tilt cylinder drops

[ytr1903]

Hi everyone. It has been awhile since I posted here, which is a testament to the reliability of my 743. Recently, though, I had to replace the seals in the tilt cylinder. The process went quickly and smoothly, but when done I discovered that the bucket would tilt quickly. This happens whether there is weight in the bucket or not. (Faster with weight) This problem was not there before replacing the seals, so I can only guess that it was due to something that I did during the seal renew. Any suggestions or solutions would be appreciated. Tom

 

[Tazza]

Does it leak down when you shut the machine off?

 

[ytr1903]

Does it leak down when you shut the machine off?

Hi Tazza, Sorry to be so slow on responding. The bucket tilts down after the engine is off as well as tilting down while the engine is running. It tilts down faster as weight in the bucket is increased. Tom

 

[Tazza]

Hi Tazza, Sorry to be so slow on responding. The bucket tilts down after the engine is off as well as tilting down while the engine is running. It tilts down faster as weight in the bucket is increased. Tom

It could be bad locd check seals, as you have pretty well eliminated the rams with the new seals.
I found that with the engine off, if you tilt the pedal back the bucket stops dropping, this indicates that is is the load checks.
Of the movement isn't really noticable when operating it, forget about it. But if you can sit in the cab and watch as the ram moves, it needs looking at.

 

[lswift]

It could be bad locd check seals, as you have pretty well eliminated the rams with the new seals.
I found that with the engine off, if you tilt the pedal back the bucket stops dropping, this indicates that is is the load checks.
Of the movement isn't really noticable when operating it, forget about it. But if you can sit in the cab and watch as the ram moves, it needs looking at.

This my first post. I have problem with the tilt cylinder dropping. The problem is worse with more weight. It occurs with engine on or off, hot or cold. If I curl bucket out so that skid steer is lifted and release the pedal, there no leakage and the skid steer remains lifted. I have tested the tilt cylinders by blocking them off and raising the boom. The bucket did not sink. After reconnecting the tilt cylinders, the bucket again dropped. Any ideas. I really don't want to remove spool valves. There are 1700 hours on the skid steer and everything else works well. -

 

[Tazza]

This my first post. I have problem with the tilt cylinder dropping. The problem is worse with more weight. It occurs with engine on or off, hot or cold. If I curl bucket out so that skid steer is lifted and release the pedal, there no leakage and the skid steer remains lifted. I have tested the tilt cylinders by blocking them off and raising the boom. The bucket did not sink. After reconnecting the tilt cylinders, the bucket again dropped. Any ideas. I really don't want to remove spool valves. There are 1700 hours on the skid steer and everything else works well. -

Load checks screw into the control block housing.
If you look at the control block, it's sort of in segments. You see a spool and in that same line is the hydraulic lines and load checks that screw into the valve body inline with the path of the spool. It is possible a load check here is bad. Some had Orings that break over time.

 

[lswift]

Load checks screw into the control block housing.
If you look at the control block, it's sort of in segments. You see a spool and in that same line is the hydraulic lines and load checks that screw into the valve body inline with the path of the spool. It is possible a load check here is bad. Some had Orings that break over time.

Thanks Tazza for response. I have removed the lift check valve and everything looks good. Also, I think the lift check works the same for curling and uncurling the bucket and there doesn't seem to be the same leakage when pressure is pushing bucket up. It only seems to leak when there is weight down on the cylinders. My manual suggests that the boom pressure relieve could be the problem. I can't see the connection. It also suggests that the O rings at the ends of the spool valve could be leaking. Do you think the control valve is a likely problem? Is it possible that the spool is not centering properly?

 

[Tazza]

Thanks Tazza for response. I have removed the lift check valve and everything looks good. Also, I think the lift check works the same for curling and uncurling the bucket and there doesn't seem to be the same leakage when pressure is pushing bucket up. It only seems to leak when there is weight down on the cylinders. My manual suggests that the boom pressure relieve could be the problem. I can't see the connection. It also suggests that the O rings at the ends of the spool valve could be leaking. Do you think the control valve is a likely problem? Is it possible that the spool is not centering properly?

I am not sure if the tilt cylinder has a relief or not, but worth looking to see if it's there or not though.
If the seals were bad on the spool, you would see the oil leaking out of the valve, it would take a lot of leakage for the bucket to drop.
One thing you can hopefully try is to load up the bucket, lift it up, shut down and tilt the pedal back, see if the cylinder drift stops or not.

 

[lswift]

I am not sure if the tilt cylinder has a relief or not, but worth looking to see if it's there or not though.
If the seals were bad on the spool, you would see the oil leaking out of the valve, it would take a lot of leakage for the bucket to drop.
One thing you can hopefully try is to load up the bucket, lift it up, shut down and tilt the pedal back, see if the cylinder drift stops or not.

The manual does not show a relief for the tilt cylinder. Also, the control valve is completely dry on the outside. I tried the test you suggested. The bucket continued to drift down unchanged as I tilted the pedal back. Do you think this means that the tilt cylinders may be leaking internally? I don't mind repacking the cylinders if that is the problem. - L

 

[Tazza]

The manual does not show a relief for the tilt cylinder. Also, the control valve is completely dry on the outside. I tried the test you suggested. The bucket continued to drift down unchanged as I tilted the pedal back. Do you think this means that the tilt cylinders may be leaking internally? I don't mind repacking the cylinders if that is the problem. - L

It's sounding like it is the seals.
I found that on a machine with bad load checks, when i moved the pedal back, it would stop moving.

 

[lswift]

It's sounding like it is the seals.
I found that on a machine with bad load checks, when i moved the pedal back, it would stop moving.

Thanks for your help. I'm assuming by "seals" you mean the seals in the tilt cylinders and not the control valve. I'm not sure that I understand why the cylinder would stop dropping when you curled the bucket up with engine off, but I'm mainly an auto mechanic and have little diesel and hydraulic experience. I think I'll go ahead and overhaul the two tilt cylinders and see what I have. Will report back. - L

 

[Tazza]

Thanks for your help. I'm assuming by "seals" you mean the seals in the tilt cylinders and not the control valve. I'm not sure that I understand why the cylinder would stop dropping when you curled the bucket up with engine off, but I'm mainly an auto mechanic and have little diesel and hydraulic experience. I think I'll go ahead and overhaul the two tilt cylinders and see what I have. Will report back. - L

Yes, the seals in the tilt cylinder(s) not the control block.
When tilting the pedal back with the machine off, it changes the location of the spool in the control block, blocking different holes in it, sort of by-passes the load checks, at least it did when i do it as a test.

 

[lswift]

Yes, the seals in the tilt cylinder(s) not the control block.
When tilting the pedal back with the machine off, it changes the location of the spool in the control block, blocking different holes in it, sort of by-passes the load checks, at least it did when i do it as a test.

Sadly, installation of seal kits in both tilt cylinders made absolutely no difference. The old seals did not look too bad and the cylinders seem free of obvious wear. I have put skid steer back into use and all other functions work well. One thing I notice is that it seems like the bucket drops more quickly for the first ten or twelve inches and then slows down. This could indicate that there is wear at one end of cylinder. I wish I had used a good inside micrometer to check for wear. Is uneven wear a common problem in hydraulic cylinders? Any other suggestions for possible causes of cylinder drop?

 

[jerry]

Sadly, installation of seal kits in both tilt cylinders made absolutely no difference. The old seals did not look too bad and the cylinders seem free of obvious wear. I have put skid steer back into use and all other functions work well. One thing I notice is that it seems like the bucket drops more quickly for the first ten or twelve inches and then slows down. This could indicate that there is wear at one end of cylinder. I wish I had used a good inside micrometer to check for wear. Is uneven wear a common problem in hydraulic cylinders? Any other suggestions for possible causes of cylinder drop?

The most positive way to check the tilt cylinder is to fill the bucket with weight while down then disconnect the lines and plug them and the ports on the cyl. If it droops when you lift it now it has to be bypassing internally. The droop speed changes because of the geometry between the cyl attaching point and the bucket.

 

[lswift]

The most positive way to check the tilt cylinder is to fill the bucket with weight while down then disconnect the lines and plug them and the ports on the cyl. If it droops when you lift it now it has to be bypassing internally. The droop speed changes because of the geometry between the cyl attaching point and the bucket.

I have the hydraulic line plugs and will repeat test of blocking off cylinders and observing droop. I did this test before I replaced cylinder seals and the droop was significantly improved. I am planning to do it again with bucket tilted at different angles to check droop with piston at different locations inside cylinder. My theory is that faster droop would indicate wear in cylinder. Do you think the changes in geometry that were mentioned are enough to make the rate of droop change significantly as the bucket uncurls. If so, would the droop be fastest fully curled and slow as the bucket uncurls? Honest to God! I just can't see what can cause the problem if it isn't one or both tilt cylinders. I'm going to test the cylinders again and if they check out good I'll have to look at control valve. Thanks for help.

 

[billrbg]

I have the hydraulic line plugs and will repeat test of blocking off cylinders and observing droop. I did this test before I replaced cylinder seals and the droop was significantly improved. I am planning to do it again with bucket tilted at different angles to check droop with piston at different locations inside cylinder. My theory is that faster droop would indicate wear in cylinder. Do you think the changes in geometry that were mentioned are enough to make the rate of droop change significantly as the bucket uncurls. If so, would the droop be fastest fully curled and slow as the bucket uncurls? Honest to God! I just can't see what can cause the problem if it isn't one or both tilt cylinders. I'm going to test the cylinders again and if they check out good I'll have to look at control valve. Thanks for help.

I'm getting confused here... now your are talking about TWO cylinders, but the "tilt" only has one, as you indicated at the beginning of this thread. Which cylinders did you put the new piston seals into, the tilt cylinder, in the middle behind the bucket, or the lift (arm) cylinders?

 

[lswift]

I'm getting confused here... now your are talking about TWO cylinders, but the "tilt" only has one, as you indicated at the beginning of this thread. Which cylinders did you put the new piston seals into, the tilt cylinder, in the middle behind the bucket, or the lift (arm) cylinders?

I have a New Holland lx665 which has two tilt cylinders, one on each end of bucket. They operate in tandem. I put seal kits in both cylinders. Sorry to be confusing.