BOTH-SIDE-TOOTHED BELT

PROBLEM TO BE SOLVED: To improve resistance against bending fatigue of a core code and also improve durability of a belt composed of an externally toothed belt and an interntally toothed belt respectively with equal pitches by enlarging a tooth shape and reducing hardness of one of the toothed belts. SOLUTION: An externally toothed rubber 2 and an internally toothed rubber 3 each toothed with equal pitches are arranged across a core code extended in a longitudinal direction of the belt and with a specified pitch in a widthwise direction of the belt, respectively on its inner and outer circumferential sides. The rubbers 2, 3, are respecively covered with tooth cloths 4, 5. A pitch P1 of the externally toothed rubber 2 is longer than a pitch P2 of the internally toothed rubber 3. The circumferential pitch length is set to be a common multiple of the pitches P1 and P2. A tooth shape of the externally toothed rubber 2 is larger than that of the internally toothed rubber 3, while hardness is smaller in the rubber 2 than in the rubber 3. The externally toothed rubber 2 having large teeth is easily bent along a curvature of a pulley in an arcuate form, and angular phenomena of the core code 1 is prevented.