GB815053A - Improvements relating to pneumatic vehicle wheel tyres - Google Patents

Abstract

815,053. Pneumatic tyres. PIRELLI S.p.A. Nov. 25, 1955 [Dec. 22, 1954], No. 33859/55. Class 144 (2). A pneumatic tyre, constructed so that creep of the tread against the ground in the flattened ground-contacting region AM<SP>1</SP>B of the tyre is prevented by consequential distortion of the circular arc AB of the tyre to the arc AA<SP>1</SP>B<SP>1</SP>B to maintain a substantially constant peripheral dimension, comprises (a) a carcase of an even number of plies of parallel rubberized textile cords evenly laid in crossed relation in two opposed directions each at an angle of from 50 to 70 degrees to the circumferential, the cords of the plies having an elongation at break exceeding 20 per cent, and (b) a substantially inextensible, flexible, tension-resistant breaker structure of one or more layers of parallel rubberized textile or metal cords of low elastic stretch, the layer or layers being laid with the cords directed at an angle of from 0 to 20 degrees to the circumferential. The cords of the breaker structure may be rubberized with a compound of low modulus of elasticity and a layer or layers of such compound may be interposed between some or all of the carcase plies. The textile composition of the carcase ply cords may be natural, or synthetic such as nylon, and of low modulus of elasticity, or may be of nylon, rayon or cotton, heavily twisted at fine pitch, possibly around a rubber core, to provide the necessary stretch characteristics. The plies of the carcase may be disposed with the cords of adjacent plies crossing, or in bands of two or more plies with the same cord direction, the cords of adjacent bands crossing. The breaker may comprise a single continuous section ring, or a series of spaced side-by-side narrower rings, and where comprising crossed layers, the layers are even in number and disposed evenly in two opposed directions each at an angle not exceeding 20 degrees to the circumferential.