| 摘要 |
PROBLEM TO BE SOLVED: To provide a sound insulating structure for a driving chain, capable of effectively suppressing striking sound-noise generated between the driving chain and a sprocket in a motorcycle. SOLUTION: In order to suppress noise due to contacting-striking sound between a sprocket 10 for transmitting the engine-rotational output to a rear wheel, and an endless driving chain 11 wouned around the sprockets, a ring-like shock absorbing rubber 12 for elastically buffering external force due to meshing load of the driving chain 11 is installed to a double-faced part along the outer peripheral wheel train of the sprocket 10. For the convenience of molding operation, plural through hole 13 are provided at the outer peripheral part of the shock absorbing rubber 12. For the shock absorbing rubber 12, the outside diameter R2 of a part in which the through hole 13 is provided, is formed to be smaller than the outside diameter R1 of a part between the through holes, in which the through hole 13 is not provided, and external force caused by meshing load of the driving chain 11 is first received by the part in which the outside diameter R1 is large, and is then received by the part in which the outside diameter R2 is small with time difference. Thus, the compressibility and the amount of compression are uniform over the whole circumference of the shock absorbing rubber 12.
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