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: The brake includes a housing for mounting and a disc assembly. The disc assembly engages a drive shaft for rotation therewith. A flange on the disc assembly receives a first ring and a second ring, each ring is slideably engaged to the flange for axial motion. Release plates adjacent to the second ring are free to move in an axial direction. A field cup has springs to bias the release plates against the second ring and o-rings to facilitate quiet operation of the elevator car brake. When no current flows through the coil, the release plates are biased against the second ring. Thus, the second ring engages the friction surface of the housing to park and hold the drive shaft. When current flows through the coil, the first and second release plates are drawn to the field cup, overcome the bias force of the springs and compress the o-rings.

Abstract: The brake includes a housing for mounting and a disc assembly. The disc assembly engages a drive shaft for rotation therewith. A flange on the disc assembly receives a first ring and a second ring, each ring is slideably engaged to the flange for axial motion. Release plates adjacent to the second ring are free to move in an axial direction. A field cup has springs to bias the release plates against the second ring and o-rings to facilitate quiet operation of the elevator car brake. When no current flows through the coil, the release plates are biased against the second ring. Thus, the second ring engages the friction surface of the housing to park and hold the drive shaft. When current flows through the coil, the first and second release plates are drawn to the field cup, overcome the bias force of the springs and compress the o-rings.

Abstract: A trailer is adapted to be hitched to a towing vehicle by a surge brake actuator which includes pivotally interconnected forward and rear units. When the rear unit moves forwardly relative to the forward unit, a plunger assembly is moved to a braking position to actuate a master cylinder and apply the trailer brakes. The disclosure pertains to (1) the construction and operation of the plunger assembly (2) the construction and mounting of the master cylinder (3) a friction lock for holding a breakaway cable in an emergency position when the trailer breaks away from the towing vehicle and (4) a clamping and latching mechanism for releasably coupling the forward unit of the actuator to a hitch ball on the towing vehicle.

Abstract: A trailer is adapted to be hitched to a towing vehicle by a surge brake actuator which includes pivotally interconnected forward and rear units. When the rear unit moves forwardly relative to the forward unit, a plunger assembly is moved to a braking position to actuate a master cylinder and apply the trailer brakes. The disclosure pertains to (1) the construction and operation of the plunger assembly (2) the construction and mounting of the master cylinder (3) a friction lock for holding a breakaway cable in an emergency position when the trailer breaks away from the towing vehicle and (4) a clamping and latching mechanism for releasably coupling the forward unit of the actuator to a hitch ball on the towing vehicle.

Abstract: A punch press in which pressure fluid which is introduced into a chamber is used to press a stripper against a workpiece and also to retract a piston which carries a punch. The pressure of the pressure fluid in the chamber is maintained at a substantially constant but selectively adjustable magnitude.