The cylinder piston assembly serves the purpose of transmitting force from the expanding gas in the cylinder to the crankshaft in an engine. For the goal of compressing or ejecting the fluid in the cylinder, the function is reversed in a pump, and force is transferred from the crankshaft to the piston. By transferring the force produced by an expanding gas in the cylinder to the crankshaft, which in turn gives the flywheel rotational momentum, pistons work. Cylinder piston assembly is part of a piston-cylinder system used to shift a load over a lengthy stroke.