Excavator Pump Parts A10VS063 Piston Pump Spare Parts Set Plate Retainer Plate Rexroth R902503255 Retain all piston shoes to stop them from detaching from the swash plate. While the cylinder block rotates fast under high pressure impact, springs push the cylinder block so piston shoes are pressed onto the swash plate inclined surface. The set plate encloses piston shoe tails to prevent outward escape, ensuring piston shoes continuously fit the swash plate friction surface and