Abstract: A fastenerless electromagnetic trip assembly employs minimal parts for effecting the release of a set of circuit breaker contacts. The parts include an armature, an armature bias spring, a yoke and a trip bar, all of which may be retractably supported in associated compartments within the circuit breaker housing. The yoke provides an electromagnetic field in response to electric current flowing in the circuit breaker. A spring biases the armature until the electromagnetic field reaches a predetermined strength, at which point the bias is overcome, and the armature strikes the trip bar and is drawn toward the yoke, thereby causing the trip member to actuate the release of the circuit breaker contacts.

Abstract: A circuit breaker for breaking current conduction between line and load connectors in response to tripping of a bimetallic thermal element as a result of an over-current condition is disclosed. According to the invention, a trip crossbar is permitted to translate as well as rotate to relieve stress on the thermal element.