Abstract: A current limiting circuit breaker including novel clutch arrangements between the contact arms of the circuit breaker and the crossbar. The clutch arrangements include cam surfaces formed on the crossbar from plastic and a cam follower attached to each contact arm. A cam surface is located on each side of each contact arm and each surface may be formed integrally with an insulating barrier. To reduce wear on the cam surfaces, each cam follower includes a roller which contacts the respective cam surface. The cam surfaces are configured to permit the contact arms to blow open under unacceptable fault conditions even though the crossbar remains stationary.

Abstract: A current limiting circuit breaker including a novel spring arrangement between the contact arms of the circuit breaker and the crossbar. The spring arrangement includes a single spring which holds the cam follower attached to each associated contact arm in contact with cam surfaces of the crossbar. The longitudinal axis of the spring is located within a plane passing through the longitudinal axis of the contact arm, wherein the plane is also perpendicular to the rotational axis of the contact arm. The cam surfaces and spring are configured to permit the contact arm to blow open under unacceptable fault conditions even though the crossbar remains stationary.

Abstract: A multi-phase circuit breaker including novel crossbar for opening and closing the circuit breaker contact arms. The crossbar is a one-piece plastic component molded to include an operating arm, insulating barriers for separating the contact arms of each phase, and the cam surfaces which interact with the cam followers of the contact arms. The operating arm is linked to the operating mechanism of the circuit breaker so that operation of the mechanism will pivot the crossbar which pivots the contact arms between their open and closed positions.