Patent GB-786162-A (GB)
IPC: B65H54/64
Abstract: 786,162. Pneumatic tyres. DUNLOP RUBBER CO., Ltd., and TREVASKIS, H. W. Feb. 25, 1955 [March 2, 1954; July 15, 1954; Aug. 17, 1954], Nos. 6023/54; 20636/54 and 23854/54. Classes 144 (1) and 144 (2). A rubber or like pneumatic tyre 3 is reinforced by a cord winding 2 comprising at least one double layer 5 in which the layers cross to form a lattice, and the cord in each layer extends in a series of windings progressing continuously around the tyre in the same direction, each winding being embedded completely in the rubber and consisting of two diametrically opposite arcuate portions, each extending through, and being confined to one bead 7 of the tyre, alternating with portions 10, Fig. 2, which cross the sidewalls and crown in geodesic paths which approach or leave the tyre edges 7 substantially tangentially, the said arcuate edge portions being long enough to ensure that on inflation of the tyre, the tension produced in the cord effects a contraction in diameter of the tyre bead 7 over a major portion of its axial extent to grip a wheel rim. In such a tyre, which may be tubeless and provided with an internal rubber lining 1, the arcuate portions of the cord winding provide an integral tyre bead reinforcement. These arcuate portions subtend an angle # at the tyre centre, Fig. 3, the minimum permissible angle being determined by the stretch characteristics of the cord, which may be of cotton, rayon, nylon or steel. The tyre reinforcement may be wound on a layer of uncured rubber wrapped about a rotatable, collapsible spherical-surfaced former 47, Fig. 10, which is truncated and shaped at opposite ends of a diameter to form axially outwardly flaring circular cord-retaining edges 48, the winding being effected by an arm 53 which rotates about the former 47 on an axis inclined to that of the truncated former, and is geared (56, 50) relatively thereto, to lay the cord substantially about great circles of the former which are progressively slightly displaced and make tangential contact with the circular edges of the spheriel winding surface. As shown, the cord 30 is drawn through a heating and drying unit 32 and a rubber extruder 33 to provide a thin coating of unvulcanized rubber thereon, and thence through a clutch mechanism 34 which ensures a practically constant predetermined winding tension in the cord, irrespective of the tension required to pull the cord through the extruder 33. The cord then passes, via a tension meter 46, through a hollow shaft 52 which is driven by a motor 55 and on the upper end of which is mounted the arm 53, the cord being guided to the end of the arm by pulleys 54. On the completed winding of one or more pairs of crossed layers are wrapped the usual breaker strips, sidewall and tread stock, and chafer strips as desired, and the assembly then removed from the former for shaping in a mould. The shaping process, in which the edges or beads are moved axially inwards and the crown is moved radailly outwards, causes the windings of the cord to be displaced to provide the desired arcuate edge portions connected across the tyre along geodesics which are tangential to said edge portions. Specification 786,165 is referred to.