The piston assembly is the main part of the hydraulic end of the mud pump. The discharge pressure of the mud pump is generated by the reciprocating linear motion of the piston assembly in the cylinder sleeve. Piston small-pressure, low flow; The piston is large -- the pressure is small, the flow is large. The use of public and British pistons for metric pumps and imperial pumps. It is commonly used in φ 170, φ 160, φ 150 and 6 ′ ′, 6-1/2 ′ ′, 7 ′ ′ and so on. Metric pumps F800, F1000, F1300, F1600 piston general purpose, F500 piston inner hole is smaller than other models piston. The piston of the imperial pump F500-F1600 is universal. Metric pump F500 piston inner hole is φ 25.4; The inner hole of the F800-1300 piston is φ 42 and the inner hole of the imperial piston is φ 38.1. Material: Piston core 42CrMo; Rubber or polyurethane.