GB486640A - Improvements in three position electric switches - Google Patents

Abstract

486,640. Snap - action switches. ARROW - HART & HEGEMAN ELECTRIC CO. Sept. 28, 1937, No. 26246. Convention date, Oct. 21, 1936. [Class 38 (v)] A three-position tumbler switch comprises a dolly 40 which, by means of teeth, drives a cam plate 52 pivoted on a spindle 54 on which is also pivoted a switching member 62 formed of two plates joined by a bracket 68. Transmission springs 58 are connected between a strut 56 on cam plate 52 and lugs 60 on member 62. A pin 32 passes through slots 76 in member 62 and is pressed upwards by a spring 78. The pin 32 also passes through latching slots 80 in fixed frame plates 33, 34 and the ends engage in slots in insulating plates 28, 30 carrying contact members 24, 26 adapted to be slid from a central off position into and out of engagement with pairs of contacts 18, 22, and 12, 20 of which there are two pairs at each end of the base. The slots 80 are shaped as shown in Fig. 6 in which the parts are shown in one of the on positions, the pin 32 being spring- pressed into engagement with a recess 80b. If now the dolly is moved so as to move the cam plate 52 clockwise, the springs 58 are strained until the cam plate moves pin 82 out of recess 80b allowing member 62 to move rapidly to the central off position. The pin 32 comes to rest against a projection 80d as shown at X, Fig. (i, and is prevented from rising by the cam plate 52, further movement of the dolly merely resulting in straining springs 58. If, however, the dolly is released so as to move to its central position, a recess 52d in the cam plate allows the pin 32 to rise into a recess 80c and the switch can then be moved by the dolly into the other on position. In a modification, the projection 80d is carried on a separate plate having a slight pivotal movement so that the position in which member 62 is arrested is truly central for both directions of movement. In this case the central position is also a contact-making position.