GB190604639A - Improvements in or relating to Variable Speed Gears and Change Speed Mechanism particularly for Cycles and the like. - Google Patents

Abstract

4639. Blair, W. Feb. 26. Variable-speed gearing; clutches.- Variable-speed gear of the sun-and-planet type for cycles &c. is changed by back-pedalling through an arrangement of pawls engaging ratchet teeth upon the driving- sleeve. Thus, with the parts in the position shown in Fig. 1, pawls P<2>, carried by a freely-mounted sleeve 7, are in engagement with ratchet teeth upon the in ternally-toothed member 3 and with the driving- sleeve 8, so that, the sun-pinion 1 being permanently fixed, the hub is driven at low speed through a friction clutch 10, 11 operated by a screw-thread upon the carrier 4, 5. By back-pedalling slightly, the pawls P<2> are turned out of engagement with the driving-sleeve, while other pawls P<1> are brought into position ready for engagement therewith, so that, on forward-pedalling, drive takes place between the parts 8, 5, and the hub is driven at high speed through a ball clutch 14. Back-pedalling still further brings the parts into such a position that, on forward - pedalling, pawls P<3> drive the hub direct through ratchet teeth 6. To keep the balls 14 out of operation when the hub is being driven at low speed, an extension 3<A> of the part 3 has slots 3<C>, Fig. 2, to receive projections 3<D> upon the ratchet ring 3<B>, so that the initial movement of the ring carries the projections to the ends of the slots, where they hold the clutch balls inoperative until the pressure upon the pedals is relieved, when springs (not shown) return the ring to its normal position, as shown in Fig. 2. A spring 13 tends to keep the parts 10, 11 in contact. To prevent the sleeve 7 from moving in a backward direction when the gear is being changed, a light spring or other brake may be arranged between the hub and the sleeve.; or, as shown in Fig. 4, a spring 7<A> carried by the sleeve may engage the sun-pinion. The balls 14 may be replaced by rocking pawls mounted in the extension 3A, the ring 3B being provided with projections adapted to compress return springs in the extensions and with circular recesses or projections by which the pawls are turned out of operation for the low gear. A ratchet ring engaged by pawls upon the hub may be used instead of the friction clutch 10,11.