| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic tensioner as an improvement from a conventional one in which the belt load acting on a tension pulley works as an excessive load on a friction board and/or a bushing as a moment to incline along a plane in the offset direction, the bushing is likely to go in partial wear or cracking, arm inclining with respect to a shaft is generated, the belt easily slips off, and/or the swinging motions of the tension pulley encounter any obstacle. SOLUTION: The bushing is formed from a base resin consisting of polyphenylene sulfide of straight chain type, wherein the number mean molecular weight should be 8,000-10,000 g/mol, which is filled with a filler consisting of 15-30 wt.% polytetrafluoroethylene and 5-30 wt.% zinc oxide, and thereby inconvenience due to water absorption inherent in nylon synthetic resin is suppressed to lead to suppression of degradation of the physical and other characteristics, and also abrasive wear can be suppressed.
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