<Tr> <Td> </Td> <Td> This article does not cite any sources . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> Reciprocating motion, also called reciprocation, is a repetitive up - and - down or back - and - forth linear motion . It is found in a wide range of mechanisms, including reciprocating engines and pumps . The two opposite motions that comprise a single reciprocation cycle are called strokes . </P> <P> A crank can be used to convert circular motion into reciprocating motion, or conversely turn reciprocating motion into circular motion . </P> <P> For example, inside an internal combustion engine (a type of reciprocating engine), the expansion of burning fuel in the cylinders periodically pushes the piston down, which, through the connecting rod, turns the crankshaft . The continuing rotation of the crankshaft drives the piston back up, ready for the next cycle . The piston moves in a reciprocating motion, which is converted into circular motion of the crankshaft, which ultimately propels the vehicle or does other useful work . </P>

Converts linear motion of the pistons into rotary motion