GB600224A - Improvements in or relating to alternating current electric switches - Google Patents

Abstract

600,224. Snap-action switches. SIMPLEX ELECTRIC CO.. Ltd., and HUNT, J. J. H. Sept. 18, 1945, No. 24045. [Class 38 (v)] In a switch for A.C. circuits and comprising two pairs of contacts in series, one pair is opened first to provide a micro-gap which can be pre-set by an adjustable abutment 53,. 86. The knob of a rotary switch, Fig. 2, has a portion 23 engaging a square shank 19 of a spindle, which is biassed to one of four positions by springs on a post 26 engaging a further squared shank near its base, and the portion 23. On rotation of the spindle 19 from the " on " position, a cam 27 thereon presses apart friction-reducing spring strips 35 and sliding pins 37. Pins 37 cause floating bars 38 first to open contacts 39, 49 against weak springs 45 and then contacts 40, 50 against stronger springs 47, as projections 46 strike pre-set abutment screws 53. Pins 41 engage holes in the switch body 15 to limit endwise movement of the bars 38. In Fig. 4, a lever 59 is pivoted at 58 between plates 56 and carries rollers 62 on either side, engaging cams 68 on levers 66 pivoted at 67. Each lever 66 is provided with a nose 71 engaging a bar 72 mounted on a resilient strip 81 and carrying contacts 73, 74 bridging contacts 75, 78. The nose 71 is nearer to spring 85 so that contacts 73, 75 open first to a distance pre-set by a screw 86, which may either pass through the spring 85, as shown, or be located to one side of it, Fig. 7 (not shown).