PSVL-54 Hydraulic Pump Swash Plate PSVL-54 Piston Pump Cam Rocker Excavator Pump Parts The swash plate is a key internal part for excavator main pumps. It stays static while cylinder block rotates; piston shoes slide on its surface. Functions Piston shoes bear against swash‑plate face. Swash‑plate inclination converts cylinder‑block rotary motion into pistons’ reciprocating linear motion for oil suction and pressure delivery. Pump displacement varies with swash‑plate