Excavator Parts AP2D36 Cylinder Block&Valve Plate 2.412-00125 For Hydraulic Pump Parts Adjust swash plate position and alter pump displacement Connected mechanically with the swash plate, the servo piston creates linear reciprocating movement under pilot pressure to adjust swash plate inclined angle: A bigger swash plate angle produces larger pump displacement and higher flow output. A smaller swash plate angle produces smaller pump displacement and lower flow output.