Operating mechanism of a low voltage electric circuit breaker

A multi-pole circuit breaker having an insulating housing, a plurality of poles positioned in said housing, an operating mechanism supported in said housing, a plurality of movable contacts operated by said operating mechanism, said operating mechanism comprising:

• a toggle joint with a lower link and an upper link connected by a knee pivot pin;
• a trip hook pivotally mounted on a fixed pivot, said upper link being operatively connected to said trip hook;
• a handle supporting rocker pivotable between closed and open positions to open and close said contacts;
• a bar of insulating material, connected mechanically to the lower link of the toggle joint, to drive the movable contacts of the poles between closed and open positions;
• a spring having a first end anchored to the rocker and a second end anchored to said knee pivot pin of the toggle joint;
• a releasable latch to engage the trip hook in a latched position, said upper link having an extension forming a drive lever with a drive lug cooperating with said rocker, said drive lug rotating to move said trip hook to said latched position when said rocker is moved by the handle towards the open position, said rocker being operable between open and closed positions to operate said spring, when said latch and trip hook are in said latched position, to alternately collapse and allow expansion of said toggle joint to respectively open and close said contacts;
• and
• a trip device automatically operable upon the occurrence of overload current conditions above a predetermined value to effect release of said latch whereupon said spring operates to move said movable contacts to the open position.