Excavator Pump Parts PSVL-54 Valve Plate RD20169040 Excavator Parts Flow Distribution & Commutation: As the cylinder block rotates, each plunger chamber is automatically alternately connected to the high-pressure and low-pressure oil ports to complete oil suction and discharge, replacing a separate directional valve. Sealing & Isolation: Forms an oil film friction pair with the end face of the cylinder block, isolates high and low pressure chambers, and prevents internal