Type RSBW is a DC sprag type freewheel. It is self-contained, centered by plain bearings for low rotational speeds and sealed using shield protected O Rings.

Unit is delivered grease lubricated ready for installation in either a horizontal or vertical position. Primarily used as a backstop, this type provides a high torque capacity with a minimum space requirement. The design allows installation in difficult environments such as high humidity or water splash areas. A bolt, secured to a fixed part of the machine and passing through the slot in the torque arm, provides the rotational stop. Radial clearance on this bolt should be equal to 1–3 % of the slot width. The torque arm and the bearings must not be prestressed.