Protective switching apparatus

An electric circuit breaker having a switch mechanism comprising:

• i. a stationary contact and a movable contact adapted to cooperate together to make the circuit through the breaker in a closed position of said contacts and break the circuit in an open positon of said contacts;
• ii. an elongate movable contact holder arm having first and second ends and first and second bearing surface portions, the first end than the second surface portion, the movable contact being carried at the first end, the movable contact arm having an ON position in which the contacts are closed and first and second OFF positions in which the contacts are open;
• iii. overload current responsive tripping means including a lock forming a retracting fulcrum taking an unretracted position when the tripping means is untripped and a retracted position when the tripping means is tripped due to an overload;
• iv. a toggle joint mechanism including:
• a manually operable actuating member pivotably mounted about a fixed point and having ON and OFF positions;
• a link connected to the actuating member at a first end of said link, said link having a second free end;
• v. a torsion spring mounted on a fixed axis and having a first leg on which said free end bears when the movable contact holder arm is in its ON position, the first leg then acting against said link, and from which said free end is disengaged when the actuating member is in its OFF position while the movable contact holder arm is in either one of its first and second OFF positions, said torsion spring further having a second leg which bears on the second bearing surface portion of the movable contact holder arm in the ON position of said movable contact holder arm while first and second legs have free ends which are mutually abutting to disengage the second leg from the movable contact holder arm in either one of the first and second OFF positions of said movable contact holder arm;
• vi. the free end of the link being in such cooperating engagement with the first bearing surface portion of the movable contact holder arm that said movable contact arm will be pivoted about said free end through action of the first leg of the spring from its ON to its second OFF position when the retracing fulcrum passes from its unretracted to its retracted position, and
• vii. the movable contact holder arm being pivoted about the retracting fulcrum when said retracing fulcrum is inits unretracted position and the actuating member is pivoted to its OFF position.