| 摘要 |
PROBLEM TO BE SOLVED: To provide a transmission hub structure for rotary gear shift of a bicycle. SOLUTION: The transmission hub structure is mainly composed of a hub shaft (axle) 1, a driving element (driver) 2, a hub shell (hub shell), at least one set of planetary gear mechanism 4, a clutch 5 controlling a power transmitting route of the planetary gear mechanism, and a gear shifting mechanism 7 controlling actuation of the clutch. The gear shift mechanism is equipped with a controlling portion 71 for carrying out rotary operation, and attached with that between a transmission hub and a frame rear end. By rotationally operating the controlling portion, the clutch is slid in an axial direction through a cam mechanisms 721, 733, the power transmitting route is switched to shift gear. It is unnecessary to bore a hole on the hub shaft as in a well-known technique, so that the strength and safety of the hub shaft is increased. Furthermore, the controlling portion is installed in the rear end, thereby damages due to external force can be avoided. COPYRIGHT: (C)2005,JPO&NCIPI
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