Patent GB-190417588-A (GB)
Title: Improvements in Two Speed Gearing for Bicycles and other Vehicles
Inventor: THOMPSON CHARLES SOUTHARD
Filed: 1904-08-12
Granted: 1905-01-26
Abstract: 17,588. Thompson, C. S., and Maynes, H. F. Sept. 2, A.D. 1903, [date applied for under Patents Act, A.D. 1901]. Driving mechanism ; clutches ; brakes.-Relates to a two-speed driving-gear for bicycles and other vehicles, in which the changes of speed are effected by back-pedalling ; a brake, operated by a still further backward rotation of the driving-wheel, is also described. The gear is so constructed as to be applicable to chain - driven bicycles or to machines driven by bevel-gear. As shown, a ball clutch 19 is in operative position, the balls 20 of the low-speed clutch being within pockets in a sleeve 5, and power applied to the driving-member 7 turns the sleeve 5, so that planet-wheels 17, moving around a stationary wheel 16, impart motion to a gear-ring 14 and a high-speed sleeve 12. The clutch 19 locks this sleeve to the hub 3. A slight backward rotation of the cranks moves the low-speed sleeve until a pawl 34, Fig. 2, engages the front of a slot 36. During this motion, the sleeve 39 of a clutch controller, which is formed by the parts 39, 41 connected together by a channel ring 40 carried by the sleeve 39, is moved backwards with the lowspeed sleeve, while a ratchet-ring 38 is held stationary by the pawl. This pawl is locked by a clutch 23, 21, for a lug 31, Fig. 6, upon a pawl-carrier 30, tending to ride up a notch 32 upon the loose member 21, forces this member into engagement with the fixed part and so holds the parts against movement. The sleeve 39 will thus be moved with respect to the ratchet - ring through a distance equal to that between notches 45, 46, Fig. 5, on the sleeve, so that teeth 48 on the ratchetring are moved into engagement with notches 46, and, assisted by a spring 44, the part 41 is forced towards the high-speed clutch, its fingers 42, retaining the balls within their pockets in the high-speed sleeve and so keeping the clutch out of action. The change of gear has now been effected, and, upon forward movement of the sprocket-wheel, the sleeve 39, through teeth 40', is moved forwards with the low-speed sleeve, and through teeth 48, carries round the ratchet-ring until the next tooth is brought into engagement with the pawl 34, which, now picked up by the rear wall of the slot 36, once more turns the pawl-carrier, releasing the loose clutch member. Driving is now effected directly through the lowspeed clutch. When the high-speed gear is in operation, the clutch 20 is over-ridden and is rendered inoperative. By a similar back-pedalling motion, the teeth 48 are brought into engagement with the notches 45, when the endwise motion of the controller due to the cam-surface 47 releases the high-speed clutch balls and brings the highspeed gear again into effect. If the pedals be turned backwards to a greater extent than that necessary to change the gear, the tooth 31 of the pawl-carrier, first effecting the engagement of the clutch, now rides over into a notch 33, when the parts may be freely rotated backwards. This causes teeth 57, Fig. 8, upon a ring 58 to engage two cam-surfaces 56 upon a ring 55, so that this ring and a ring 53 are forced towards the right. Cam-projections 54, Fig. 7. between the tapered ends of the brake shoes 52 are thus caused to expand these members, so that they frictionally engage the hub and act as a brake, the brake shoes being prevented from rotating by lugs 59 upon a fixed plate 50. Forward movement of the pedals allows the rings 55, 53 to move towards the ring 58, when a spring 60 surrounding the brake shoes draws these members together, and the brake is released. At the same time, the part 21 of the clutch, first forced inwardly by the ascent of the tooth 31 up the cam-surface between the notches and so held stationary, is released when the tooth passes back into the notch 32, and the parts resume their normal positions. Considerable play is left between the projections 56, 57, so that back-pedalling movement to change the gear does not effect the brake mechanism.