Crank (mechanism)

A crank is a simple machine. Is a wheel and axle, with a one-sided lever.

• With a staff as a handle for rotating a shaft, the crank gives a hand crank. Also typical are the crank arms with screwed pedals a bicycle ( pedal crank ).
• A one-sided, attached to a machine shaft lever with hub and crank pin. These L- shaped bent lever assembly can exert a torque by force to a shaft, the crank pin can attack another simple machine, such as a rod at the crankshaft, the typical drive element of a steam engine and a motor, the rod transfers the force of the piston.

• Vices for some a threaded spindle by means of a crank moves, whereby the position of a jaw can be changed.

Other applications include the winch or the crank mechanism.

History

Remains of a Roman crank mill from the late 2nd century AD were excavated in the Bavarian Aschheim; using the 40 cm long iron crank was manually driven through a gear train of the millstone. Another Roman crank was found in Augusta Raurica ( Switzerland ). The 82.5 cm long piece of iron has a 15 cm long handle and is due to reach 250 AD in the ground. Its exact function is still unknown.

The depicted on the sarcophagus of Marcus Aurelius water-powered sawmill Ammianos in Roman times Hierapolis based in their function also on the knowledge and use of a crank. The same is true for two other late antique sawmill in Ephesus and Gerasa.