Crank -

A is a fundamental mechanical component—an arm attached at a right angle to a rotating shaft—used to convert circular motion into reciprocating (back-and-forth) motion, or vice versa. It is a cornerstone of mechanical engineering used to manually or mechanically turn axles, powered by either human effort or engines.

Cranks can be powered by hand (e.g., a winch) or foot (e.g., a bicycle pedal). 2. Key Examples & Applications

Here is a detailed write-up on the mechanism and applications of a crank. 1.