Hydrostatic power loss

[trevorcoe]

Case 40XT hydrostatic weak transmission drive. Help needed. Problems are: very weak drive even while cold in both directions, both sides. Sauer Danfoss series M91 46841 tandem pump. Oil level OK. Changed canister transmission filter and cleaned tank suction filter. Replaced oil, 10w 30 engine oil as specified. Charge pressure 200psi rising to 300psi at full revs. Linkages all ok. Almost no pressure at servo heads when in drive position. Removed pumps and disassembled. Charge pump looks very good. Slight nick in large o ring. Cylinder blocks, pistons, swash plate, valve plate, all look virtually new. Charge pressure relief valve appears to be good, hence pressure. Servo piston rings good. Bypass valves seated ok. Hi pressure / check valves seem good. Reassemble, fitting new o rings to charge pump, no difference!! Appears not to be actuating the servo. Disconnected brake hose to eliminate pressure loss there, no difference. What next!!! Any help or ideas appreciated. Trev.

 

[billrbg]

You might be better served posting this in the Case forum...