GB1291112A - Ignition switches - Google Patents

Abstract

1291112 Mechanical switches JOSEPH LUCAS (INDUSTRIES) Ltd 6 March 1970 [17 March 1969] 13790/69 Heading H1N A vehicle ignition rotary switch which can be turned from a first "off" position to a second "on" position in which ignition and auxiliary circuits are energized and to a third "start" position wherein the starter motor is additionally energized, is retroactive from the third to the second position and cannot then be turned again to the third position until it has been moved back to the first position. The switch rotor (12, Fig. 1, not shown) has a spigot 72a which carries an annular plate 13 having a finger portion 14 moving over a cam track 21 formed in part of the switch housing 11. A spring strip 15 urges finger 14 on to a plateau portion 22 and also urges it radially outwards. When the switch is turned "on" the rotor (12) moves the plate 13 such that finger 14 rides up an incline 25; further rotation of the rotor to the "start" position causes finger 14 to be forced radially inwards to drop on to surface 23. When the switch retracts to the second position the finger 14 drops over the shoulder 24 and the rotor cannot then be moved back to the third position until it has been restored to the first position, allowing finger 14 to move radially outwards such that it will then move up the incline 25 and clear shoulder 24. Instead of a U-shaped spring strip 15 a small coiled compression spring (26, Fig. 4, not shown) may provide both the required axial and radial components of force on the plate 13.