I have a 1976? JD 310A model serial # 310AD 263812T. All hydraulic functions work. Forward and reverse work. Low range will push a tree over however high range it won’t pull itself up any type of grade. I do have a service manual ( TM 1158 ) and I have read it several times. System pressure should be 155-165 and I had 40. The suction screen was clean and I changed the hydraulic filters. I added 6 little washers to the pressure regulator valve and pressure went up to 65. Still not enough so I took it all apart andI do not see anything obviously wrong. The clutches and transmission oil pump and the valves in the valve body all look good. The clutch packs did have what appears to be a lot of clearance. Also I do see grayish residue in the oil and I wonder if that might have come from the brakes? I am scratching my head and I wonder if it could be something as simple as a sticking valve. Does anyone have any idea what I should check next? Thanks Nathan
Clutch linkage cross shaft roll pin tight?
I think so? I will check that tonight after work. This could hold the control valve open and allow oil to return to the sump? It would be like the inching pedal was partially depressed? I really hope that’s it! Thanks
Sorry about the delay in update, the cross shaft was tight however the linkage was bent and out of adjustment. I have it all back together and used it for about 8 hours and everything works great.