GB942324A - Electric switches - Google Patents

Abstract

942,324. Retractive switches. JOSEPH LUCAS (INDUSTRIES) Ltd. Aug. 10, 1961 [Aug. 15, 1960], No. 28126/60. Heading H2B. A switch in which the operating member is arranged for rotary and axial movement has a spring-loaded contact arm pivotally mounted on a carrier which rotates with the operating member and cam means movable axially with the spindle to move the arm against the spring- pressure. As described in relation to a starter switch for a compression ignition engine, rotation of a knob 33 rotates a carrier 38 carrying two pairs of contacts 41, the contacts of a pair being connected to form a single bridging contact. Contacts such as 25 are arranged in a circle on the base 21 and in a first, or OFF, position the bridging contacts 41 complete no operative circuit. Rotation of the knob 33 and contacts 41 to the next or NORMAL position causes circuits to be completed to auxiliary apparatus, e.g. a radio. Further rotation, against a spring 51, to the third or START position completes also the circuit to the starter motor. Inadvertent movement of the switch between OFF and NORMAL positions is said to be prevented by means of projections 40 on the carrier 38 and corresponding projections 39 on a disc 36 fixed against rotation. In the central NORMAL position only, a projection 50 on the shaft 32 allows the knob 33 to be depressed, thus moving axially a cam surface 49 which engages a contact arm 43 pivotally mounted on the upper surface of the carrier 38. Bridging contacts 44 carried by the arm 43 are thus moved outward to complete the circuit to a starter aid such as an inlet manifold heater. Upon rotation of the knob 32 to the START position, the heater circuit is maintained and the starter motor circuit completed. When the knob 32 is released, spring 51 returns it to the central position and spring 34 then retracts it so that the switch regains its NORMAL position.