There are a few scanned pages from the PT1845 Owners Manual and the Deutz Workshop Manual on the Maintenance page.
Let me describe this repair by quoting a TractorByNet Power-Trac forum thread I initiated on the subject.
I've been putting up with a slow hydraulic fluid leak for months now. Every now & then I would take a look around, decide it was a fitting on one of the many return lines to the tank and put off doing anything about it. They are really tough to reach and if I have to take one off, the tank has to be drained first. Procrastination rules! Until yesterday when out mowing and the leak got suddenly much worse. As my eye passed by the RPS valve on its way to visually check out the return hoses it was arrested by a fitting that looked bent. Bent? Gwan, how can that be? Well, it was bent alright. And leaking like a sieve.
When I took the hose off and the fitting out what I found was quite astonishing.
6/8/05 (651 hours) I had been noticing for quite some time, a year or so, that sometimes when I turned the steering wheel slowly to make a course correction the steering input would have no effect - the steering wheel would turn but the tractor continued on its merry way. It wasn't too troublesome - a quick jerk of the wheel and it would catch and steer fine for that correction. Often it would work just fine. Then suddenly the other day it got much much worse.
"Climb Stall" issue
There is no repair invloved here but I did want to record this bit of information. I had been having trouble climbing a 25 degree slope while roughcut mowing around the back side of TKJ's pond. There was plenty of traction but not quite enough wheel torque to make the climb. Forward motion would cease.
6/17/2002 Telcon: Terry Estep at Power Trac re stalling while trying to climb 25 degree slope behind TKJ's pond. He thinks it should climb 25 degrees ok though the 40 degree rating is for sideways mowing. Says it may climb better with PTO off to keep engine revs up. Check hydraulic pressure at air bleed port. It should read 260-280psi cold and 240-260psi hot at a fast idle. Low reading may indicate a scratched plate in the tram pump from not getting air all out on filter change.
7/1/2002 Gage reads 300+ at fast idle, 370+/- at full throttle cold, 280+/- at fast idle, 320+/- at full throttle hot.
7/18/2002 Checked TKJ's slopes more carefully and get 27 deg typical reading with 30 degree max (where it won't climb).
11/19/2002 Talked with Terry Estep: above pressures good. Real pump test is to check pressure under load. Up against a tree, hot, should see 240-260. If not call Terry to get wheel motor test procedure.
11/24/2002 Ran a test up against a tree. Tractor not fully warm: had been running maybe 15-20 minutes under light loads. Hydraulic tank warm to touch - weather in the 40s. At mid throttle and greater: pressure above 300 psi, dropped to 270 +/- as treadle increased. Pressure held there until sufficient treadle applied to pull RPMs down. Put up pressure on arm to keep front wheels from spinning. All 4 would turn very slowly, first one then another.
It looks like there is no hydraulic system problem but rather a design limitation. A little additional torque might be gained with heavier hydraulic oil in the system. After the fire rebuild I replaced the hydraulic oil with Kubota AW ISO VG 46. This seems to be slightly thinner than the original oil when hot and I may have lost a bit of torque. If I had it to do over I would consider 20W50 Mobil 1 synthetic as a hydraulic oil.