Abstract: A compactly sized spring-applied electromagnetically released radial face friction brake, with a ball-pocket torque booster producing increased torque capacity is disclosed. The friction brake is released by energization of an electromagnetic coil attracting an axially movable armature, which nullifies the spring operator force to release the brake. The friction brake includes a driving hub having a plurality of bosses which engage a plurality of slots in a rotatable member to be braked. Thus, the driving force from the hub is distributed to the rotatable member so that both brittle and nonbrittle friction materials can be used to form the rotatable member. In addition, a collar is provided to limit the axial movement between the armature and the stationary ferromagnetic housing which contains the electromagnetic coil therein. Thus, as the friction surface on the rotatable member wears away, the magnetic air gap cannot become so great as to prevent brake disengagement.