Excavator ran well until unit is reached normal operating temp, about 2 hours. Engine began to bog down when boom was activated, then bucked and track slowed. Suspect pump is not de-stroking (rear pump) and found front pump stuck in mid stroke during removal. Pulled pump and noticed forward pump was not at full stroke when viewed through pump suction, rear pump was at full stroke. when pump regulator end was loosened observe forward pump stroke go to full stroke (spring position). Pump regulator appears ok, all is clean, spools are free. Inspect swash plates and find some scoring, maybe explaining why forward pump was initially not at full stroke when pump was removed. The fact that the forward pump was not at full stroke when pulled but then popped to position when the bolts were loosened seems to be pointing to an issue with the clearance of the forward pump swash plate. Anyone know how this clearance is set?
Good day Often the hydraulics get condemned when the issue is with the motor.. Kind regards Uffex
uffex, Circuits that the rear pump provided flow to would bog down the engine when the relief lifted (after heat soak). Prior to heat soak this did not occur. Circuits that the front pump provided flow to became very slow and did not seem to bog the engine after this same heat soak period, i.e. when the bucket cylinder was held over relief. Front pump provides flow to the bucket and right track motor. Both became painfully slow, and did not bog the engine at all. The front pump being stuck in mid stroke when removed from the machine seems to indicate a pump problem and not an engine problem. Do you agree?
Good day Jerk Yes your explanation indicates a likely regulation issue I will dig out the schematic if I have one and come back. Kind regards Uffex
What did the cradle bearings look like .
Volvomad, I'm not sure what cradle bearing is referring to. The movable plates have no bearings on this pump.