Hydraulic drift

[mazy]

I was recently moving some large old barn beams with pallet forks using my LA854 loader on my tractor and have run into a problem. I must have put too much strain on the hydraulic rollback/dump cylinders as they are no longer holding firm with a load on them. The loader rolls slightly forward and I need to constantly roll it back to keep it in position. Clearly some damage has been done, but before I make the dreaded phone call and have someone pick up the machine or charge an arm and a leg to repair on site, I am wondering what to do to trouble shoot the problem I am experiencing. There is no noticeable leaking of fluid so I am assuming damage is inside the cylinders. Any feedback would be tremendously appreciated.

 

[J_J]

You can check the piston seals by removing a hose from a port on the cyl and make the cyl extend or retract.

A good cyl will extend or retract and hold, and the relief will sound off, with no leakage. .

A worn or damaged piston seal will keep passing fluid as long as the lever is held.

You should be able to do the seals your self.

 

[mazy]

Will that permit air into the hydraulic line and if so will I need to bleed the air out?

 

[oldnslo]

Mazy,
Do you have quick disconnects on the lines to your loader? If yes lower the forks so they are resting on the ground. Place some weight on the forks and disconnect both hoses to the tilt function on your loader. Raise the load off the ground a few inches but so high that if the forks drift it dumps the load in an unsafe manner. Let the tractor sit and see if the forks drift or dump. If yes and their are no external leaks you have at least one cylinder with bad piston seals. If the forks do not drift your directional valve is leaking. If this problem just started it is possible that the linkage to the valve is binding preventing the spool from returning to center or the centering spring may have came loose.

Roy

 

[J_J]

If cable operated, could be binding cable.

 

[J_J]

Will that permit air into the hydraulic line and if so will I need to bleed the air out?

Air in hyd fluid is usually caused by suction leak or cavitating fluid.

Any air in the cyl or lines will self purge as you use the hyd system.

 

[mazy]

Thanks Roy for the feedback.Yes, it is a quick attach loader so I shoul be able to trace line back to hydraulic valve manifold and disconnect easily. I am guessing that when the tip of the pallet forks come into contact with an object when they are in a near fully dumped position, that there is a great deal of torque placed on them and something has to give. I have been using them for years, but just got busy working too fast and clearly put too much pressure on them when they were in a bad position. The machine only has 120 hours on it, but I am sure seals can break when too much force is applied. I have never taken apart a cylinder myself, but was watching a few videos of guys replacing seals over the weekend and it looks like it just takes some time and patience to get it done right. I just wish I could figure out which one has the bad seal, but will experiment with your technique and do what J.J. mentioned to see if I can figure out which one has the problem...although it could be both! Thanks for the suggestions Roy.

 

[J_J]

If the two cyl have a tee remove the supply to one hose and cap the tee. then retract or extend the cyl to see which one leaks.

If that one check out good, then switch the fittings to check the other cyl.

 

[oldnslo]

Mazy,
If you damaged the seals on one cylinder I would probably just rebuild them both. Logic says if one was pushed to the breaking point the other may be close behind.

Roy