GB556182A - Electro-magnetically-operated clutches or brakes - Google Patents

Abstract

556,182. Brakes. ROVER CO., Ltd., and IVERSEN, P. A. SCOTT-. April 15, 1942, No. 4938. [Class 103 (i)] [Also in Group XXIV] In an electromagneticallyoperated friction device, e.g. brake or clutch, in which the main frictional engagement is effected at the surface of a non-magnetic frictional material, the magnetic circuit has co-acting parts which are relatively rotatable during engagement but provide no air-gap or only an extremely small one and which can wear at about the same rate as, or at a greater rate than, the rate of wear between the frictional driving surfaces. As shown, a flywheel 11 on a driving shaft 13 has friction plates 21 co-acting with friction plates 22 on a disc 23 on a driven shaft 25. The flywheel 11 carries an electromagnet 17 of magnetic steel the coil 18 of which is positioned by an annular disc 19 of non-magnetic material. The magnet armature comprises a disc 26 fixed to the driven disc 23 and made of magnetic metal powder compressed and/or cemented by a binder so that its surface can wear away by friction when engaged by the adjacent face of the electromagnet. In a modification the electromagnet comprises an annular series of coils and the friction faces are lightly pressed together by springs. In another modification the armature disc 26 is of cast iron and the surface of the magnet has a plurality of files or like abradant members in its surface to ensure that the surface of the armature will be worn down at a greater rate than wear will occur between the non-magnetic friction surfaces.