GB740780A - Improvements in electro-magnetically actuated indicators - Google Patents

Abstract

740,780. Electric indicators. DOWTY EQUIPMENT, Ltd., and SNELL, M. S. June 29, 1954 [June 29, 1953]. No. 17985/53. Class 40(1) An electric twoposition indicator comprising a moulded spherical eyeball with a moulded-in iron armature which is attracted by an electro - magnet against a spring is characterized in that the armature is eccentrically mounted so that the magnetic attraction force increases as the eyeball is rotated from one position to the other. As shown (Figs. 1. 2), the eyeball 31 consists of an inner moulding 37 comprising two laterally displaced hemispheres supporting an iron armature 39, and a similarly shaped brass counter weight 41, the whole being surrounded by a further moulding 45 to present a completely spherical external surface. The completed eyeball is mounted on a shaft 32 under a window 23 and above an electromagnet consisting of a coil 12 with central core 13. Thus energization of the coil 12 attracts the armature 39 against a spring 47 with a force which increases as the eyeball rotates because of the eccentricity of the armature 39 relative to the shaft 32, and which is enhanced by making the width of the armature increase to that part which is nearest the surface of the ball. Movement of the eyeball is restricted by a stop-pin 43 projecting from the eyeball 31 to butt against a dished washer 25 in the extreme positions. The alternatively exposed portions of the eyeball are differentiated by e.g. different colours.