GB630129A - Improvements in and relating to combined variable speed hub gears for vehicle wheels - Google Patents

Abstract

630,129. Change-speed gearing. BURGESS, A. F. (Buchmann, A.). March 20, 1946, No. 8639. [Class 80 (ii)] In an epicyclic variable-speed gear contained in the hub 2 of a bicycle, the planet cage 14 has an extension which forms the inner member of a jamming roller back pedalling brake, the rollers 23 splaying open a fixed brake ring 24 which bears against a rotating part of the hub. The epicyclic gear, which comprises a fixed sun wheel 12, planets 13 and an annulus 15, is of known type where a cruciform member 10 is axially slideable to couple the planet cage, the annulus, and the annulus and ratchet mechanism 17 with a driving member 9, for high, medium and low speeds respectively. The planet cage 14 has an extension which is formed with inclined curved surfaces 22 on which bear the rollers 23 carried in a cage 30 which, when the planet cage rotates in a backward direction through back pedalling, ride up the inclines and splay open a brake band 24 which bears against a liner 29 in the light alloy hub shell 2. As pedalling has ceased before the planet cage commences to reverse its rotation, the pawl 33 of the freewheel connected therewith is pressed inwardly by the overrunning of the ratchet 34 and thus the extension 40 of the roller cage 30 can move over the pawl to hold it out of engagement until forward pedalling is resumed. When the bicycle is wheeled backwards the planet carrier tends to rotate backwards and thus operate the jamming roller brake, movement of the rollers however, rotate the cage 30 to allow end 40 of the slot 32 in the cage to co-operate with the cam 39 on the pawl 33 to hold the latter engaged with the ratchet 34 and thus the hub shell and the planet carrier rotate at equal speeds and the brake is not energised. To ensure the correct location of the roller cage 30 on assembly, the planet cage is provided with a pin 43 which co-operates with a slot 42 in the roller cage.