Circuit breaker with shift guide

A circuit breaker comprising:

• a breaker case having interphase partition walls with recesses,
• a main circuit situated in the breaker case,
• an opening and closing mechanism section for the main circuit, said mechanism having a latch receiver,
• a thermal overload open-phase tripping device including bimetals corresponding to different phases of the main circuit and having operating ends;
• a differential shifter mechanism having a push shifter and a pull shifter linked to the operating ends of the bimetals of the respective phases, and an interlocking plate extending over the push and pull shifters;
• and a compensating bimetal acting as a lever for transmitting an output from the shifter mechanism to the opening and closing mechanism section to release the latch receiver, said push and pull shifters extending over the interphase partition walls in the breaker case and loosely fitted in the recesses formed at upper edges of the interphase partition walls to be slidably supported thereat,
• a case cover placed and held over the push and pull shifters of the differential shifter mechanism, and
• shifter position guides provided on an inner surface side of the case cover opposite to the push and pull shifters to restrain inclination of the shifters moving in accordance with bending displacement of the bimetals to hold the shifters horizontally.