GB1168567A - Improvements in or relating to Electric Switches - Google Patents

Abstract

1,168,567. Snap-action switches. HONEYWELL Ltd. 21 Dec., 1967 [29 March, 1967], No. 14205/67. Heading H1N. A three-position switch comprises a pair of conductive levers 9, 10 pivoted at 11, 12 and permanently in contact with a fixed terminal 5, the levers having contacts 14, 15 movable into and out of contact with respective fixed contacts 7, 8 on pivoting of the levers 9, 10 by means of a spring biased roller 18 carried by an operating lever 16 pivoted at 17 on the switch casing 1. The contacts 8, 15 of the lever not engaged by the roller 18 are biased open by springs, or roller 18 may engage an extension (10c) of the non-operated lever to hold said contacts open (see Figs. 4, 5). Forked arm 9b of lever 9 straddles the arm 10a of lever 10 so as to provide a mechanical bearing surface for roller 18 and a central "off" position (Fig. 2). If roller 18 is biased towards levers 9, 10 by a spring in the lever 16, should contacts 7, 14 weld, when roller 18 reaches position 18c and lever 9 does not pivot, the curved end of arm 9b causes boss 20 to abut against a stop 19, and further movement of lever 16 breaks the weld and opens contacts 7, 14. Alternatively, roller 18 may be biased towards levers 9, 10 by a spring-loaded horizontal plate in contact with the top of roller 18 and provided with a slot to accommodate the full range of movement of lever 16. Movement of collar 18 against its bias is limited by abutments above the plate.