GB274194A - Improvements in or relating to control means for multiple-way electric circuit devices - Google Patents

Abstract

274,194. Ollerenshaw, R. E. April 15, 1926. Thermal switches; switches, quick-action.-A switching-device for controlling an illuminated sign comprises a thermal element, e.g. a bimetallic strip 23, carrying a switch arm 31 adapted to engage in succession a series of contacts 32 - - 35 connected to lamps 2 - - 5. The device is combined with a quick-action interrupter 15, 8, in such a manner that after the lamps have been lit one after the other they are all extinguished simultaneously. With the parts in the position shown in Fig. 3, current flows through lamp 1 heating winding 25, and contacts 15, 8. The strip 23 becomes hot and bends downwards stressing a spring blade 28 on a lever 12, which is prevented from moving by the engagement of the member 8 with a spring-mounted wedge 10, and causing the arm 31 to engage successively the adjustable contacts 32 - - 35. Eventually the member 8 slips over the wedge 10 and the parts move rapidly into the position shown in Fig. 4 in which the circuit to all the lamps is broken at the contacts 15, 8. The strip 23 then cools and returns the parts into their original position. An arrangement is provided for shunting a portion of the heating winding 25. In a modification, the forked member 12 acts on a bowed spring which takes the place of the wedge 10 in providing a quick action. The member 23 may also be flexible instead of the member 28.