Patent GB-568795-A (GB)
Title: Improvements in or relating to brakes, clutches and other frictional devices, including bearings
IPC: F16D69/00
Filed: 1943-04-12
Abstract: 568,795. Clutches. WELLMAN CO., S. K. April 12, 1943, No. 5830. Convention date, May 19, 1942. [Class 80 (ii)] [Also in Groups II and XXXIV] An integral multi-layer structure for friction clutches comprises an outer friction facing of sintered powdered material composed predominantly of high-melting point metal and a backing of metal of high thermal conductivity which by conducting heat parallel to the layers prevents non-uniform heating and thus the warping and cracking thereof. The highlyconducting layer may be such as to constitute also a strengthening backing for the structure or an additional layer of, for example, steel, may be provided for this purpose. A further layer of deformable and good heat conducting metal, in certain cases a heat-insulating layer, may be interposed between the backing and the support to which the structure is secured. A liner for the drum 1, Fig. 2, of an internalexpanding brake comprises a strengthening layer 7 of sheet steel ; a friction layer 8 of sintered copper and/or iron with minor amounts of tin, zinc, lead, graphite and silicon or other abrasive as described in Specification 530,904, [Group XXII]; an intermediate highly-conducting layer 9 of, for example, copper, aluminium, silver, or alloys of copper with silver, chromium or beryllium, but preferably of sintered copper ; and an inner layer 10 of goodconducting metal which is also deformable so as to make good contact with the drum and which may consist of sintered copper with or without tin or of aluminium. The layers may be integrally united by sintering them together, the steel layer 7 being previously electro-plated with copper as described in. Specification 530,904, or the layer 9 may be directly welded to the layer 7. The layer 10 may, however, be separate. The liner 12 for the shoes 2 may be the same as that for the drum with the omission of the layer 10. The shoes may instead have a friction facing of cast iron, steel or moulded asbestos composition. A drum liner is also shown consisting of only a friction layer of sintered material and a backing of thick solid copper. The aeroplane wheel and disc brake shown in Fig. 5 comprises members 49, 50 slidably keyed to the axle 41 by a toothed member 51 and normally urged towards each other by springs 59. The members 49, 50 are movable outwardly to engage liners 58 of asbestos material carried thereby with liners secured to the wheel parts 42a, 42b, of an inflatable rubber tube 53 supplied with fluid through a passage 41a. These liners each comprise a friction layer 46b of sintered material, an intermediate thick layer 46a of solid copper or aluminium and a layer 46c of sintered copper, and are secured to the wheel parts by bolts 47, passing through radial slots in the layer 46a, to allow of expansion. The liners for the members 49, 50 may instead comprise an outer layer of sintered material, an intermediate layer of solid copper and an inner insulating layer of asbestos to protect the rubber tube from excessive heat. A multi-disc wheel brake is also shown in which the annular discs are keyed alternatively to an outer ring bolted to the wheel and to an inner member fixed to the axle, this member carrying an annular piston by which pressure is applied to the discs. Each disc is of steel and has on each side an outer friction layer of sintered material which, for alternate discs, may be mainly copper and mainly iron respectively, and an intermediate layer of sintered copper. Fig. 10 shows a clutch disc comprising a steel disc 83 to which is riveted on each side an integral multi-layer facing comprising outer friction and intermediate highly-conducting layers of sintered material such as described above and an inner steel layer. Between each facing and the disc 83 is disposed a layer of material of low conductivity, such as asbestos. A clutch disc is also shown in which the highly-conducting intermediate layer is directly bonded to a steel disc such as 83. The disc is in this case secured to the hub 80 by bolts that pass through slots in the disc to allow of expansion.