Piston and Piston Rings - Part of combustion engine:

Piston: The piston reciprocates within cylinder and transmits force exerted by expanding gases to crank by means of connecting rod. The piston is machined accurately to running fit in the cylinder bore and is provided with the several grooves in which the piston rings are fitted.

Piston Rings: Piston is equipped with the piston rings to provide good sealing between the valves of cylinder and piston. The rings are installed in grooves in piston. The rings are of 2 types a) Compression rings b) Oil control ring.