GB1365927A - Hubgears for pedal driven vehicles - Google Patents

Abstract

1365927 Change-speed gear GAZELLE RIJWIELFABRIEK NV 25 Aug 1971 [1 Sept 1970] 39963/71 Heading F2D A twothree- or four-ratio back-pedalshifted hub gear on a pedal cycle, has means for preventing shift through more than one step at each operation, even when back pedalling is continued indefinitely beyond the minimum required for the shift. Such means is still effective even if a shift is interrupted before completion, by temporary forward pedalling. The shift is established by rotation of a selector cam-shell 27 under the combined control of a one-way coil-spring clutch 35 and a similar detent 43, with lost-motion connections to the input sprocket 3, 4. Gear.-In the three-ratio hub shown, a selector 18 with clutch dogs 20, is rotatable with the input member 3, and, in the axial position shown, is clutched at 20, 21 to a planet-carrier 15 for overdriving the hub 6 through a ring gear 12 and pawls 14. Moved one step axially right, the selector 18, still clutching the carrier 15, strikes off the pawls 13, resulting in direct-drive through previously overrun pawls 16, whilst a further step right clutches the selector 18 to the ring gear 12 for reduced drive through the carrier and pawls 16, reaction being taken by a fixed sun 10. Selection.-The three axial steps of the selector 18 are controlled by followers 19 on the selector, pressed axially right by a spring 38 against a stepped cam profile 26 on a freelymounted cam-shell 27, carried by a sleeve 28, Fig. 4, fixedly mounted on the spindle 1. Between the shell 27 and fixed sleeve 28 is a freely mounted ring 30, connected to the shell through a one-way coil spring clutch 35, and having two radial projections 31, 32, in the path of a radial projection 42 of a stop ring 40, rotating with the input sleeve 3, and two axial projections 33, 34 in the path of the end 44 of a light one-way coil-spring detent 43 on the fixed sleeve 28. The shift sequence obtained by the momentary back pedalling is 1, 2, 3 followed by a return direct from 3 to 1 for repetition of the sequence. The 3 to 1 step may be split into two steps to make a 3-2 shift possible. During forward pedalling, Figs. 7A, 7B, in which the coil spring clutch 35 is represented as a toothed ratchet, the projection 42 on the driven 3 contacts the end 44 to turn the spring detent 43 lightly on the fixed sleeve 28. The selector cam shell 27, loaded axially by the spring 38, Fig. 1, against the stop-ring 40, is carried along frictionally with the driver 3, and, as shown, third ratio is established. To make a shift, in this case from third to first ratio, back pedalling is commenced, and for an idle lost-motion of 120 degrees the cam-shell 27 still moves with the driver 3, without effect, whilst the ring projection 33 leaves the spring end 44, and the opposite ring projection 34 reaches it, causing the coil-spring detent 43 to grip the fixed sleeve 28, to station the ring 30, and, through the ratchet 35, the cam shell 27. Continued back-pedalling now causes the input projection 42 to leave the ring projection 32 and travel as far only as the opposite ring projection 31 (40 degrees), during which travel the selector dogs 19 move into the next notch (first ratio) of the selector cam 26, to complete the shift, but can move no further, any additional back-pedalling merely causing slip of the detent 43.