Need Some Hydraulic Troubleshooting Help

[redgoldwing]

Hi! I've got a Kubota L3750 tractor with a Westendorf TA25 Front End Loader. My problem is that the loader bucket slowly sinks from the raised position to the ground (the curl of the bucket maintains whatever angle it was left at).

I'm new to using farm equipment so I need some real basic help on troubleshooting this problem.

Thanks,
Bill Campbell
Pink Ribbon Farm
Oxford, PA

 

[J_J]

Check the valve lever centering springs.

Cyl seals might be worn out.

Valve spool might be leaking.

 

[redgoldwing]

J. J. Thanks. You've told me what to check but, as I said, I need basic help. How do I check these items?

Thanks,
Bill Campbell
Pink Ribbon Farm
Oxford, PA

 

[allenr]

Common to every loader I've had experience with.

I wouldn't worry too much about it.

 

[oldnslo]

Hi! I've got a Kubota L3750 tractor with a Westendorf TA25 Front End Loader. My problem is that the loader bucket slowly sinks from the raised position to the ground (the curl of the bucket maintains whatever angle it was left at).

I'm new to using farm equipment so I need some real basic help on troubleshooting this problem.

Thanks,
Bill Campbell
Pink Ribbon Farm
Oxford, PA

Bill,
how fast does it drop? several inches per second or inch a minute, inch per hour, etc..

Slow leak down or inch per hour is not unusual depending age and condition of equipment.

Faster leak down a simple test with the engine off. VERY Slowly move the lever a small amount like you are trying to raise the FEL. IF you can actually see the directional valve watch the spool move. Move it 1/32 of an inch and hold it there. Did the speed of the loader change? Move it the opposite direction like you are lowering the FEL a 1/32 of an inch. Does the speed change? If it gets slower when moving it one direction or the other this is an idication that your spool may not be returning to center.

BEFORE doing any of the following fully lower the FEL.

First I would check all the linkage from the control lever to the valve to make sure nothing is binding.

Can you post some pictures of the directional valve.

Most valves have the centering springs on the oposite end from the control lever. These are usually accessed by removing a cover. These covers usually are held on with 2 or more screws. If you are comfortable doing this start removing the screws. Does it feel like there is spring tension pushing the cover off? If yes be ready to catch parts as you finish removing the screws. No parts should fly out but..... **it happens. Look for twigs, pebbles, soy beans,(mice) etc in this housing. Clean it up and reinstall the cover.

On every FEL I have seen the cylinders extend to lift and retract to lower so the cylinder seals are not an issue. Cylinder can't retract unless there is an external leak.

Roy

 

[J_J]

If you were to lift the bucket in the air, and shut off the engine, how fast will the bucket drop?
Will it drop to the ground in 24 hrs?

With the engine running, and bucket about midway, does the lift arms descend on their own?

One postive check to eliminate the valve is to add a needle valve in the A work port. This should be the hose feeding the cyl base end port. So raise the lift arms in the air and close off the needle valve, If the cyl are good, this should lock the cyl in place. If the arms drift down, that means that the cyl piston seals are leaking. Just one of the seals can leak and the cyl will not hold. You can determine which cyl is leaking, by using the same needle valve on just one cyl.

For a valve to be considered bad as far as holding the pressure, there is a fluid drops per minute rating . Each manufacturer has there own limits, but it is what you think is not acceptable, that is important.

Roy,

I don't understand your last paragraph. If your seals are leaking, and you have a force pushing or pulling, the fluid will transfer to the other side of the piston to a certain point. The base side of the piston has more fluid than the rod side.

 

[oldnslo]

Roy,

I don't understand your last paragraph. If your seals are leaking, and you have a force pushing or pulling, the fluid will transfer to the other side of the piston to a certain point. The base side of the piston has more fluid than the rod side.

JJ,
Based on the following assumptions the cylinder will move very little or not at all with bad seals.

1) Cylinder is double acting and full of oil.
2) Load is in the direction of forcing the cylinders to retract.
3) No external leakage path from either cylinder port.

Reason being that under these conditions there is more volume in cap end than there is in the rod end. Oil does not compress so there is no room for the oil to transfer from the cap end to the rod end. Cylinder will move until the pressure is equal at both ports and then stop.

Does this make sense?

Roy

 

[redgoldwing]

Sorry for not replying sooner, I've been out of town. The bucket lowers several inches an hour. If I leave the bucket up at about 5' off the ground overnight, in the morning it's on the ground. I'll work on getting a picture to post of the control valve.

Thanks,
Bill Campbell
Pink Ribbon Farm
Oxford, PA

 

[redgoldwing]

Sorry for not replying sooner, I've been out of town. The bucket lowers several inches an hour. If I leave the bucket up at about 5' off the ground overnight, in the morning it's on the ground. I'll have to pick up a needle valve to perform the test you recommend.

Thanks,
Bill Campbell
Pink Ribbon Farm
Oxford, PA

 

[J_J]

After you have installed the needle valves, raise the lift arms about 5 ft, and close off the valve, The only way the cyl can descend is if the seals are leaking, and with the fluid closed off to the cyl, the cyl will try and equalize the pressure internally. If there is a load, it should fall faster.

You can do this with yur tilt cyl also.