Series 20 and 50 clutches provide all the outstanding features of the Formsprag design for backstop applications with the exception that the customer supplies his own inner race, and provides the concentricity between the races.

This assembly is particularly advantageous on such applications as gear reducers where the backstop can be incorporated into a bearing bore and an extension of an existing shaft can be used for an inner race.

The outer surface of this clutch is basically the same as the outer surface of a standard bearing. The tolerance on the outer diameter is held to insure a proper fit (without pressing) into a continuation of the bore which accommodates the adjacent bearing. The tolerance on this bore should follow the bearing manufacturer’s recommendation for the bearing used . Taper within this bore should not exceed .0002 inch per inch.