ADJUSTABLE MAGNETIC TRIP ASSEMBLY FOR CIRCUIT BREAKER

An adjustable magnetic trip unit (1) for a circuit breaker includes a torsio n spring (33) which applies a bias force to the plunger (15) of a trip solenoi d (7). The torsion spring (33) is mounted on a driven bevel gear (47) and woun d by an adjustment knob (39) coupled to a driving bevel gear (51) to adjust th e current at which the solenoid (7) is activated. An indexer (37) having peripheral flates (61) which engage a seat (55) in the circuit breaker housi ng (3) provides a pluarlity of discrete positions of the adjustment knob (39). Depressing the adjustment knob (39) against a second spring (59) unseats the indexer (37) for rotation of the adjustment knob between settings. In addition, a slide (71) with an inclined surface (85) bearing against the plunger (15) and coupled to the driven bevel gear (47), provides simultaneou s adjustment of plunger gap (67) with adjustment of the torsion spring force t o increase the range of adjustment.