Patent GB-1389252-A (GB)
Title: Pneumatic tyre
IPC: B60C9/26
Filed: 1972-03-29
Abstract: 1389252 Pneumatic tyres UNIROYAL AG 29 March 1972 [1 April 1971] 14796/72 Heading B7C A pneumatic tyre has a carcass 15, e.g. of radial ply type, and a breaker assembly beneath its tread constituted entirely by a first annular ply structure, e.g. 16, having elongated metallic reinforcing elements and a second annular ply structure, e.g. 17, superimposed on the first, the second ply structure having elongated reinforcing elements all of which are non- metallic and including a strip of material with such elements folded along a circumferential fold, e.g. 23, to form first and second layers, e.g. 21, 24, the first layer being located radially outwardly of, and of no greater width than, the second layer, and the fold being disposed axially outward of one of the axially outermost edges of the first ply structure. In the Fig. 3 embodiment the second ply structure 17 is formed by a single strip folded along two folds 23 such that the first layer has two parts 21, 22 separated from one another in the central region of the breaker assembly by a distance a = 0-0À75 B, where B is as shown. The Fig. 3 embodiment may be modified (Fig. 5, not shown) by folding one edge of the single strip to form a third layer radially inward of the second, the first layer being extended to terminate at the fold forming the third layer or the axially inner edges of the first and third layers being separated in the central region of the breaker assembly by an axial distance = 0-0À75 B. In an alternative embodiment, Fig. 4, the second ply structure comprises two strips 35, 36 located to respective sides of the tyre equator X and each folded about a fold 42, the distance a between the first layers of the strips being 0À6- 0-8 B and the distance b between the second layers of the strips being 0À4-0À65 B. Alternatively, Fig. 6, the second ply structure may comprise a radially inner strip 68, folded about a fold 68b located outward of one edge of the first ply structure to form a radially inner layer 68a and a wider radially outer layer 68c, and a radially outer strip 67, folded about a fold 67b located outward of the other edge of the first ply structure to form a radially inner layer 67c and a narrower radially outer layer 67a. The overall width t of the second ply structure may in all of the above embodiments, be 0À75-0À9 B. In all of the above described embodiments the first ply structure comprises a radially inner layer, e.g. 18, and a radially outer layer, e.g. 19, which may be broader or, as shown, narrower than or of equal width to, the inner layer, the width S 1  of the inner layer being 0À07-0À85 B and the width S 2  of the outer layer being 0À65- 0-85 B. The elongated reinforcing elements of the ply structures may be cords, wires, strips, fibres or filaments and those of the first ply structure may be of steel whilst those of the second ply structure may be of glass or of textile, e.g. cotton, nylon, rayon or polyester. The reinforcing elements of one ply structure may have their longitudinal axes parallel to the circumferential direction whilst those of the other ply structure have their longitudinal axes disposed at 0 to 25 degrees to the circumferential direction. Where the reinforcing elements of a ply structure are disposed at an angle other than 0 degrees the elements of adjacent layers of the structure may cross one another.