Circuit breaker toggle mechanism with spring-biased latch plate

Claim 2

In a circuit breaker, an operating mechanism which comprises an operating mechanism settable to an ''''on'''' position in which it may constrain contacts on a movable contact carrier to be closed, the operating mechanism being collapsible by articulation of a toggle-link and a latch-frame after disengagement of a latch, in which the operating mechanism comprises a latch plate adapted to restrain the latch-frame and toggle-link against articulation only while the latch-plate is itself restrained by engagement of the latch, in which the toggle-link comprises a curved sliding face terminating in a restraining region and the latch-plate comprises a coacting formation which engages the restraining region when the latch-plate is to restrain the toggle-link against articulation and which engages the sliding face when the latch-plate is to release the toggle-link to articulate with the latch-frame, and which comprises a biassing spring which biasses the latch-plate relative to the latch-frame with a torque in opposite sense to the direction of rotation of the latch-plate, when it is engaged with the latch.

Claim 3

An operating mechanism according to claim 1, in which the sliding face is juxtaposed substantially overlapping the latch-frame when the toggle-link is in a position in which it is restrained by the latch-plate, and the toggle-link and latch-frame are in the uncollapsed position.

Claim 4

An operating mechanism according to claim 1, in which the curved sliding face of the toggle-link is shaped so as to extend from a position near the latch-frame in a direction opposite to the direction of movement of the latch-frame and toggle-link on articulating towards the collapsed position.

Claim 5

An operating mechanism according to claim 1, in which the toggle-link extends from its main portion on beyond a pivot by means of which it is articulated to the latch-frame and terminates in a restraining region adapted to restrain the latch-plate on a coacting formation of the latch-plate, the said coacting formation located at a radial distance from an axis of pivotal connection of the latch-plate to the latch frame which is less than the radial distance from an edge of the latch-plate engaged by a catch of the latch to the axis of pivotal connection of the latch-plate to the latch-frame.

Claim 6

A circuit breaker operating mechanism having a movable contact carrier for opening and closing the circuit breaker contacts and a linkage pivotally connected to the carrier and having a rigid condition for holding said contact carrier in a closed position and being biased to a collapsed condition wherein said carrier is permitted to move to an open position, said linkage comprising: a first collapsible member pivotally connected to the contact carrier, a second collapsible member pivotally connected to said first collapsible member for relative movement between rigid and collapsed positions, said second member having a curved face formed thereon and a restraining region, latch means pivotally mounted on said first member and including restraining means, said restraining means being engageable by said restraining region to prevent movement of said second member out of its rigid position when said latch means is in a first position, said restraining means moving out of engagement with said restraining region when said latch means is moved from said first position to a second position to permit said second member to move to its collapsed position, catch means movably mounted on said first member for engaging said latch means to maintain it in said first position when said catch means is in one position, said catch means being movable to a second position to disengage said latch means whereby said latch means may be moved to said second position, the engagement between said second member and said latch means acting to urge said latch means into frictional engagement with said catch means, spring means engaging said latch means for biasing the same away from said catch means to minimize said frictional engagement to reduce the tripping force necessary to move said catch means to its second position, said restraining means engaging said curved surface when said latch member is released from said catch means to limit movement of said catch means under the influence of said spring means.

Claim 7

A circuit breaker operating mechanism having a movable contact carrier for opening and closing the circuit breaker contacts and a linkage pivotally connected to the carrier and having a rigid condition for holding said contact carrier in a closed position and being biased to a collapsed condition wherein said carrier is permitted to move to an open position, said linkage comprising: a first collapsible member pivotally connected to the contact carrier, a second collapsible member pivotally connected to said first collapsible member for relative movement between rigid and collapsed positions, said second member having a curved face formed thereon and a restraining region, latch means pivotally mounted on said first member and including restraining means, said restraining means being engageable by said restraining region to prevent movement of said second member out of its rigid position when said latch means is in a first position, said restraining means moving out of engagement with said restraining region when said latch means is moved from said first position to a second position to permit said second member to move to its collapsed position, catch means movably mounted on said first member for engaging said latch means to maintain it in said first position when said catch means is in one position, said catch means being movable to a second position to disengage said latch means whereby said latch means may be moved to said second position, the engagement between said second member and said latch means acting to urge said latch means into frictional engagement with said catch means, spring means engaging said latch means for biasing the same away from said catch means to minimize said frictional engagement to reduce the tripping force necessary to move said catch means to its second position, said restraining means engaging said curved surface when said latch member is released from said catch means to limit movement of said catch means under the influence of said spring means.