crank (mechanism)

A crank is a bent portion of an axle, or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it; also used to change circular into reciprocating motion, or reciprocating into circular motion.One application is human-powered turning of the axle. Often there is a bar perpendicular to the other end of the arm, often with a freely rotatable handle on it to hold in the hand, or in the case of operation by a foot (usually with a second arm for the other foot), with a freely rotatable pedal. Familiar examples include:using a hand:manual pencil sharpenerfishing reel and other reels for cables, wires, ropes, etc.train windowmanually operated car windowusing feet:the crankset that drives a bicycle via the pedals.human-powered sewing machine
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