GB599540A - Improvements in electro-magnetically actuated friction clutches and brakes - Google Patents

Abstract

599,540. Friction clutches. CLERK, R. C. Oct. 10, 1945, No. 26522. [Class 80(ii)] [Also in Group XXXIV] An electromagnetically applied friction brake or clutch includes, Fig. 2, an auxiliary brake comprising an annular electromagnet 32 which, when supplied with current through a switch 39 and slip rings 37, 38 is attracted into metal-to-metal frictional engagement with an annular armature 22 secured to a shaft 23. The resulting movement of the electromagnet 32 causes balls 34 in suitably shaped pockets 35, 36, in the electromagnet and in an annular friction disc 28 splined to the shaft 26 respectively, to force the disc 28 axially into frictional engagement with the armature 22 and to force the electromagnet 32 out of engagement with the armature, so frictionally coupling the shafts 26, 23. The movement of the electromagnet 32 is limited by a flange 25 on the shaft 26, and pull-off springs 31 are provided. The disc 28 has a facing 29 of moulded friction material. In another form of the invention, Fig. 1, the ball and shaped pocket coupling 34, 35, 36 between the electromagnet and the friction disc is replaced by a screwthreaded connection between the armature 19 and a friction disc 17 which forces the friction disc 17 into, and the armature 19 out of, engagement with the electromagnet 10 when the electromagnet and the armature come into frictional engagement. A ratchet 21 prevents operation of the screw coupling when braking the shaft 13 from movement opposite to the usual sense. This form of the invention operates as a means of automatically adjusting the brake or clutch for wear. In two other embodiments of the invention, one having a coupling as in Fig. 2 and one a coupling as in Fig. 1 between the electromagnet or the armature and the friction disc, one shaft in the case of a clutch, or the member to be braked in the case of a brake, has two armatures which enclose two friction discs and two electromagnets associated with the other shaft or with the fixed member, and are adapted to make frictional contact with these as in the constructions described. In both of the latter constructions a ball and shaped pocket connection between the annular friction discs and their associated shaft or fixed member provides a selfintensifying action.