Stepless speed change device

Abstract

A stepless speed change device comprises internally toothed ratchet rings arranged in plural rows side by side in an axial direction on an inner circumference of a driving rotary member on an input side through one-way clutches interposed therebetween, a stationary ring fixed to a frame of a bicycle and encircling the driving rotary member, a plurality of planet rollers rotatably fitted in the driving rotary member at plural locations, pawls in plural rows to engage ratchets of the internally toothed ratchet rings and having bottoms pivotally connected to an eccentric cam whose eccentricity relative to a center shaft is adjustable, and a resilient member provided in contact with the planet rollers to produce the frictional transmission between the stationary ring and the internally toothed ratchet rings respectively and the planet rollers. When the driving rotary member is being rotated the planet rollers are revolved together with the driving rotary member and at the same time are rotated about their axes with the aid of the frictional transmission and the internally toothed ratchet rings are rotated by the planet rollers with the aid of the frictional transmission.