GB779159A - Improvements in or relating to pneumatic tyres - Google Patents

Abstract

779,159. Pneumatic tyres. DUNLOP RUBBER CO., Ltd. May 12, 1955 [June 29, 1954], No. 18986/54. Addition to 731,286. Class 144 (2). A pneumatic tyre has a breaker strip, between the tread and the carcase, which comprises a series of contiguous, overlapping, uniformly circumferentially displaced convolutions 2 of inextensible rubber-coated filamentary material (metal, cotton, silk, flax, rayon, nylon or the like), each convolution including two straight lengths 2a, 2b which meet at, and are oppositely inclined to, the mid-circumferential plane of the tyre. Fig. 1 shows the convolutions each completed by a length 2c which is inclined to the mid-circumferential plane at an angle less than 90 degrees but not less than 55 degrees and which forms a triangle with the lengths 2a, 2b. Alternatively, the convolutions may be of diamond shape, Fig. 4, with sides 4a, 4b, 4c, 4d and of greater circumferential length than transverse width. This arrangement may be combined with an additional layer or strip of a zig-zag winding 5, the lengths 6a, 6b of which are inclined to the mid-circumferential plane at an angle of 84 degrees. Alternatively the diamond arrangement may be modified by a winding which provides two parallel lengths 3c, 3d, Fig. 2, in each convolution, which are normal to the mid-circumferential plane and form a transverse diagonal of the diamond. In all cases, the apex angles at the mid plane are generally in the range of 20 to 30 degrees. The complete strip may comprise a single winding to leave two free ends only, or may comprise two or more shorter windings overlapped at their ends. Two strips may be superposed to provide two layers with corresponding parts of the convolutions in the respective layers crossing each other. Where metal wires are used, the wire is embedded in a soft rubber compound for cushioning purposes.