GB760466A - Improvements in electric fence units - Google Patents

Abstract

760,466 Electromagnetic interrupters. ELECTRO-MAGNETIC PRODUCTS, Ltd. Dec. 16, 1954 [Dec. 22, 1953], No. 36508/54. Class 38(5) An electric fence unit of the type in which a flywheel 17 is given periodic mechanical impulses by the armature 18 of an electromagnet is provided with spring tension means to check the movement of the flywheel and return it to its normal position, the spring 13 of the tension means forming no part of the electric circuit and being mounted on a rod 10 such that by turning the rod 10 the frequency of the oscillations of the flywheel and hence of the electric impulses to the fence may be varied. A tangential portion 13a of the spring is attached to the flywheel by means of an insulating cord 15 at a point 16 near a contact 17a on the flywheel which cooperates with a contact 18a on the armature 18 which is located in the normal position by springs 21. When the contacts 17a, 18a complete the electric circuit the electromagnet attracts the armature 18 thereby imparting a mechanical impulse to the flywheel to rotate it anticlockwise (as shown). This movement winds the cord 15 around a spindle 19 of the flywheel thereby increasing the tension in the spring 13. The flywheel is returned by virtue of the tension in the spring the effect of which becomes greater when the cord 15 leaves the spindle 19; thus the final closing of the contacts 17a, 18a is made more positive. Adjustment of the rod 10 and thus of the spring 13 is made by means of a knob affixed to the rod 10 outside the case 11. Current is led to the flywheel 17 by means of a volute spring 20.