main lift cylinders, can get pretty heated. I agree, would be alot easier to tell (show) someone in person.

Those that think faulty seals can cause the main loader to drift (cylinders compressing,) and there are many here on TBN that believe this....I'd love to have a junk cylinder and 30 minutes and I would guarantee I could prove that it ain't possible.

But as it is, all I can do is the best I can trying to explain why and how hydraulics work. And give the best examples and analogies I can.

 

[Luke'sScreenName]

Those that think faulty seals can cause the main loader to drift (cylinders compressing,) and there are many here on TBN that believe this....I'd love to have a junk cylinder and 30 minutes and I would guarantee I could prove that it ain't possible.

How about faulty rod seals?
Pretty sure if those leak you'll get leak-down (and a puddle)

Maybe it would be more accurate to argue that internal cylinder leakage can't cause leak-down in such applications?

Nothing like a little obtuse obfuscation to help the discussion along... :drink:

 

[Tjdux]

How about faulty rod seals?
Pretty sure if those leak you'll get leak-down (and a puddle)

Maybe it would be more accurate to argue that internal cylinder leakage can't cause leak-down in such applications?

Nothing like a little obtuse obfuscation to help the discussion along... :drink:

Yeah a cylinder with poor seals will compress (especally with no regenerate pressure from the pump) no matter what. If the pressure can pass from one end to the other then with nothing to equalise (pump) it will fail (fall or drift)