Patent GB-184935-A (GB)
Title: Improvements in automatic electric-circuit breakers
IPC: H01H50/32
Filed: 1921-06-16
Abstract: 184,935. Railing, A. H., Angold, A. E., and Turner, H. C. June 16, 1921. Aittomatic circuit-breakers of the loose-handle type are provided with a tripping-device frictionally controlled by the handle, for the purpose of tripping the switch to give a quick break whenever the handle is moved from any ' on ' position towards the ' off ' position. One form of the invention, as applied to a toggle switch, is shown in Figs. 1 and 3. In this form, the tripping-device comprises an arm F pivoted to the handle B at B<2>, and provided with a springy extension F<2> frictionally engaging a surface B<3> on the handle. The end of the arm is formed with a slot F<1> which co-operates with a pin C on the switch member D, the width of the slot being such that the arm can rotate with the handle over a restricted range in either direction of movement of the handle. In the ' on ' position of the switch the arm is free of the tripping-mechanism, but on moving the handle towards the ' off ' position, the arm engages a lug G<1> carried by an extension of the toggle-link A and so upsets the toggle. In order that the arm may not prevent resetting of the toggle in the ' off ' position of the switch, it may be rendered inoperative in this position by providing the slot F<1> with a narrower portion which the pin C enters when the switch is open. In a modified arrangement, the pivot pin A<1> of the toggle-link A carries a cam which co-operates with a friction spring attached to the handle, so that movement of handle towards the ' off ' position carries with it the link A and upsets the toggle. The shape of the cam is such that it is out of action at the full ' on ' and ' off ' position, in order that it may not interfere with the automatic tripping of the switch or resetting of the toggle-links. The invention may be applied to catch-operated circuit-breakers as shown in Figs. 6 and 8. In this construction the switch is closed by raising links (not shown), pivoted to cranks P, P<1> connected together by a bar R. The cranks P, P' are loosely mounted on the operating-shaft N, to which is secured a crank O carrying the catch S with its tail-piece S<1>. In closing the switch the cranks P, P<1> are locked to the crank O and to the shaft N by the catch S, the switch being tripped by pressing the tail-piece S<1> towards the shaft N. An arm T mounted on the same pivot O<1> as the catch S carries a pin, one end T<1> of which loosely engages the tail-piece S', while the other end T<2> loosely engages the crank O. When the handle is moved towards the ' off ' position, the end T<2> of the pin engages a friction surface U, which causes the pin to lag behind the handle, whereupon the other end T<1> of the pin trips the catch. The friction surface U is pivoted at U<1> and controlled by a spring, and it may be provided with a lug which engages an extension O<2> of the pivot pin O<1> to retain the handle in the ' on ' position. When the switch is tripped, a lug on the crank O engages a lug U' on the friction member U and rotates this about its pivot, in order to release the handle and move the friction surface out of engagement with the pin at the full ' off ' position.