Operation of a reciprocating pump - continued.

c. A connecting rod connects the eccentric to a crosshead. As the eccentric goes through its circular motion, the crosshead moves to and fro, This is how circular motion of motor is converted into lateral motion. The pump piston is connected to the crosshead with a shaft. The crosshead's lateral motion is used to drive the pump piston. The pump piston moves forward and backward in the cylinder.

d. The right side of this sketch shows a pump. The pump is provided with suction and discharge ports. As the piston moves it sucks in liquid from the suction side, and pressurizes it to force it out through the discharge ports.