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Morning everyone,

So was hauling a trailer around the yard with my 2" receiver that is on my loader and noticed that the weight was dropping and I had to keep lifting the load.

So I took everything off and raised the loader up with just the forks on and with in a minute, I began seeing the loader begin to loose is height and drop.

Took it into the john deere dealer and they said it was an internal seal leak on the hydraulic cylinder (the left curl cylinder). So they replaced it. Not sure what they would have charged since it was still under warranty.

It made me wonder, what would cause a an internal seal leak. Do you think I am working it too hard?

I do have a trenching bucket for the front which is wonderful digging out small stumps. What that have caused an internal seal leak?

Looking for thoughts or additional questions.

Don
 

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Seal

Morning everyone,

So was hauling a trailer around the yard with my 2" receiver that is on my loader and noticed that the weight was dropping and I had to keep lifting the load.

So I took everything off and raised the loader up with just the forks on and with in a minute, I began seeing the loader begin to loose is height and drop.

Took it into the john deere dealer and they said it was an internal seal leak on the hydraulic cylinder (the left curl cylinder). So they replaced it. Not sure what they would have charged since it was still under warranty.

It made me wonder, what would cause a an internal seal leak. Do you think I am working it too hard?

I do have a trenching bucket for the front which is wonderful digging out small stumps. What that have caused an internal seal leak?

Looking for thoughts or additional questions.

Don
Any number of things could cause a seal to start leaking. Here's a partial list in no particular order:

  • Bad seal as manufactured
  • Seal was cut when installed. It only takes a little nick with hydraulic pressures.
  • Slight roughness in the internal walls of the cylinder. Over time this degrades the seal.
  • Improper hydraulic fluid that reacts with the seal. Almost certainly not your problem but it is a problem with older/used equipment.
  • Sudden shock loading of the cylnder. A steady pressure usually just opens the relief valve but a shock load can blow the seal. Think carrying a heavy load and suddenly dropping a wheel into a hole.
  • Plain old wear. Again, probably not your issue but all seals will eventually leak if used enough.
Treefarmer
 

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Morning everyone,

So was hauling a trailer around the yard with my 2" receiver that is on my loader and noticed that the weight was dropping and I had to keep lifting the load.

So I took everything off and raised the loader up with just the forks on and with in a minute, I began seeing the loader begin to loose is height and drop.

Took it into the john deere dealer and they said it was an internal seal leak on the hydraulic cylinder (the left curl cylinder). So they replaced it. Not sure what they would have charged since it was still under warranty.

It made me wonder, what would cause a an internal seal leak. Do you think I am working it too hard?

I do have a trenching bucket for the front which is wonderful digging out small stumps. What that have caused an internal seal leak?

Looking for thoughts or additional questions.

Don
First, it must be said, an FEL leaking down is normal and it isn't always caused by internal seal leaks. The normal leaking down is caused by normal internal leakage that occurs in the SCV. No SCV is so tight that no oil can leak by the spool internally.

Now, leak down of the bucket roll is not as noticeable normally, unless the bucket is loaded, which yours was loaded with your receiver.

So, the only way to keep a loaded cylinder from retracting is to install load check valves (counterbalance valves) on the cylinders. These valves lock the oil in the cylinder until retract pressure is applied.

Now, were the internal seals in your left bucket roll cylinder actually bad. It might have been. Assuming your JD dealer knew how to test it, we will assume it was bad.

Question, does the bucket roll hold now?

So, assuming your one bucket roll cylinder had leaking seals, your question is why? Well, you said you have a trenching shovel that attaches over the bucket cutting edge, indicating this may be the reason for the internal seal leak. Could it be, absolutely!!!!!!!

Anytime you apply leverage force to the FEL lift or bucket roll, you can cause extreme pressure internally in the bucket roll or FEL lift cylinders. This leverage would be applied when you roll the bucket forward, apply down pressure on the trenching shovel, and then propel forward or reverse levering the shovel. This propelling forward and/or reverse applies leverage forces to the bucket roll and/or FEL lift cylinders which causes the internal pressures in the cylinders to exceed the pressure rating for the cylinder, even to the extend of blowing a cylinder up or a hose off.

The reason this extreme pressure can occur is, there are no port reliefs on the FEL hydraulic circuits. The only relief on the FEL hydraulic system is on the inlet side of the SCV so this relief prevents over pressuring caused by the system on the tractor when using the FEL the way it was designed to be used, E.g. lifting, but will not prevent over-pressuring caused by leverage forces caused by the operator.

Bottom line, FEL's are not designed for leverage types of work which is what happens when you use attachments like bucket shovels or using the tips of forks to lever something out like stumps, rocks, small plants, etc.

If you use you bucket shovel, or the tips of forks, or even the edge of the bucket to lever something, when you engage the bucket edge, bucket shovel, tips of forks, etc., and apply force by propelling forward or backward, hold the SCV lever in a multiple engaged position so the bucket roll up and FEL down are connected to the inlet relief. This will connect the SCV relief to the circuits and prevent over-pressuring of the cylinders. Now, you will probably no like the results because the minimizing of the pressure will result in much less leverage force being able to be applied to the fork tips or bucket shovel, but it will save you tractor!!!! :bigthumb: Just sayin!!!!
 

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I will add a couple things to Treefarmers excellent list.
Piston seals, O-rings and rod wipers are made from rubber or plastic polymers and are mass produced.
They rely on resiliency, proper fit and correct surface texture (micro finish) to function or last to designed operating life.
Excess heat or fluid contamination can also shorten lifespan.
Several times where I work I have purchased small cylinders that leaked past the piston seals because they were assembled a long time ago and sat on the shelf before selling.
Larger construction equipment will have more expensive piston seal construction that has extra grooves for more seals and rubber back up rings under the seals designed to keep force on the seals against the cylinder wall and also polymer bands to keep the piston centered and straight in the bore.
Unfortunately we will not get all that on these small tractors.
With use all cylinders will need "renewed" eventually.
 

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Discussion Starter #5
Tree farmer, Ray, and Jeff, thanks for your responses. Very interesting reading.

My fear is reading Ray's response where i may have put to much pressure with the trenching bucket which of course I love :( because of the trenching and digging it can do.

For the last paragraph mentioned by Ray "If you use you bucket shovel, or the tips of forks, or even the edge of the bucket to lever something, when you engage the bucket edge, bucket shovel, tips of forks, etc., and apply force by propelling forward or backward, hold the SCV lever in a multiple engaged position so the bucket roll up and FEL down are connected to the inlet relief. This will connect the SCV relief to the circuits and prevent over-pressuring of the cylinders." I may need to master that better.

Again, everyone's feedback was apprciated.


Thanks! :bigthumb:
 

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Tree farmer, Ray, and Jeff, thanks for your responses. Very interesting reading.

My fear is reading Ray's response where i may have put to much pressure with the trenching bucket which of course I love :( because of the trenching and digging it can do.

For the last paragraph mentioned by Ray "If you use you bucket shovel, or the tips of forks, or even the edge of the bucket to lever something, when you engage the bucket edge, bucket shovel, tips of forks, etc., and apply force by propelling forward or backward, hold the SCV lever in a multiple engaged position so the bucket roll up and FEL down are connected to the inlet relief. This will connect the SCV relief to the circuits and prevent over-pressuring of the cylinders." I may need to master that better.

Again, everyone's feedback was apprciated.


Thanks! :bigthumb:
There have been several posts on GTT over the last several years concerning FEL cylinders failing and/or hoses blowing off. I will say this, hydraulic cylinders and hydraulic hoses don't fail that easily under normal use. In fact, they are both down right pretty reliable.

9 times out of 10, if a cylinder fails or a hose blows, the cylinder or hose was over pressure by some external force applied to it or the hose was worn due to rubbing something.

When you apply leverage forces to the FEL, the word of the day is use caution or you will break something. Bucket shovels look like they are nice attachment but they must be used carefully.
 
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