Circuit breaker operating mechanism with high-speed low-energy tripping means

Claim 1

In an operating mechanism for a circuit breaker comprising a movable contact-actuating member, a. a toggle comprising first and second toggle links and a connecting pin pivotally interconnecting said toggle links to form a knee for the toggle, b. means for coupling said first toggle link to said movable contact-actuating member, c. a pivot pin on which said second toggle link is pivotally supported at a point spaced from said knee, d. latching means for normally holding said pivot pin in a fixed position so that hold-closed force for said circuit breaker can be transmitted through said toggle to said contact-actuating member to hold said circuit breaker closed, said latching means being releasable to release said pivot pin and thus render said toggle incapable of continuing to transmit hold-closed force to said contact-actuating member, e. said latching means comprising a piston member, a cylinder member in which said piston member is reciprocable, means for mounting said pivot pin on one of said piston or cylinder members, and a ring latch around the outer periphery of said piston member normally latching said piston member to said cylinder member, f. said ring latch comprising a split ring seated in a groove in the periphery of said piston member and a latching element normally fitting between the ends of said split ring for holding said ring in an expanded condition for blocking movement of said piston member with respect to said cylinger member, said latching element being withdrawable from its position between said ends to allow said ring to contract into a disabled position where the ring is ineffective to continue to block movement of said piston member with respect to said cylinder member.