| 摘要 |
A multi-speed chainless drive mechanism for a cycle-type vehicle comprises a drive shaft rotatably driven by a pedal actuated gear train. The drive shaft, which includes a universal joint, extends away from the gear train. The drive mechanism also comprises a first support provided intermediate the gear train and the universal joint for rotatably supporting the drive shaft to a frame of the vehicle. An elongated shaft extends from the universal joint opposite the gear train. A variable ratio worm gear, more particularly a cone-shaped worm gear, has an opening defined centrally and longitudinally therethrough. The worm gear is slidably mounted on the elongated shaft and is adapted for rotation therewith. The worm gear meshes with a drive gear mounted to a drive wheel of the vehicle. Different gear ratios are thus provided in relation to the longitudinal position of the worm gear on the elongated shaft. The drive mechanism also comprises a year shifting device for moving the worm gear along the elongated shaft and for constantly maintaining the worm gear and the drive gear in a mesh. |
