GB884774A - Improvements relating to electrical switches - Google Patents

Abstract

884,774. Cam-operated switches. NETTLE ACCESSORIES Ltd. Feb. 9, 1960 [Feb. 10, 1959], No. 4569/59. Class 38 (5). A switch adapted to be actuated by a pull cord has a rotor with an even number of teeth, so arranged that alternate teeth close the switch, the rotor together with its pivots being moulded in one piece in insulating material. A pawl 14 pivotally mounted in a stirrup 15 is urged by a spring 17 and plate 16 into contact with a rotor 13 pivoted in slots 12 in each half of the casing 1, 2. Each pull on a cord 18 turns the rotor by one tooth, the pawl riding over the teeth on the return stroke, and alternate teeth are wide enough to move two spring-loaded contact blades 9 away from their corresponding contacts 7, 8 and 5, 6. The intervening teeth are narrower and pass freely between the contact blades. The rotor is located in the ON and OFF position by a spring blade 20 which presses on two adjacent teeth. The upper end of a two-pronged lever 22 rests in the ON position on a wide tooth and its lower portion is biased to the right (in Fig. 2) by the lower portion of the spring blade 20. When the switch is open, the spring 20 turns the lever 22 about its fulcrum 23, the prongs resting beside a narrow tooth, to move the shutter 25 aside and uncover the legend " OFF." In an alternative embodiment, the switch acts as a change-over switch, terminals 3 and 5 being strapped together. The rotor 13 then has alternate teeth off-set axially so that successive strokes of the pawl 14 connect either terminal 4 or 6 alternately to the common conductor, the indicator being omitted in this application. Both the rotor 13 and pawl 14 are made of a low-resistance plastic material such as nylon.