GB896121A - Improvements in snap acting electric switch - Google Patents

Abstract

896,121. Retractive switches; snap-action switches; switch contacts. ROBERTSHAWFULTON CONTROLS CO. Sept. 30, 1958 [Jan. 13, 1958], No.31195/58. Class 38 (5). A switch comprises actuating and actuated members, each of which has a free end, the members being interconnected by a resilient over-centre snap-action means and being operably connected at their non-free ends to cause a wiping movement of the movable contact, which is on the actuated member, in a direction perpendicular to the snap-action movement. In one form, Fig. 1, the actuated member comprises an arm 22 mounted at 24 and carrying a contact 20 movable between fixed contacts 16, 18. The actuating member 36 is attached at 48 to a cranked part of the arm 22 and at its free end has notches 44 in which is pivoted a lever 50 connected by a tension spring 66 to the arm 22. Stops 63, 64 on the lever 50 limit mdvement thereof and, when force is applied to the member 36, increases the contact pressure until the contact is. snapped over. As the member 36 is tilted, the arm 22 bends about a projection 34 and thus produces the wiping action. In a modification, Fig. 7, the lever 150 engages pivots on the arm 122 and is connected by a spring 166 to the actuating member 136. In another form, Fig. 8, the member 236 has a pivot 235 and bears on a bell-crank lever 270 in turn pressing on the cranked portion 226 of the arm 222. The coil-spring and lever may be replaced by a C-spring 366 arranged between the free ends of the member 336 and arm 322, Fig. 9. In the above arrangements, the switch restores when the actuating member is released, due to the resilience of the cranked portion. In further arrangements, Figs. 13 to 18 (not shown), a separate coil return-spring is provided, and in Figs. 13, 14 (not shown), the actuated member is embraced by the actuating member, whereas in the other embodiments these two members are superimposed.