26,530. Hermann, L. A. Dec. 6. Brakes ; driving-mechanism.-In a driving, freewheel and back-pedalling brake mechanism for bicycles, in the free position, a tooth f on a disc e within a non-rotatable cone c engages teeth on a doubly-conical nut h, so that, on commencing to drive, the nut moves to the right, thus forcing an expansible ring d' against an annular abutment k<1> in the hub shell and the n expanding the ring into contact with the shell, as shown in Fig. 1. During back-pedalling, the nut, being prevented by the tooth f from rotating, moves to the left, thus forcing the disc and the cone against the pressure of a spring p till a non-rotatable, expansible, brake ring d engages an abutment k and is expanded into contact with the hub. Projections on the cone c and nut h limit the motion of the brake and driving rings. The annular abutments may be bevelled.