Types RSBI and RBI backstop clutches consist of cylindrical inner and outer races between which are located individually spring loaded, special shape sprag elements contained in a cage. The cage is flexibly connected to the inner race to allow the sprags to engage easily during torque application. When the inner race rotates at high speed the off-centre weight of the elements causes them to rotate within the cage to produce a gap with outer race.

These clutches are designed for backstop applications on the high speed shafts of motors, gearboxes, compressors and pumps. They can also be used within slow speed barring drive. Although basically these clutches require no lubrication, their sprag design does permit the use of E.E or H.P additives.
Type RSBI is dimensionally equivalent to many competitor units; type RBI offers higher torque capacity.