crank

An axis bent through one or more right angles; it is used to transmit motion or convert reciprocating (backwards-and-forwards or up-and-down) movement into rotary movement, or vice versa.

Although similar devices may have been employed in antiquity and as early as the 1st century in China and the 8th century in Europe, the earliest recorded use of a crank in a water-raising machine is by Arab mathematician al-Jazari in the 12th century. Not until the 15th century, however, did the crank become fully assimilated into developing European technology.