| 摘要 |
831,254. Tyre treads. UNITED STATES RUBBER CO. Sept. 27, 1957 [Nov: 23, 1956], No. 30351/57. Class 144 (2). A pneumatic tyre tread 11 is provided throughout its circumference with circumferentially spaced radially inwardly extending slits 17 forming a plurality of groups of tread segments, each group comprising at least one major segment 15 and at least one minor segment 16 with the length of the minor segment being determined by slits spaced within the range 4 to 9 slits per inch and the major segment being not greater than ten times the length of the minor segment. The ratio of the number of minor segments to the number of major segments in the tread may range from 1 : 2 to 7 : 1. The tread may comprise shoulder ribs 13, a central circumferential rib 12 and intermediate circumferential ribs 14, the slits 17 extending to a greater depth in the shoulder ribs 13 than in the ribs 12, 14, as shown, or vice versa, or being of equal depth in all the ribs. Alternatively the depths of alternate slits in each rib may be equal. The major segment length may be 0.6 to 1.2 times the depth of the grooves between the tread ribs, and the minor segment length may be 0.5 to 0.1 times the major segment length. Specifications 198,79t, 449,136, 547,121, 677,400 and 724,210 are referred to.
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