Plain English Meaning

The long shaft inside the engine that turns the push-and-pull motion of the pistons into a spinning motion, which then drives the propeller.

Full Definition

The main rotating shaft of a piston engine that converts the up-and-down (reciprocating) motion of the pistons into rotational motion. In an aircraft engine, the crankshaft transmits this rotation to the propeller, either directly or through a reduction gear.

Context Anchor

Seen in engine and propeller discussions, especially when learning how a piston engine turns fuel-burning power into propeller rotation.

Derivation

From 'crank' (a bent arm or used to turn something) and 'shaft' (a long rotating rod). The shaft has , or 'throws,' built into it that the pistons push on, the same way you'd turn a .