Komatsu PC400-6 PC450-6 PC300-6 PC350-6 Excavator Hydraulic Pump 708-2G-00191 708-2H-00350 708-2H-00130 Main Piston Pump

Komatsu PC400-6 Hydraulic Main Piston Pump - A robust, fully mechanical control system designed for heavy-duty mining and earthmoving operations with high reliability and automatic displacement adjustment.

This main pump assembly is directly driven by engine flywheel. It adopts fully mechanical control and automatically adjusts pump displacement according to load. Simple structure with high reliability, widely used for heavy-duty mining and earthmoving operations.

• Weak movement when hot, acceptable performance when cold - Wear of pistons and valve plate reduces volumetric efficiency and causes high-pressure internal leakage. Hydraulic oil contamination is the primary trigger.
• Engine lugging & speed drop - Misadjustment or stuck spool of PC power valve; EPC solenoid malfunction, pump displacement cannot be reduced, absorbed power exceeds engine output.
• Slow movement of whole machine - Clogged or damaged coil of EPC solenoid valve; stuck LS valve spool; worn internal pump parts leading to insufficient flow.
• Abnormal noise & vibration - Blocked suction filter, air entering suction pipe causing cavitation; damaged pump bearing, broken piston & shoe.
• Large case drain flow - Internal pump wear causes high-pressure oil internal leakage, which flows out from pump case drain port.