Abstract: A rotational coupling device includes an armature configured for coupling to a shaft for rotation with the shaft about an axis, but axially movable relative to the shaft. An electromagnet assembly is disposed on one side of the armature and fixed against rotation. A collar is disposed on the opposite side of the armature. The collar is configured for rotation with the shaft, but fixed against axial movement relative to the shaft and includes a permanent magnet. When a current having a first polarity is provided to the electromagnet assembly, the armature moves in one axial direction into engagement with a member of the coupling device to transmit a torque between the member and the armature. The permanent magnet urges the armature in the opposite axial direction to disengage the armature from the member when the current is not provided to the electromagnet assembly.

Abstract: A rotational coupling device includes an armature configured for coupling to a shaft for rotation with the shaft about an axis, but axially movable relative to the shaft. An electromagnet assembly is disposed on one side of the armature and fixed against rotation. A collar is disposed on the opposite side of the armature. The collar is configured for rotation with the shaft, but fixed against axial movement relative to the shaft and includes a permanent magnet. When a current having a first polarity is provided to the electromagnet assembly, the armature moves in one axial direction into engagement with a member of the coupling device to transmit a torque between the member and the armature. The permanent magnet urges the armature in the opposite axial direction to disengage the armature from the member when the current is not provided to the electromagnet assembly.

Abstract: An electromagnetic brake is provided in which short duration current pulses move the brake between engaged and disengaged states. A first current pulse having a first polarity is delivered to a conductor within a field shell when the brake is engaged and establishes an electromagnetic circuit including the field shell and an armature plate that urges the armature plate away from a rotating friction plate and towards the field shell to disengage the brake. A magnetic circuit is maintained after termination of the first current pulse due to a remanence in at least one of the armature plate and the field shell. A second current pulse having a second polarity opposite the first polarity delivered to the conductor when the brake is disengaged weakens the magnetic circuit thereby allowing a spring to move the armature plate away from the field shell and towards the friction plate to engage the brake.

Abstract: An electromagnetic brake is provided in which short duration current pulses move the brake between engaged and disengaged states. A first current pulse having a first polarity is delivered to a conductor within a field shell when the brake is engaged and establishes an electromagnetic circuit including the field shell and an armature plate that urges the armature plate away from a rotating friction plate and towards the field shell to disengage the brake. A magnetic circuit is maintained after termination of the first current pulse due to a remanence in at least one of the armature plate and the field shell. A second current pulse having a second polarity opposite the first polarity delivered to the conductor when the brake is disengaged weakens the magnetic circuit thereby allowing a spring to move the armature plate away from the field shell and towards the friction plate to engage the brake.

Abstract: A brake is provided that employs an electromagnetic or magnetic circuit to disengage the brake and in which a reed switch is used to indicate an operating condition of the brake. The reed switch is positioned across an air gap between two members of the electromagnetic or magnetic circuit. The state of the reed switch changes in response to flux leakage at the air gap and may be used to monitor for potential failures in the operation of the brake including a failure to operate due a lack of current or the failure of the brake to disengage due to an obstruction.

Abstract: A brake is provided that employs an electromagnetic or magnetic circuit to disengage the brake and in which a reed switch is used to indicate an operating condition of the brake. The reed switch is positioned across an air gap between two members of the electromagnetic or magnetic circuit. The reed switch is oriented such that a longitudinal axis of the reed switch extends in a direction other than parallel to one or both of (i) the axis of rotation for rotating components of the brake and (ii) a direction of a magnetic force at a point in the air gap where the magnetic force is greatest.

Abstract: A brake is provided that employs an electromagnetic or magnetic circuit to disengage the brake and in which a reed switch is used to indicate an operating condition of the brake. The reed switch is positioned across an air gap between two members of the electromagnetic or magnetic circuit. The reed switch is oriented such that a longitudinal axis of the reed switch extends in a direction other than parallel to one or both of (i) the axis of rotation for rotating components of the brake and (ii) a direction of a magnetic force at a point in the air gap where the magnetic force is greatest.