Abstract: This invention provides a roller screw drive mechanism (60) driven by an electric torque motor (50) through a gear drive (58,58',58") associated with either the screw (64,94) or nut (62,92) member of the roller screw drive mechanism. Rotation of the gear drive (58, 58', 58") by the torque motor (50) effectively moves the other member of the roller screw drive mechanism into axial engagement with the brake pressure plate (32) for braking action in response to an electrical control signal fed to the torque motor. A plurality of torque motor driven roller screw drive mechanisms are mounted in a balanced arrangement about the axis of the wheel and brake assembly to effectively apply and release a brake pressure force on the brake pressure plate in response to an electrical control signal to the torque motors.