I may have discovered my curl issues on my tractor

[screamin400]

Mine has done it since day one.

 

[LD1]

Acceptable slip with engine running keeping the cylinders pressured should be almost unmeasurable over an hour or probably more in my opinion. Especially on a new machine.

Engine running does NOT keep the cylinders pressurized.

With curl, it could be valve, or cylinder, or a combination of both.

There are some test you can do.

1. This requires a floor jack. And personally I'd put a load on the forks to exaggerate the issue.

Put a load on, a foot or so off the ground, take some pressure off with the floor jack under the load. Now unhook the quick disconnects for the curl. Observe.

 

[Egon]

Whatever position the bucket is at the control valves must be closed for stable position. The tractor does not have to be running. For the position to change downwards there has to be fluid leaving the cylinder. Either a cylinder seal leaks, the control valve leaks or a PSV leaks or an external fitting leaks.

 

[LD1]

Whatever position the bucket is at the control valves must be closed for stable position. The tractor does not have to be running. For the position to change downwards there has to be fluid leaving the cylinder. Either a cylinder seal leaks, the control valve leaks or a PSV leaks or an external fitting leaks.

Yes on a lift cylinder.

Maybe I'm the one confused, but I though we were talking about curl cylinders? Where the bucket/forks want to dump.

(Drift caused by cylinders extending is different that drift caused by cylinders compressing).

 

[Tjdux]

I will admitt im not a full trained mechanic but i still.hold my ground that the cylinders shouldn't be drifting any measurable amount. I beleive thats the OPs question.

My experience growing up on a farm moving 1000s of big round hay bales (1000# approx) with a loader off fields that can be over half mile long and no drift with load on the curling forks.

Either the cylinders are leaking or the control levers are leaking or something. He needs to get it in and fixed while under warrenty.

 

[oldpilgrim]

The control valve is more complicated than a cylinder by magnitudes. I'd bet it's the problem.

 

[LD1]

It's a real simple test to determine which one is the culprit

 

[Egon]

Yes on a lift cylinder.

Maybe I'm the one confused, but I though we were talking about curl cylinders? Where the bucket/forks want to dump.

(Drift caused by cylinders extending is different that drift caused by cylinders compressing).

Don't matter. The hydraulics are a closed loop. The cylinder will move to the side of least pressure. If pressure is even the cylinder is static. So all you gotta do is look at places the fluid can leak by.

Hydraulic cylinder function is sorta universal. It could be reversed with flow points reversed and operate the same. Just leave the flow points as is and control function will be reversed. The only difference being one direction will have a total force that is greater than the other direction. Probably why most cylinders are positioned as they are.

 

[LD1]

Not sure what you meant by all of that.

Let me try to clarify (simplify)

On a typical tractor, the LIFT has cylinders that extend to lift, and retract to lower. Cylinders oriented like this WILL NOT drift, not even a fraction of an inch, as a result of a cylinder needing a rebuild. If cylinders are drifting in the retract direction....look elsewhere. You either have a leak which would leave an oil stain wherever you are parked, or it's leaking past the spool and your valve is worn out.

However, curl circuits (bad most backhoe booms) are just the opposite. Gravity acts to make the cylinder EXTEND. And if this drift is significant, it can be the cylinder, valve, or a leak.

So in summary:
Lift cylinder drift....one of two possibilities.
.......external leak. (Pretty obvious and easy to find)
.......valve. replacement is about the only fix as there are no "seals" in the valve on the spools.

Curl cylinders drift....three possibilities.
1. Leak, same as above.
2. Valve, same as above.
3. Cylinder worn out.

It could also be a combination of a worn valve and worn cylinder. Testing a cylinder is easy. Isolating weather the problem is the cylinder or the valve is easy.

 

[Egon]

Sounds interesting but I'm afraid I am limited to not understanding much of what goes on other than what the pressure is on each side of the cylinder piston which kinda may be an indication of which way the cylinder rod moves.