Patent GB-796977-A (GB)
Title: Two-speed coaster brake for bicycles and the like
IPC: B62L5/08
Filed: 1956-04-27
Abstract: 796,977. Coaster hubs. BENDIX AVIATION CORPORATION. April 27, 1956 [May 19, 1955], No. 13048/56. Class 136(2) [Also in Group XXIV] A two-speed gear and a brake in the hub of a bicycle or the like are both operated by back-pedalling. A driving sprocket 63 is fast with an internally and externally threaded high speed driving sleeve 18 mounted upon an externally threaded low speed driving sleeve 7 journalled upon a non-rotary axle 1. The high speed sleeve 18 carries on its external thread a coned friction clutch member 43 which can be engaged with a corresponding surface 27 on the inside of a driven wheel hub 22. The low speed sleeve 7 is fast with a planet carrier 15 the planet gears 9 of which mesh internal teeth 11 on the driving member and non-rotary sun gear 12. A low speed coned friction clutch member 35 is mounted on the threads of the low speed sleeve 7 and can be engaged with a surface 26 on the wheel hub 22. In the position shown in Fig. 1, the high speed clutch member 43 is engaged with the wheel hub 22 for direct drive, and the planet carrier 15 sleeve 7 &c. rotate freely. To change to the lower ratio, the bicyclist, &c., stops pedalling, the continuing forward motion of the bicycle, &c., screwing the high speed clutch member 43 to the right on the threads of the sleeve 18 to its disengaged position. On momentarily back-pedalling, the high speed clutch member 43 is screwed off the ends of the threads on the sleeve 18 on to an unthreaded portion 47, and turned relatively thereto. The left hand end of the clutch member 43 is provided with recesses 52, 53 which for direct drive are engaged by projections 49, 51 on a ring 48 fast with the high speed sleeve 22. Having back-pedalled to turn the clutch member 43 relative to the high speed sleeve, when forward pedalling is recommenced the projections 49, 51 are unable to re-enter the recesses 52, 53 and the clutch member 43 thereby is prevented from re-engaging with the hub 22. A spring washer 59 presses a clutch ring 54 splined on the low speed drive shaft 7 to engage its facial teeth 57 with corresponding facial teeth at the right hand end of the clutch member 43, so that the latter may be turned with respect to the high speed sleeve 18. When forward movement of the pedal is resumed, the driving member rotates the low speed sleeve 7 at a reduced ratio by means of the planet gearing, and as soon as the speed of the low speed sleeve 7 exceeds that of the driven hub 22, the light friction drive of a drag ring 41 causes the clutch member 35 to be drawn into frictional engagement with the driven hub 22. Shifting back into direct drive is accomplished in the same way, by backpedalling to disengage the low speed clutch member 35 from the hub 22 and to turn the high speed clutch member 43 relatively to its screwed hub, so that the projections 51, 49 on the ring 48 can again enter the recesses 52, 53 in the clutch member. The drag ring 45 provides the necessary light friction drive to screw the clutch member into engagement with the wheel hub when forward pedalling is again resumed. If back-pedalling is continued beyond the point required to change speed, the low speed driving clutch member 35 is traversed to the right, compressing a spring 38 and bringing teeth on the clutch member into engagement with teeth 37 of an expander ring 32. Segmental brake shoes 28 are thereby engaged with the inside of the hub 22. Specification 772,396 [Group XXIV] is referred to.