Conical worm gear for a multi-speed bicycle drive mechanism

Abstract From the Canadian patent

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 …