JD 4300 HST rock shaft quit

[pat32rf]

Not sure if this is a hydraulic problem or mechanical. Owned the tractor since new, about 6000 hrs on it.
Today I had the splitter on the 3pth with the splitter down on the ground. Easy splitting wood. At one point things seemed to momentary "lock up" and when I went to lift the splitter to clear the pile of split wood, nothing happened. The tractor was running about 1500rpm and I thought that a QD fitting had popped so I shut things down. Checked the fittings and restarted. The 3pth handle was in the up position and the splitter went up. I lowered it back to the ground and split for another 5-10 minutes and quit for the day. When I went to raise the splitter nothing happened. No sound of anything loading down or hoses getting stiff. The splitter was connected to the power beyond that is used for my hoe. It still splits fine, the FEL works as always, but it feels like the 3pth control handle is no longer connected.
Once I unhooked the splitter I could manually lift the 3pth, but it would fall right back down, no matter where the control was set.
Can't see a relief valve being stuck open as the splitter was sitting on the ground while being used but where would I look?

 

[dfkrug]

Hmm. Sounds like a position control valve problem. All this is under the seat, and I hope
you have a service manual.

 

[pat32rf]

Yep! It was a problem with the control valve. Seems that the metal filter element in the power beyond line had blown the bottom out and it wound up in the control valve. The hard part was removing the seat, transmission linkage, etc. Once I got the valve cover off I had to get those three metric allen cap screws out. Found a key that fit but when it came time to re-assemble I took an old bit from a hex screwdriver set, ground just a bit off each side and found it was much easier to use to start the cap screws.
An hour later I had all the linkage back on and my neighbour helped lift the seat into place.
Tomorrow we will be cutting basswood and poplar for pulp and maple for next years firewood.

 

[tonhon]

Good morning Sir, I am having the exact same problem with my 4300. When you got the position control valve open did you find the piece of screen that came from the filter? I am about to start disconnecting park brake and other linkage to access the valve. Also is there a gasket for the control valve cover? Thanks, Tony