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Formsprag CSK Backstopping Clutch for Skeet Machine

A New England manufacturer of commercial skeet shooting equipment required an overrunning clutch solution for their line of clay pigeon throwing machines. The clutch is used as a backstop to prevent oscillation of the throwing arm after each stroke. Stieber CSK backstopping clutches were selected over a competitor’s clutch due to their reliability in this high-cycle application. The CSK clutch allows free rotation in the throwing (overrunning) direction while preventing any rotation (bounce back) in the opposite direction.

CSK self-contained clutches feature a sprag type freewheel integrated into a 62 Series ball bearing. Torque transmission is ensured by a press fit assembly into a rigid outer housing with N6 tolerance, and onto a shaft with N6 tolerance.

Model CSK 25 units supplied have a 77.5 lb.ft. (105 Nm) torque capacity with a maximum overrunning speed of 5,200 RPM. The 2.05 in. (52 mm) diameter units are bearing supported, grease lubricated and protected against dust larger than .012” (.3 mm) diameter.

All CSK models are equipped with ultra-hard Formchrome® sprags which provide extra-long life, maximum wear resistance and lower maintenance costs. Formchrome sprags — exclusive with Formsprag — are made by diffusing chromium into the surface of hardened high carbon alloy steel to form a chromium-carbide alloy.

Formsprag CSK Backstopping Clutch


  • Sprag type backstopping clutch
  • 77.5 lb.ft. (105 Nm) torque capacity
  • Formchrome® sprags for long life

Contact Information

Formsprag Clutch
23601 Hoover Rd.
Warren, MI 48089 - USA
Toll Free: 1-800-348-0881 (Press #1)
Phone: 586-758-5000
Fax: 586-758-5204

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