843h fella buncher drive issues

[chris allen]

Our cutter operations are fine other than drive function. When it gets to opperateing temp it starts to have drive issues an want back up or pull a hill. It’s got nearly 17000 hrs on it an serial number is 882239. Hooked a gauge to hystat test port this morning while it was cool an pressure was from 2000 to 4000 psi while driveing forward an reverse was kinda bouncing around Didn’t get to run long enuff to get it to act up an see what pressures were then. An for a long time now sometimes when parked it creeps backwards on its on without touching pedals. Filters look clean too

 

[Tones]

My guess, it's time to reseal the centre swivel joint. Thats where oil can bypass.

 

[Hallback]

^^THIS^^
Timbcos are notorious for this also.

 

[chris allen]

Just outta curiosity but I’m unaware of the center section in a cutter, I’m familiar with the center section valves on excavators an log loaders. But with my cutter being hystat drive isn’t just an accessory drive on rear of motor that drives the main pumps an hystat drive pump then from there to drive motors? Not sure of a center section on a cutter

 

[Tones]

Sorry, my mistake. I should have checked what the machine was, took it was a harvester with a fella buncher head.

 

[natemc]

Just checking the stall pressure for a hydrostatic drive will only give you part of the story. Than looking at it while driving gives even less.
17000 hours on the drive motor. You should flow the case drains and than start at the beginning of a drive setup if they pass within spec.
Very possible you could also have a pilot issue at the pedal if this machine has a pilot pedal instead of a wired pedal. Very often these are overlooked. But if I had to guess. The pump is needing the control section resealed