Bistable Brake

A brake, comprising:

• a friction plate configured for coupling to a shaft for rotation with the shaft about an axis of rotation;
• a pressure plate disposed about the axis on a first side of the friction plate and fixed against rotation;
• an armature plate disposed about the axis on a second side of the friction plate;
• a field shell disposed about the axis on an opposite side of the armature plate relative to the friction plate;
• a spring biasing the armature plate in a first axial direction towards the friction plate and away from the field shell to engage the brake;
• and,
• a conductor disposed within the field shell
• a controller configured to
• deliver a first current pulse to the conductor when disengaging the brake, the first current pulse having a first polarity and configured to establish an electromagnetic circuit including the armature plate and the field shell that urges the armature plate in a second axial direction away from the friction plate and towards the field shell, a magnetic circuit including the armature plate and the field shell maintained after termination of the first current pulse due to a remanence in at least one of the armature plate and the field shell, the magnetic circuit generating an attractive force greater than a biasing force of the spring;
• and,
• deliver a second current pulse to the conductor when engaging the brake, the second current pulse having a second polarity opposite the first polarity and configured to weaken the magnetic circuit thereby allowing the spring to move the armature plate in the first axial direction away from the field shell and towards the friction plate.

A brake, comprising:

• a friction plate configured for coupling to a shaft for rotation with the shaft about an axis of rotation;
• a pressure plate disposed about the axis on a first side of the friction plate and fixed against rotation;
• an armature plate disposed about the axis on a second side of the friction plate;
• a field shell disposed about the axis on an opposite side of the armature plate relative to the friction plate;
• a spring biasing the armature plate in a first axial direction towards the friction plate and away from the field shell to engage the brake;
• and,
• a conductor disposed within the field shell
• wherein at least one of the armature plate and the field shell has a remanence that generates, after the brake is disengaged by providing a current pulse to the conductor and following termination of the current pulse, an attractive force between the armature plate and the field shell greater than a biasing force of the spring.