GB853203A - Improvements in or relating to electromagnetic devices for conveying or restraining rotary motion - Google Patents

Abstract

853,203. Friction clutches. POWNALL, G. N. DU T. Oct. 8, 1958 [Oct. 8, 1957], No. 31390/57. Class 80 (2). [Also in Groups XXXII and XXXIV] A main friction clutch, brake, or damper, comprising plates 45, 42 respectively splined to a driving or stationary housing 10 and a hub 23 fast on a driven or braked shaft 12, is engaged when a winding 17 is energized to engage a pilot electromagnetic friction clutch or brake 15, 57 between the housing 10 and a cam sleeve 59 rotatable and slidable on the shaft 12 to actuate a presser plate 41 through the sleeve 59, facial cam surfaces 60, a follower sleeve 62 axially slidable in the hub 23 by means of pins 63, a spherically seated thrust ring 65 and levers 51 pivoted on the hub 23. In operation, when the winding 17 is first energized, the armature 57 is drawn into contact with an asbestos friction washer 20 protruding from the element 15, which washer determines the minimum air gap, and is thereby rotated relatively to the follower sleeve 62 until clearance between the plates 45 and 42 is taken up, the air gap being automatically adjusted to an optimum width by.reactionary movement of the cam sleeve 59. A spring-loaded radial detent 54 carried by the hub 23 then engages serrations 55 on the cam sleeve 59 to circumferentially detain the sleeves 59, 62, with respect to each other, in the position reached as a result of said reactionary movement so that upon de-energization and subsequent energization of the winding 17 plates 45, 42 are respectively unloaded and loaded without relative rotation of the sleeves 59, 62 until such time that plate wear again permits contact of the armature 57 with the washer 20. The device may be used as a damper for vehicle suspensions, the housing 10 being fixed to the vehicle frame and an arm of the shaft 12 being linked, to a sprung axle. In such an arrangement the plates 45, 42 may be constantly spring loaded and the electromagnetic loading may be applied at will, when supplementary torque resistance is required, or during rebound periods.