Since they transfer torque in one direction and spin freely in the other, these clutches are useful in applications where you don’t want motion to reverse, such as in backstopping, indexing, and overrunning. For example, they can be used to prevent a conveyor from reversing direction. They’re through-shaft clutches, so they regulate torque transmission between a drive shaft and a mounted component such as a pulley, sprocket, or gear.

When choosing a clutch, consider how much torque you need to transfer. Roller clutches are best for low- to medium-torque transfer in overrunning and indexing applications. Sprag clutches handle higher torque than roller clutches because they have more contact points. This makes them best for backstopping applications.

You should also consider how the clutch will attach to your mounted component. Clutches with a keyed hub let you slip on your component. Clutches without a hub have a precision ground outer race, so they can be press fit directly into a component and positioned anywhere along the length of your shaft. They also have mounting holes on their face you can use to secure your component or an anti-rotation device, such as a torque arm, for a different backstopping setup.

Clutches that mount to shafts with set screws bite into your shaft when tightened to hold it. Clutches that mount to shafts with a slip fit must be secured with a shaft collar or in some other way that prevents them from moving along the length of your shaft.

Covers protect you from rotating equipment when the clutch is mounted to the end of the shaft.

Torque arms work as an anchor for clutches in backstopping applications. Mount to the outer race of your clutch and a stationary piece of equipment.