GB558118A - Improvements in and relating to electromagnetic switches - Google Patents

Abstract

558,118. Electromagnetic switches. BRITISH THOMSON-HOUSTON CO., Ltd. June 17, 1942 No. 8313. Convention date, June 18, 1941. [Class 38 (v)] The armature 20 of an electromagnetic switch is pivoted to a leg 11 by means of a channelshaped spring member 21 fixed to the armature and having a bent-in portion 27 which rests in a groove 31 of a T-shaped projection 29 on the leg to form a knife-edge bearing. The member 21 also has spring-fingers 26 which engage the groove 30 below the projection 29 and bias the armature into the position shown in Fig. 1. When the armature is attracted downwards, its end 54, which engages a slot in a strong spring 47 pulls this spring down and after some lost motion a finger 50 on the spring 47 engages and pulls down a weaker spring 42 so that a contact 41 on it is removed from a fixed contact. Both springs 47, 42 tend to move upwards with a force that is adjustable by bolts 60, 62, and in the position shown the strong spring 47 presses on the spring 42 to ensure good contact. The invention is shown applied to a motor-controlling switch such as is described in Specification 542,189, wherein one operating coil 19 controls three magnets and releases their armatures in succession. Each armature also operates a push rod passing through the base 40 and bearing on a cross rod, so that this rod is moved and opens contacts. The last pusher rod to move also operates a lever 81 and opens contacts 80.