Contact control arrangement for high amperage molded case circuit breaker

Abstract

A pair of toggle links in a high amperage molded case circuit breaker are driven over center in response to the discharge of a closing spring for pivoting a plurality of blades and closing the breaker contacts. A latch link pivotally connected to the upper toggle link also is engaged by a pivotable latch along an arcuate surface on the latch so that shock forces are transmitted along a radial line of the latch for minimizing inadvertent rotational forces on the latch. The latch release force is rendered dependent on the spring force exerted through the links from the blade overtravel springs and the coefficient of friction of the latch arcuate surface. The force exerted through the links is controlled by an adjustable stop having an inclined surface engaging the pivot connection between the toggle links. Large movements of the stop provide small changes in the inclined surface position relative the pivot connection to provide small changes in the overcenter position. An adjustment assembly controls the distance the latch pivots for disengaging the latch link and a spring associated with the adjustment assembly provides additional shock isolation. Helical coil springs of cadmium copper alloy between the blades and a journal serve to eliminate pigtail connections for the blades.