Variable speed transmission comprising variable eccentricity one way gearing and planetary gearing

摘要

A variable speed transmission, primarily for a cycle hub gear, comprises a variable-stage (18) and a planetary stage (14). The planetary stage has a sun gear (13) driven directly by a rotational input from the chain sprocket (12) of the cycle and a ring gear (17) responsive to added motion provided at the output (32) of the variable stage (18). The variable stage (18) includes ratchet gearing (24) mounted on a fixed carrier (23) and rocked sequentially by integral followers (22) cooperating with a cam track (21) of a circular eccentric cam (20) which rotates with the input drive. The arrangement is capable of providing an output drive to the hub (10) which is geared upwardly or downwardly from the chain sprocket input drive by selectively varying the eccentricity of the cam (20). IMAGE