GB640287A - Improvements in or relating to electromagnetically operated friction couplings - Google Patents

Abstract

640,287. Electromagnetically - operated friction clutches. HOLBERTON, B. V. Sept. 29, 1947, No. 26236. [Class 80(ii)] [Also in Group XXXIV] Electromagnetically - operable friction brakes or clutches comprise a stationary or rotatable electromagnet having an energizing coil 11, Fig. 1, between separate radially spaced annular pole pieces 9, 10 co-acting with relatively slidable armatures 16, 17 so as to draw them together on energization and form a closed magnetic circuit. As shown, applied to a brake in change-speed planetary gearing, the pole piece '9 is secured to a fixed casing 12 and the armatures 16, 17 are carried by a member 6 rotatable on a shaft 7 and carrying an epicyclic element, as an annulus 18, the armature 16 sliding relatively to the member 6 on preferably non-magnetic guide pins 20. Disengaging springs 21 are provided. The pole pieces 9 10 are spaced apart by non- magnetic rings 14 having lugs 14a recessed into the pole faces and secured thereto by non-magnetic rivets 15. Alternatively, the coil 11 may be moulded in place and the rings 14 dispensed with. In a similar clutch, Fig. 3 (not shown), the electromagnet is rotatable, a carrier secured to the outer pole piece being fixed to the central shaft and an additional disengaging spring acting between the carrier and the armature-supporting member. According to the Provisional Specification the carrier may be secured to the inner pole piece, the armature guide pins being then outside the electromagnet, and also, with either a clutch or a brake, the armatures may be independent members. In a modification, armatures 16, 17, Fig. 4, are slidably mounted on a rotatable or, as shown, fixed electromagnet, and grip discs 29, 30 between themselves and the electromagnet.