GB955589A - Electrical switch - Google Patents

Abstract

955,589. Cam-operated switches; retractive switches. WESTERN ELECTRIC CO. Inc. Oct. 25, 1962 [Nov. 7, 1961], No. 40360/62. Heading H2B. A change-over switch comprises an insulating base 25 having a slot 36 for a sliding actuator 35 and a recess 24 for wire contacts 10, 15 and 20, for example, of palladium alloy, which are located between bosses 30 and 32 and secured by filling the space between the column of bosses 30 and the column of bosses 32 with a potting compound such as an epoxy resin. The U-shaped contacts 10 and 15 are pre-flexed such that their bights 12 and 16 tend to lie in the grooves 26a, 28a and 26b, 28b while the contact 20, which is bifurcated, is spaced slightly above them. A cover 50 carrying terminals 60 is located by pins 52 and fixed by fasteners passing through holes 56 and 58 which also serve to mount the switch. A pin 38 for operating the actuator 35 extends below the actuator into a slot 40 to limit the sliding movement and cover 50 retains the actuator in the slot 36 by cooperation with surfaces 48. Cams 42 serve to lift either contact 12 or 16 into engagement with contact 20 in the limit positions of actuator 35 and a make-before-break or break-- before-make action may be provided by the relative dimensions of cams 42 and the spacing of contacts 12 and 16. A fourth contact member may be added, generally parallel to contacts 12 and 16 but above the level of cams 42, on which contact 20 rests when not lifted by contacts 12 or 16 (Figs. 7 to 10, not shown); this provides a make-before-break relationship between the fourth contact, contact 20 and either contact 12 or 16, at the same time providing break-before-make between contacts 12, 16 and 20. In an alternative embodiment (Figs. 11 to 15, not shown), the switch is mounted on a printed-circuit board by providing longitudinal grooves in the sides of the actuator which accommodate the edges of an elongated rectangular notch in the board; the wire contacts are all straight in this embodiment, and the cams 42 are replaced by an indent. The actuator may be rotary instead of sliding (Fig. 16, not shown), and in this modification comprises a disc with a projection on its periphery to act in place of cams 42. The switches are inherently bi-stable, but the actuator may be biased towards one end of its travel to provide a retractive action.