GB631167A - Improvements in and relating to electromagnetic switches - Google Patents

Abstract

631,167. Electromagnetic switches. BRITISH THOMSON-HOUSTON CO. Ltd. May 1, 1945, No. 11005. Convention date, May 2, 1944. [Class 38(v)] An electromagnetic switch comprises an electromagnet 12 having an armature 16 pivoted at two points at its lower end and to which is attached a spring 30 carrying a movable contact 31 which engages a fixed contact in an arc chute 11. Fig. 3 shows the method of pivoting the armature to a bracket 15 secured to an extension 14 of the magnet core. A rubber or other resilient member 17 is passed through an opening in the armature. The member 17 is provided with fl a n g e s 24 which grip the armature o n both sides, and with -a central hole e through which a bolt 19 is passed which secures the member 17 to the bracket 15. The member 17 normally biasses the armature away from the coil 12 but allows movement of the armature when the electromagnet is excited. Two brackets 15 are provided with two similar rubber pivots for the armature as shown at 17, 18 in Fig. 1. The armature is additionally biassed by a spring 26, Fig. 2, which bears against an arm 28 secured to the lower end of the armature which may be provided with a core piece 29 co-operating with the core 29a of the magnet. The spring 30 presses at its upper end against a bracket 32 secured to the armature and the pressure of the spring on the armature can be varied by inserting washers between the bracket 32 and the armature and also by means of an adjusting screw 35 extending through the spring at its lower end which is bent as shown at 31a to rest against the armature. A flexible conductor 61 connects the contact 31 with a terminal member 62. A fixed bolt with an adjustable nut 41 limits the movement of the armature away from the magnet. The upper end of the armature is provided with two projections 38, 39 which actuate two press-button interlock switches 40 situated one on each side of the chute 11. Fig. 5 shows one of the switches with the two casing parts 42, 43 separated. Each part carries a fixed contact 46, 47 in electrical connection with a fixing bolt 59, 60. Moving contacts are carried by a conducting bridging member 51 which is moved by the plunger 50. In the form shown in Fig. 5 the fixed and moving contacts are normally closed by springs 54, 55. By removing the member 51 and replacing it in the reversed position the switch is converted to one with normally open contacts.