Trip-free circuit breaker

907,595. Electrically-tripped switches. WOOD ELECTRIC CORPORATION. Aug. 17, 1959 [Nov. 18, 1958], No. 28054/59. Class 38 (5). A double-break, trip-free circuit-breaker comprises a pair of opposed insulating shells 2, 4 each having a fixed contact 8 mounted on a terminal 10 or 12 and co-operating with a movable contact 16 carried by a resilient arm 14, mounted on the shell wall together with one arm of a U-shaped bimetallic plate 46 which connects the contact pairs, Fig. 3 (not shown). For each arm 14 there is an insulating roller 20 laterally carried by the lower arm of a lever 38 pivoted at 40 between the shells, the lever being normally urged clockwise by a torsion spring 42. A manually-operable plunger 26 pivotally carries a link 22 movable between the arms of the plate 46 and carrying laterallymounted insulating rollers 18 which, on depression of the plunger, separate members 14, 20 to close the contacts 8, 16, movement of the rollers 20 being prevented by the engagement of the lever 38 with a bar 44 carried by the base of the plate 46. Fig. 1. The contacts may be opened by withdrawal of the plunger 26 or automatically on overload when upward movement of the plate 46 releases the lever 38, and the spring force of arms 14, subsequently assisted by the spring 42, returns the members to the positions shown. The contacts will be automatically opened if there is an overload, even if the plunger is held depressed, the latter having to be withdrawn to restore the members 14, 18, 20 to normal. Excessive downward movement of the bar 44 is prevented by projecting lugs 48, and the contacts in the respective shells are separated by an L-shaped insulating sheet 64.