Hi everyone, i have a problem with my excavator Sumitomo LS2800FJ2 main hydraulic pump. I have the Linkbelt LS2800C workshop manual but there isn't much about troubleshooting the pumps. I wonder if anyone has the manual for the hydraulic pump by uchida hydraulics KRJ3051? I need to set the flow rate. I did check the pump pressure, pump1 is maxed out at 320bar and pump2 is maxed out at 260bar. Setting anything above would bog down the engine. For pump1 the pressure would rise to 280bar and there's a delay the slowly creeps up to 320bar. For pump2 before adjustment it would maxed out at 220bar only, after adjustment it would go to 260bar max. In the manual it says the correct relief pressure should be 345bar. When comparing the tracks, one side is escpecially slower the the other. Should I change the relief valves first? or should I go straight to change the block and plungers of the pump? Any suggestions? the machine is slow moving now. Thanks! Jerry
According to my information, this should also equal a Case 9030a. Maybe you can verify this. If you have a bad pump, you will have multiple issues. Top pump controls boom, bucket, auxiliary, and RH travel. Bottom pump controls swing, arm and LH travel. Usually when you have a pump starting to fail, you will have brass in the reliefs in the main control valve. Its a fairly quick check to remove the reliefs and inspect.
Thanks for the tip! I have disassembled the main pump, plunger on the left pump had 1 broken ring, plungers on the right had 5 broken rings, and the regulator spool is stuck. All the other parts looks good, and already got the new replacement parts. Now waiting for assembly!