Crankshaft

The central component of a reciprocating engine, a high-strength, alloy steel shaft with hardened and polished bearing surfaces that ride in bearings in the crankcase. Offset throws are formed on the crankshaft on which crankpins are ground and polished. Connecting rods, driven by the pistons, ride on the crankpins and change the in-and-out motion of the pistons into rotation of the crankshaft. The propeller of an airplane or the rotor system transmission of a helicopter is driven by the crankshaft.