GB951018A - Improvements in or relating to two-speed hubs - Google Patents

Abstract

951,018. Change-speed gear; ratchet clutches. FICHTEL & SACHS A.G. July 10, 1962 [July 13, 1961], No. 26563/62. Headings F2C and F2D. A two-speed planetary gear hub for bicycles has its ratios selected by back-pedalling to turn two multiply-toothed cam members, spring-biased axially together, relatively to one another, so that one shifts axially with respect to the other, to select a new ratio. In one form, a driving sprocket 1, Fig. 1, and an input carrier 2 mount planet pinions 4 meshing a fixed sun gear 5 and a driven ring gear 7, a ratio-shift multiple tooth system 8 on the latter meshing a ratio-shift multiple tooth system 9 on a ring 11, the latter carrying spring-biased pawls which can mesh with ratchet teeth 13 on a sleeve 14 connected by a lost-motion coupling 15 to a driven hub 16. In the position shown in Fig. 1, the ratio-shift tooth systems 8, 9 coact as illustrated in Fig. 5 due to the bias of a spring 33, and a step-up drive passes through the planetary gearing to the ring 11, its pawls, the ratchet teeth 13 and thence to the hub 16. A backpedal brake cone 24, mounted by screw-threads 31 on a sleeve 29 having a toothed connection 55 with the input planet carrier 2, carries pawls (not shown) which during step-up drive -ratchet freely over teeth 19 in the hub 16, and also carries a friction ratchet clutch spring 22 engaging a groove 23 in the ring 11 but allowing the latter to rotate freely in the forward direction. To change the ratio, the input carrier 2 is momentarily reversed by back-pedalling. The ratchet clutch spring 23 holds the ring 11 and tooth system 9 from turning backwards, while the ring gear 7 and tooth system 8 are turned reversely with the input carrier, so that the ring 11 is slidden leftwards of Fig. 1 against the bias of the spring 33, and the tooth systems take up the position shown in Fig. 6. Teeth 10 of the tooth system 9 engage behind notches 58 of teeth 20 of the tooth system 8, to hold the ring 11 in its leftwards position. The pawls (not shown) on the ring 11 are slidden along inside the hub 16 by the movement of the ring 11, over a cam surface 66 which disengages them from the ratchet teeth 13, to a position where they slide freely over a cylindrical surface within the sleeve 14, Fig. 2 (not shown). On resuming forward pedalling, a direct drive from the input carrier 2 is obtained through the sleeve 29, the brake member 24 and the pawls (not shown) carried thereby, the ratchet teeth 19 and the hub 16. The step-up drive can be re-established by a further momentary back-pedalling. A friction ring and spring 17, 18 between the ring gear 7 and the sleeve 14, in conjunction with the lost-motion coupling 15, prevents jamming of the brake when, with the gear in the step-up drive condition of Fig. 1, the bicycle is wheeled backwards following braking, by allowing the pawls on the brake member 24 to engage and screw the latter to its disengaged position. In one modification, Fig. 7 (not shown), pawls mounted on the ring gear always mesh with ratchet teeth in a ring selectively clutched to the hub by a positive clutch ring slidden axially on relative rotation of the two tooth systems, the clutch ring being carried by a ring in turn carried by a mounting ring formed with the tooth system 9. In another modification, Fig. 8 (not shown), a pawl carrier is separate from the ring gear and is carried by a shift ring formed with the tooth system 9, clutch teeth between the pawl carrier and the shift ring being selectively engaged and disengaged by relative rotation of the two tooth systems. In another form, Fig. 9 (not shown), the back-pedalling brake is replaced by a device preventing unlimited back-pedalling. In another modification, Fig. 10 (not shown), the two ratio-shift tooth systems are associated with the planet carrier, instead of with the ring gear. In a construction giving direct drive and a reduced ratio, Fig. 11 (not shown), the ratioshift tooth systems are located between the ring gear and the pawl carrier, which is slidden to disengage its pawls from the associated ratchet teeth. Another construction also giving direct and step-down ratios, Fig. 12 (not shown), has the ratio shift tooth system between the planet carrier and a control sleeve on which is mounted a pawl carrier. Other modifications are envisaged having clutch means between a ratchet toothed ring and the hub shell with the ratio shift teeth on the planet carrier or the ring gear, or a clutch between the planet gearing and an output member, with the ratio shift toothed gear systems on either the ring gear or the planet carrier.