Abstract: A high performance, manually and automatically operable, trip-free magnetic circuit breaker incorporates novel means for mounting and coupling circuit breaker units to achieve multipole operation. An actuator in each pole has a shaft extending through a housing wall and fitting in splined engagement with the shaft of a corresponding actuator in an adjacent pole mounting the actuators for unison pivotal movement between a position where one of the actuators is engaged and pivoted by movement of the beaker contacts to an open circuit position in one pole for pivoting the other actuator to trip the breaker components in the adjacent pole to open the circuit in the adjacent pole. A tie-pin having a peripheral groove therein is snugly fitted into openings in the operating handles of the breaker pols and has coil springs fitted over the pin between pairs of the handles, one spring having a convolution of reduced diameter fitted into the pin groove for retaining the pin in the handle openings.

Abstract: A multi-pole circuit breaker is provided with a molded common trip bar means including a bar having integrally formed bearings defining a pivot axis remote from the bar, integrally formed links individually connected to the overload sensing means of each pole, and an integrally formed projection for releasing a latch of a trip free contact operating means.

Abstract: A multi-pole circuit breaker system includes a plurality of individual circuit breakers and at least one tripping action transfer device disposed between adjacent circuit breakers. The tripping action transfer device includes a lever pivotally supported at one end and carrying a rod shaped transfer member at its other end. The transfer member extends into the interior of the housings of adjacent circuit breakers and cooperates with their tripping mechanisms. A tripping operation of one circuit breaker engages the transfer member and causes actuation of the tripping mechanism of the adjacent breaker to initiate simultaneous tripping thereof.

Abstract: A plurality of single pole circuit breakers stacked side-by-side are interconnected by a tie rod connecting the magnetic armatures of their respective instantaneous trip means. When one pole is caused to trip because of a fault condition, a driving formation on the releasable cradle of the faulted pole delivers a hammerlike blow to a cam means on the magnetic armature. The energy imparted to the armature by this blow causes the latch carried thereby to move in the tripping direction substantially beyond the point required for releasing the cradle latch in the faulted phase. This added movement assures that the tie rod shall transmit sufficient motion to all non-faulted poles to cause tripping thereof.