GB637837A - Improvements relating to electric lever operated switches for alternating current circuits - Google Patents

Abstract

637,837. Tumbler switches. PARSONS, Ltd., C. H., and HANDLEY, G. B. Dec. 9, 1947, No. 32405. [Class 38 (v)] A switch for A.C. circuits comprises a contactbar 34 having secured to its underside by a rivet 40 a blade-spring 39, the ends 41 of which are located in recesses 42 formed by the switch-body 20 and cover 21. The rivet 40 also secures the bar 34 to an insulating yoke 28 slidable on a rod 23 having a head 33 between which and a collar 30, also slidable on the rod and abutting a shoulder 46 thereon, is located a compressionspring 32. Further weaker compression springs 27, 29 are positioned on the rod between respectively, the yoke 28 and the cover 21 and the collar 30, the spring 29 being weaker than spring 27. The collar 30 slides in a bore 30a in the body 20 to guide the rod 23 when operated by a dolly 22 pivoted to it at 24 and having faces 25a, 25b co - operating with the surface of the cover 21. As the dolly commences to move from the " off " position, the rod 23 rises, the springs 27, 29 are somewhat compressed and the blade-spring 39 engages the top of the recesses 42, Fig. 7. Further movement brings the collar 30 against the yoke 28 and further compresses the spring 29. Continued movement compresses the springs 27, 32 and flexes the blade-spring 39, and the bar 34 bridges the fixed contacts 35. The switch is maintained in the " on " position by the dolly face 25b bearing on the cover. On reverse movement of the dolly, the blade-spring 39 unbends and gives an initial small separation to the contacts 34, 35, after which the springs 27, 29, 32 expand and the contact bar 34 moves to the fully open position. Rotation of the rod 23 is prevented by a pin 47 passing through it and engaging grooves 49 in a bore in the cover. In an alternative construction, Fig. 11, the rod 23 has a cranked pin 44 against which press the spring 27 and yoke 28. The cranked end of the pin extends through a plate 45 on the rod and cooperates with a recess 49a in the cover, thereby preventing the rod rotating. In another modification (Fig. 10, not shown), an insulating block is interposed between the contact bar 34 and the blade spring 39 and may serve as the yoke 28. The switch illustrated is a doublepole switch having a pair of bars 34.