Improvements in pneumatic tyres

摘要

747,452. Pnumatic tyres. UNITED STATES RUBBER CO. April 26, 1954 [July 15, 1953], No. 11936/54. Class 144 (2). To reduce growth and groove cracking in a tyre comprising a carcase 7 of rubberized nylon cords 9 having a ten-pound stretch of from 10 to 15 per cent, a breaker strip 12 of rayon cords having a ten-pound stretch of from 5 per cent to 8 per cent is interposed between the rubber tread 2 and the carcase 7. As shown two superimposed breaker strips are employed the rayon cords of which are oppositely angularly disposed at a crown angle of from 1 degree to 3 degrees higher than that of the nylon carcase cords, which latter may be in the range of from 30 degrees to 40 degrees. The carcase nylon cords (usually plied yarns) have a low modulus of elasticity, generally from 2 to 5 x 1010 dynes/cm.2, whereas the rayon cords of the breaker plies have a high modulus of elasticity of from 8 to 25 Î 1010 dynes/cm.2 or even higher. Reference has been directed by the Comptroller to Specification 712,384.