JD 955 Compact Tractor lost all hydraulic power today

J_J · Nov 28, 2011

I believe your implement pump puts out about 7 GPM, at 2500 psi. The only thing I can think of with the hydro trans, and implement pump in common is the reservoir. You did check the level, right.

The Implement pump and associated hyd has their own relief in the FEL valve and in the 3pt.

I believe the hydro trans, has several reliefs in the transmission.

Hoopcoachd · Jan 5, 2012

OK - got something that I will check out this weekend - there may be a small pin that holds the u-joint from the engine to the hydraulic transmission...looks like a c-clip and you have to pull the floor board off to see it. makes sense b/c I have no PTO nor do I have hydraulics.

Mechanos · Jan 5, 2012

It's hard to keep up with this issue since you have 3 different threads on the same subject. The reason you do not have any PTO is because you do not have any hydraulic power from the implement pump. The PTO on the 955 is activated by a hydraulic clutch. No implement pump... no hydraulic pressure. No pressure... no clutch activation. No clutch activation... no PTO.

wdchyd · Jan 5, 2012

:confused2:........:confused2:

Hoopcoachd · Jan 6, 2012

I'm looking at the schematic and see your point - now, what are the possibilities? Broken input or output shaft? One reply notes that the couplings are splines and indicates that a sheared pin would not cause the problem. I will read the tech manual and see what I have to do to pull the shaft - can't see any solution except a broken shaft BUT hitting a 1.5 inch pine stump with flail blades shouldn't cause that type of damage. Since I can't do an MRI, I will just pull it and see. Thanks for your expertise and advice.

Mechanos · Jan 6, 2012

Work smarter... not harder. First thing I'd do is remove the implement pump off the rear of the transaxle. Then turn the engine driveshaft over by hand and have a helper look at the end of the shaft that drives the implement pump. If that shaft does not turn at a 1:1 ratio with the driveshaft, then something is broken. If the transaxle mainshaft is turning, then try to hold it in place with something and see if you can turn the driveshaft. If you can hold the transaxle mainshaft in place and still turn the driveshaft... something is broken.

It's not fun and pretty much a PITA in my opinion to pull the transmission on a 955. It's even much, much, much more work to pull the transaxle. I wouldn't begin to do either one without doing as much non-invasive diagnostics as possible.

I agree that hitting a small stump like that should not have cause this level of damage... unless a shaft was already cracked or weakened and hitting the stump was just enough to sound it's death knoll.

Good luck and be sure to let us know what you find out.