overrunning clutch

device

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 1, 2026

Quick Summary

An overrunning clutch is a specialized device that transmits torque in only one direction. This allows the driven shaft of a machine to freewheel, meaning it can continue rotating even when the driving source stops.1

A common example is found on bicycles, where this type of clutch enables riders to coast without pedaling. In starter mechanisms, an overrunning clutch transmits the cranking effort to start an engine but disengages when the engine begins to drive the starter itself. Essentially, it permits a rotating member to turn freely under certain conditions but not others.12

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clutch
An overrunning clutch transmits torque in one direction only and permits the driven shaft of a machine to freewheel, or keep on rotating when the driver is stopped. On bicycles, such clutches permit the rider to coast without moving the pedals.
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An overrunning clutch transmits torque in one direction only and permits the driven shaft of a machine to freewheel, or keep on rotating when the driver is stopped. On bicycles, such clutches permit the rider to coast without moving the pedals.
Read More