Tractor Repair: Hyd, problem with tractor, shade tree mechanic, torque amplifier

Question
Arnie,
 I have a 1086 International Harvester farm tractor. This tractor was bought second hand and has a torque amplifier that I was told not to move the lever on as it did not work. (Don't know if this has anything to do with problem.) I noticed when going downhill bushogging, that the PTO would loose power to it, but as soon as I was going back uphill or on level ground, it was O'K. The tractor set for 4 or 5 months this last time, and when I went to use it, it would not untrack itself, it was like I was setting there with the clutch pedal pushed down, but it was up and the tractor should have been moving. I could see the tires tension up and relax, then all of the sudden it might take off and go 20 to 100 ft, stop and do it all over again.It's like riding a bucking bull) The power steering at this point does not work unless the tractor is moving, if it's just setting there and not moving (when it should be)you can just turn the steering wheel round and round with no response on the front end. While this is going on, I hear a high pitched noise, like a pump starving for fluid or air in the lines. The dip stick on the hydraulics shows it to be full. I am on the high side of 55 years old and think I'm a fair shade tree mechanic, but I'm not sure where to start. Any help would be greatly appreciated.

Answer
Hello,

  The power steering, brakes, and torque amplifier get their oil from a pump behind the multiple control valve on the left side of the clutch housing.  The 3 point hitch and remotes get their oil from another pump just in front of the rear axle housing.  The PTO has its own pump.  All 3 of these pumps are driven by a shaft that is splined into the pressure plate of the clutch which is bolted to the engine flywheel, so the shaft is turning anytime the engine is running, giving you live pto and hydraulics.  The splines on this shaft are notorious for wearing and stripping out where they go into the hub of the pressure plate.  If the splines are just starting to go, sometimes they will slip for a while and then grab for a little while and then slip again.  If the torque amplifier was good, the tractor would still move in the low position, because low is driven by a mechanical sprag clutch and does not need hydraulic pressure to engage.  Hi position is engaged by a hydraulically applied clutch pack, so if you lose hydraulics, it should still pull in low.  But because your TA is bad, low doesn't work either.  The splines slipping is what is causing the noise that you hear.  The tractor will have to be split behind the engine, and the shaft and pressure plate will have to be replaced.  It will be a good time to replace the clutch and oil seals while the tractor is already split.