GB913845A - Improved electric switch - Google Patents

Abstract

913,845. Retractive switches. ARROW ELECTRIC SWITCHES Ltd. Oct. 21, 1960 [Oct. 22, 1959], No. 36132/60. Class 38 (5). A push-button switch suitable for controlling an electromagnetic contactor and which contains a pilot light to indicate that the contactor is energized has provision for testing the pilot light by manipulation of the button. The light (not shown) is housed in a translucent button 34 and depression of this button against a spring 39 causes the annular skirt 30 to depress an offset pin 24 slidable in a boss 22 carried on a plate 20 secured to the threaded mounting member 14 by screws. A basepart 10 carrying fixed contacts A, B, D and E is bolted to plate 20 and has a channel 10g in which two rectangular blocks 40 and 44, rigidly connected by a non-circular rod 42, are slidable. A spring 46 urges block 40 against the end of pin 24. A bridging contact 50 is carried on rod 42 and is normally urged against fixed contacts A and B by a spring 48. When button 34, and hence pin 24, is depressed, block 40 engages an off-centre lug 53 on bridge 50 which is thus tilted and separates from contact A before leaving contact B. Continued movement of the button 34 then causes the bridge 50 to engage and pivot on contact D such that its other end engages contact E. This bridging of contacts D and E may be used to energize a contactor. An auxiliary leafspring contact 51 is attached to bridge 50, as shown, such that the initial tilting of bridge 50 causes contact 51 to engage contact D before bridge 50 separates from contact B. Contacts B and D are in the circuit of a small transformer housed in the base 10 (Fig. 4, not shown), and this feeds the pilot light, which therefore lights upon slight depression of pin 24. In order to test the pilot light by causing contact 51 to connect contacts B and D without risking unintentional depression of the button 34 sufficient to energize the contactor, a cam surface 36 is provided on the annulus 30 such that rotation of button 34 through approximately 90 degrees causes the cam 36 to depress pin 24 just enough for contact 51 to engage contact D without contact B being disengaged. An arcuate rib 38 depends from member 30 so as to overlie boss 22 when the button is rotated and thus prevents depression of the button while in the rotated condition. Rib 38 also serves to prevent rotation of the button after depression, since its end surface then abuts the side of boss 22. Spring 39 is anchored at one end to plate 20 and at the other end to member 30, thus also providing rotary retraction of button 34.