GB873987A

GB873987A - Two-speed bicycle transmission

Info

Publication number: GB873987A
Application number: GB432158A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-02-10
Filing date: 1958-02-10
Publication date: 1961-08-02

Abstract

873,987. Variable-speed gear. RICHARDS, C. W. Feb. 10, 1958, No. 4321/58. Class 80 (2). A pedal bracket-mounted two-speed gear on a bicycle comprises a ring gear 38, Fig. 1, fast with pedal cranks 13, meshing planet pinions 40 on a carrier 24 formed as a driven sprocket 26a, the planet pinions also meshing a sungear 39 held stationary for a step-down ratio when a ratio selecting clutch disc 44 is slidden leftwards to the position shown so that a ring of holes 75 therein engage teeth 69 fast on a stationary casing 20, movement of the clutch disc 44 rightwards to disengage it from the casing teeth 69 and engage it with clutch teeth 43 on the planet carrier 24 locking-up the gear for direct drive. The sun-gear 39 is rotatably mounted on the spindle 16 of the pedal crank, and is fast for rotation with a similarly shaped gear 45 upon which the ratio selecting clutch disc 44 is in splined engagement. The sungear 39 and the clutch gear 45 form a bearing surface upon which the driven planet carrier 24 rotates. Change of ratio is effected by movement of a handle-bar-mounted selector lever 79, Fig. 15, connected through a cable 78a to one end 87, Fig. 5, of a spring 86, 84 in the form of a bell-crank lever, pivoting about a pin 82, the other end 85 of the spring engaging an axially slidable pin 76 carrying a fork 73 embracing the ratio selecting clutch disc 44. A casing 23, Fig. 1, fast with the planet carrier 24 surrounds the ring gear and contains an absorbent packing 111 which excludes dust and also contains lubricant fed to the gears. The teeth 69, 102, Fig. 12, on the stationary casing 25 and the planet carrier 26, have bevelled edges adapted to co-operate with the holes 75 in the ratio selecting clutch disc 44 in such a manner that if establishment of a ratio shift either up or down is attempted while torque is being transmitted through the gear, the camming action of the bevelled edge upon the edge of the hole 75 will assist the axial movement of the ratio selecting disc.