| 摘要 |
487,342. Snap - action switches. BRITISH MECHANICAL PRODUCTIONS, Ltd., COOK, C. R., and DEAKIN, S. T. Dec. 18, 1936, No. 34902. [Class 38 (v)] A switch, wherein successive operations in one direction of an operating member which moves in a substantially rectilinear manner cause the contact element alternately to open and close the switch by engaging one of two abutments and moving them in opposite directions to present them for alternate engagement by the operating member is arranged for mounting in the skirting board, has mechanism carried by a metal chassis 1, 2, 3 and enclosed in a case 35, 36 and is operated by downward pressure of the foot on a plunger 9 against a return spring 10. Fixed contacts 11 mounted upon an insulating plate 12 carried by a tongue 13 of the chassis are engaged by moving contacts 4 carried by a U-shaped member 19 as shown in Fig. a diagram of the link and toggle mechanism only. In the open position of the switch a flange 25 of the plunger 9 engages a hook 24 on the right-hand member 6 of a system of four pinjointed links 5, 6, 7 and 8, the lowest member 8 of which is pivotally mounted at 21 to the chassis and has pivoted to it a rod 18 which carries a compression spring 27 and is slidable through the base of the member 19. The three members 18, 19 and 27 form a dead centre snap-action mechanism so that when plunger 9 is depressed the link 6 moves down substantially parallel to link 5 which moves up, and the pin 20, moves past the pivot 17 carrying the member 19, which moves over to carry contacts 4 into engagement with contacts 11 with a snap action, positive initiation of this movement being given by arms 28 extending from the pivot 21 acting on shoulders 29. The force exerted by spring 27 in conjunction with the effect of the co-operation between link 6 and a lug 40 on link 8 then causes engagement of hook 23 on link 5 with the flange 25 when the plunger is released, the curvature of the link edge 26 against which the flange 25 slides, minimizing the shook of this action. Opening of the switch with a snap action is now effected in a similar manner by the next depression of the plunger 9, and a position indicator 38 is operated by the lateral movements of links 5 and 6. The switch also has a three pin socket with an interlocking shutter as described in Specification 487,063, [Group XXXVI].
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