Patent GB-1452739-A (GB)
Title: Epicyclic change speed gear hubs
IPC: F16H3/46
Filed: 1972-07-15
Abstract: 1452739 Change-speed gear RALEIGH INDUSTRIES Ltd 15 Oct 1973 [15 July 1972] 33218/72 Heading F2D  A three speed back-pedal or manually shifted hub gear for a pedal cycle comprises a drive  input member 11, 13, which in the forward direction, drives a control member 22 selectively connectable to a planet carrier 15 or ring gear 18 by pawls 22a, 22c the engagement of the former being controlled selectively in accordance with the angular position of the input member 11, 13 relative to the control member 22 when the input member is backpedalled, or when relative rotation in the reverse sense is produced by other means. Means is provided to limit the ratio shift to one step irrespective of continuation of back pedalling. The gear is the usual planet gear having a sun 17 integral with the fixed spindle 12, and providing low speed when a ring gear 18 is clutched to input 11, 13, and a planet carrier 15 drives the hub shell 20 at reduced speed through pawls 19; second speed (normal, one-to-one) when the tails of pawls 21d are released to permit the ring gear 18 to drive the hub directly, the pawls 19 overrunning; and high speed when the input is transferred, as described below, to the planet carrier 15 to overdrive the ring gear 18. Pawls 19, 22c are uncontrolled whilst pawls 22a 21d are selectively controlled by back pedal as described below.  In low gear setting shown, forward drive passes from input members 11, 13 (permanently connected by dogs) to the control member 22 through the pivot pins 22h of a pair of pawls 22a the tails 22a' of which engage a pair of relatively shallow recesses 13d, Fig. 5, in the input member .13. Drive passes through the pivot pins 22h to a second set of pawls 22c, engaging ratchet teeth 18c in the ring gear 18, and thence, through the planet carrier 15 and pawls 19 to the hub shell 20.  On back pedalling for 1-2 upshift, the control member 22 is initially held stationary by a drag spring 30 on the fixed spindle 12, and the input member 11, 13 to the extent of a permitted lostmotion (described later) sufficient for the tails 22a' of the pawls 22a to ride out of the recesses 13d into the next pair 13e of still shallow recesses. At the same time a face cam 22l, Fig. 8, on the right end of the control member 22 shifts axially rightwards a cam control member 22d splined on the input member 11, thereby releasing pawls 21d, carried by the ring gear 18, for engagement with ratchet teeth 21c in the hub 20, which, on resumption of forward pedalling, is driven at one-to-one through the control member 22, pawls 22c, ring gear 18 and pawls 21d. On again back pedalling for 2-3 upshift, the pawls 22a ride out of the recesses 13l, Fig. 5, into a third set 13f of deeper recesses, permitting the pawls to engage ratchet teeth 15b in the planet-carrier 15, which, on resumption of forward pedalling, overdrives the ring gear 18, and, through the pawls 21d, the hub 20. The pawls 19 and 22c are overrun. The next back pedal produces a 3-1 shift giving a sequence 1, 2, 3, 1 &c, although by providing a fourth set of recesses such as 13d Fig. 5, the sequence may be 1, 2, 3, 2, 1 &c. The means for limiting gear shift to one step irrespective of continuation of back pedalling is as follows. Between the input and control members 13, 22 is a clutch comprising arcuate pawls 22q, Figs. 1, 4, overlying a flatted part of the input member 13 and carried by a collar 22p, Figs. 1, 3, having a 60 degree arcuate gap 22s receiving the outturned end 22n' of a drag spring 22n on the fixed spindle 12. During back pedalling the clutch parts 22 p, q initially turn freely with the input member to an extent limited by the lost-motion are 22s, whereafter they are arrested by the drag-spring 22n, which causes the flatted end of the input member 13 to expand the pawls 22q into engagement with teeth inside the control member 22 thus locking that member to the input member 13 and preventing any further relative shift movement during continued back pedalling. In Figs. 13 to 15, not shown, the drive between the input member 11, 13 and the control member 22, instead of being transmitted through the tails 22a' of the pawls 22a, passes through a separate ratchet clutch (31) and the pawl tails 22a', now rounded, are operated, on back pedalling, by flats on the input member 13, the flats subtending 60 or 30 degrees, and the ratchet clutch (31) having six or twelve teeth respectively, depending on whether a 60 or 30 degree lost mention is used to make the shift. A back-pedal brake may be provided.