Model B pto hydraulic problem

Sorry this is so wordy, but I wanted to explain what I was doing when the problem occured

While brushogging today I had to run the tractor at slow rpm's because it was REALLY ROUGH ground in some areas. I was holding the mower deck up in the air so it wouldn't bog down the engine in the extreme rough spots. Hind site, this probably was not the best idea. The last time I went to lower the brush hog back down, it would not lower. It was suspended off the ground. It was stuck in the up position. I got off the tractor, turned the engine off and released the pto. And cycled the lift lever several times thru the up, center, and down positions. Finally, after about 5-10times of this the brush hog lowered to flat on the ground. When I started the tractor back up, and engaged the pto. Is when it really started acting funny.

Well now the hydraulics are messed up. Here is what it is doing.

Normal operation is to pull the lever back to raise the 3pt arms, let go of the lever ( it will move to the center position) and it will maintain the 3pt arms at the current hieght, and push the lever down to allow the 3pt arms to lower.

Here is what it is doing now.

Pull the lever back--it will maintain the 3pt arms at the current hieght ( like it is supposed to do when releasing the lever to the center position)
Release the lever ( goes to the center position) the 3pt arms will drop (like it is supposed to do when pushing down on the lever)
Push down on lever--the 3pt arms raise ( like it is supposed to do when you pull the lever back). It does NOT have the lifting capability that it HAD when it was working properly. It will not lift the brush hog off the ground now. it will raise the front the the brush hog, but will NOT raise the rear wheel off the ground.


After reading over my shop manuals (most detailed was IT manual AC-11 pages 88-89) I've come up with 2 possible problems:

1> Is this how the "gumming up" that the shop manual talks about as being the usual culprit for hydraulic failure presents itself??

2> Is it possible the "control shaft" (#13 on page 88.) could have rotated inside the pump??

Thanks for any input you might have on this, I'm pretty much stumped.

Blessings,

Update on problem:

I went out and played around with the pump a little tonight. I started the tractor, engaged the PTO. Then I grabbed a hold of the control shaft that is visible and turned it with a pair of pliers.

As I turned the contol shaft the 3pt would respond. Either raising or lowering, but never really maintaining a hold position. This was all done without the use of the lever. As I would turn the control shaft, it would go from a slow raise, to a strong raise, then eventually as I turned it further it would allow the 3pt to lower.

Any thoughts???? Should I be able to turn the control shaft like this??? Is that the problem???? Any thoughts on a fix???

Blessings,

Additional info:

I figured out that if I keep the 2 tabs that open up on the cotter pin straight up with the lever in the lift position, It raise correctly. If the open ends of the cotter pin rotates to the rear of the tractor approx 45degrees in the hold position, the 3pt will hold, and if the open ends of the cotter pin rotate 90degrees to the rear in the lowering position, the 3pt will lower.

Seems like there is a problem with the control shaft staying in the correct orientation with the control plate.

Does anyone know how the control shaft hooks on to the control plate??

Blessings,

I believe the shaft is pinned to the plate. Sounds like the pin has sheared off.