Patent ID: 7458442

Claim:
In an electromagnetic braking system comprising a brake stack, a ram shiftable in a first linear direction toward and against the brake stack and a second liner direction opposite the first linear direction, and a motor having an output shaft mechanically connected to the ram and rotatable in a first rotation direction for moving the ram in the first linear direction and in a second rotation direction for moving the ram in the second linear direction, a method for performing a park brake operation with the electromagnetic braking system and limiting the force exerted by a cooling brake stack on the motor comprising the steps of: providing at least one friction member having a friction surface adjacent to the motor output shaft; moving the at least one friction surface against the motor output shaft in a non-locking manner; and holding the at least one friction surface against the output shaft with a predetermined force to perform the park brake operation; whereby the predetermined force is low enough to allow the motor output shaft to slip relative to the friction surface when a force on the output shaft exceeds a predetermined level, so that said motor is back driven, a torque on said output shaft is consequently reduced until slipping of said output shaft stops, and said output shaft is again held in position to continue to perform said park brake operation.