john deere 755 hydrostatic problem

[stripercity]

my john deere 755 hydro is not working. if you play with the pedal long enough it will move for a bit and then stop. The pump is good cause everything else on the tractor works. I was told the valves might need cleaned out. has anyone else had this problem? it has a new filter and fluid so that can be ruled out. Id appreciate any help.

 

[kennyd]

The Hydrostatic tranny has it's own pump driven directly from the engine crankshaft, the other hydraulic work from a separate pump.

 

[prosperity]

it has a new filter and fluid so that can be ruled out.

Did this problem start before or after the fluid/filter change?

 

[crashz]

I'm no hydro expert, so I'll only go for the simple stuff.

The hydrostatic pump and hydraulic pump for the implements are totally different. So just because the loader or 3pt hitch lift properly has no bearing on the hydro drive pump or motor.

That being said, I'd check the pedals for free movement and anything possibly jammed into there causing only slight movement. Also check all linkages and adjustment for the pedals. Also fluid level. If all are good, it may be time to send it to the dealer or start studying the repair manual.

Another thing to look for is the pump pick-up screen. My 770 (gear tractor) has a seperate screen before the pump inlet and canister filter. Maybe your 755 has this on the hydro pump and it needs to be cleaned??

 

[JD755]

The hydro pedals have a couple lockout features that might be hanging up. Under the seat is a vertical rod with a white plastic tip that gets pushed down when the operator is on the seat. Less likely but possible also is the parking brake linkage that locks out the pedals.