EMF actuator

The electromechanical parking brake is the same as a handbrake. The EMF actuator is integrated into the brake caliper at the rear axle and acts directly on the brake piston. The parking brake is operated using the parking brake button in the center console.

The parking brake serves to secure the stationary vehicle to prevent it rolling away. The Automatic Hold brake retaining force is applied electromechanically to the rear wheels via both EMF actuators. The Dynamic Stability Control controls both EMF actuators.

The power is transferred to a two-stage planetary gear train via the servomotor and a belt drive. A spindle with nut in the brake piston ensures the self-locking facility. The power is transferred to the brake piston via the spindle and nut. The brake piston exerts force on the brake pads in the same way as hydraulic operation, and the pads are pressed onto the brake disc. The self-locking facility of the spindle maintains the retaining force. The vehicle is also securely held in position when in a de-energized state.

Courtesy of BMW OF NORTH AMERICA, INC.