GB583331A - Improvements in electric snap-action switches - Google Patents

Abstract

583,331. Electric motor controllers and switches. GRAY, W. T., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. Oct. 18, 1944, No. 20170. [Classes 38 (iii) and 38 (v)] In a snap-actioh switch, specially for use in traction controllers, movement of an operating member such as a cam 16 causes an electromagnet 15 to be energised to hold a contact arm 3 fast while a spring 11 is being strained; further movement de-energises or reverses the energisation of the electro-magnet allowing the arm 3 to move into its other position. In the form shown, the arm 3 is pivoted at 4 and carries an armature 5 which moves between the poles 6, 7 of the electro-magnet under the action of a spring-loaded pin 10 on a cam-actuated operating-arm 9 carrying an arcuate contact 13 co-operating with a contact 14 to 'energise the magnet 8. In the closing movement, the pin 10 presses on the contact arm and simultaneously contacts 13, 14, energise the magnet and hold the armature 5 against the arm 6. When the contact 13 moves past the fixed contact, the magnet is de-energised, thus allowing the contact arm to move by the action' of the pin 10. The opening movement of the cam 16 first remakes contacts 13, 14, thus energising the magnet and holding the armature against the arm 7, and then breaks this circuit to allow motion of the contact arm under the action of a " throw-off " spring 18. In a modified form the spring-loaded pin 10 may be mounted on the contact arm 3 and directly operated by the cam whilst an auxiliary switch may be used to control the electro-magnet. A modified form of electromagnet may be used, Figs. 2 and 3 (not shown).