Pistons can be found in reciprocating engines, pumps, compressors, and other mechanisms. Inserted into the cylinder and made gas-tight (similar to air-tight) by piston rings, a Piston’s primary job is to transfer force from ignited gas in the cylinder to a crankshaft. The crankshaft is then attached to an axle or another component to convert movement from the crankshaft to movement or force in the system. In other applications like pumps, instead of creating or causing the force, crankshafts will attach to pistons so they can use their motion to compress or expel fluid from a cylinder.
Related terms: combustion chamber, crank shaft, cylinder, dead centre, engine block, injector nozzle, spark plug