Patent GB-1128359-A (GB)
Title: Clutch facing
IPC: F16D69/02
Filed: 1966-10-19
Abstract: 1,128,359. Friction clutches. RAYBESTOSMANHATTAN Inc. 19 Oct., 1966 [21 Oct., 1965], No. 46723/66. Heading F2C. A motor vehicle clutch friction facing comprises an annular friction element 10 consisting of a spirally wound fibrous fabric strip impregnated with a cement comprising rubber, heat-hardenable resin and friction material filler, and a co-extensive annular reinforcing element 11 comprising a spirally wound strip of thin, flexible, consolidated and condensed dry carded spinning grade asbestos fibre web material of relatively high porosity, the fibres being interlocked with each other, and said reinforcing element strip being impregnated with a cement compatible with that of the element 10 and comprising heat-hardenable resin, the elements 10, 11 being compressed to bond them together and to consolidate the convolutions and heat-treated to harden said cements. As shown, a single reinforcing element 11 is sandwiched between two friction elements 10. The friction element fabric strip may be woven of yarn of asbestos fibres alone or with, e.g., cotton, wool, rayon, linen or jute, and may be reinforced with fine metal wires 16, e.g. of brass, copper, zinc, lead, in the warp 14 and, i desired, also in the weft 15. The Specification includes examples and proportions of natural and synthetic rubbers, resins, and friction material organic or inorganic fillers for the cement with which the woven fabric is impregnated as by passing the fabric through a cement solution and removing excess, as by squeeze rolls. The impregnated fabric is heated to remove solvents without curing the resin. A wide piece of the impregnated fabric may then be wound on a mandrel and subsequently cut into a plurality of coils of desired thickness. The Specification also includes examples and proportions of asbestos fibres and an asbestos fibre/natural and synthetic carrier fibre mixtures for the asbestos web, or a laminate of a plurality of such webs, of the reinforcing element 11, and of glass yarns for an open mesh woven glass fabric reinforcement 17 preferably included in the asbestos web. Such reinforcement may be accomplished by passing asbestos web and glass fabric through rolls causing the asbestos fibres to fill the glass fabric meshes and interlock with one another and with the glass fabric. Preferably the glass fabric is sandwiched between asbestos webs applied to each side. The asbestos web material, glass fabric reinforced or not, may be sized, e.g. by starch, the sizing being so controlled that the web is left in a porous condition. The Specification includes examples of resins for the reinforcing element 11 cement which may also contain natural or synthetic rubber. The material for the reinforcing element 11 may be impregnated, and wound and cut in the manner described for the friction element. The friction and reinforcing element coiled annuli are assembled together and subjected to heat and pressure, e.g. in a mould for densifying, to cause the cements to flow together and permeate the coils and to harden the resin binder and rubber. The resulting clutch facing is then finished, e.g. by surface grinding. Countersunk facing-attachment rivet holes (12) may be formed during moulding, or by subsequent drilling.