GB717881A - Improvements in and relating to overload protected electric switches - Google Patents

Abstract

717,881. Automatic circuit-breakers. MECHANICAL PRODUCTS, Inc. June 16, 1952 [Oct. 24, 1951], No. 15143/52. Class 38(5). An overload-released switch comprises a plunger 30 having a button 33 slidable in a block 34 and urged by a spring 42 and having at the other end forks 31 slidable in cavities 46 on either side of a block 50 secured to the bottom of the casing 10. A hollow insulating block 18 carrying the moving contacts 14 on spring arms 16 and slidably mounted on the plunger 30 has fixed thereto an inverted U-shaped bimetal latch 20 serially connected between the arms 16 and normally engaging an abutment 60 on the plunger under the action of springs 61, in which condition outwardly biased spring fingers 56 fixed to the plunger by a rivet 58, are stressed inwardly by the hollow interior of the block 18, Figs. II, III. Depressions 59 in the free ends of the fingers 56 are thus held within similar depressions 54 in the block 50 and the switch is held closed. On overload the latch 20 leaves the abutment 60 and springs 61 open the contacts, also the block 18 leaves the fingers 56 which spring outwardly, Fig. IV, and permit the spring 42 to eject the plunger, whereby the latch 20, 60 is reset and the fingers 56 are stressed inwardly within the block 18. Hence when the button 33 is depressed to close the switch, the depressions 59 snap into the depressions 54 to assist in the final movement of the contacts 14 and hold the contacts 12, 14 engaged. Specification 711,881 is referred to.