GB418716A - Change speed gearing - Google Patents

Abstract

418,716. Change-speed gearing. LUNDQVIST, G. F., 126, Folkungagatan, Stockholm. Feb. 5, 1934, No. 3679. [Class 80 (ii).] The speed is changed in two-speed epicyclic gearing in a casing 79, Fig. 12, each time a driving crank 78 is displaced backwards. A one-way brake 81 prevents a windlass drum 73 from turning backwards in speed changing. In the applications to bicycles shown in detail in the other Figures, there is on the rear axle, not shown, in addition to the one-way brake, a free-wheel to allow the cycle to run on. Rearward displacement of a pedal crank 2a from position A, Fig. 3, to position B changes each time the position of a double-acting pawl 36 which changes between solid and reduced drives and back again in succession. The driving direction is clockwise. The pawl 36 turns stiffly on the end of a planet spindle 26, Fig. 1, so as to engage with a central disc 19 on the driving crank axle 1 for solid driving, or with a stop on a fixed annulus 42 for geared drive. A planet - carrier 27, which is thus clutchable solid or holdable against rotation, supports stepped planets 24, 25 meshing respectively with a sun pinion 18 fast on the axle 1 and with a larger sun pinion 22 rigid with the usual sprocket wheel 9. Fig. 3 shows the position of the pawl 36 on solid drive engaging a recess 40 in the disc 19. To change speed, the rider moves his foot rearwardly from its lowest position to move the crank 2a from A to B. The pinion 18 moves back, the pinion 22 is held fast by the said one-way brake, and the planet group pivots about its line of engagement with the pinion 22 so that the pawl 36 is carried forwardly or clockwise to the position of Fig. 5 in which the pawl 36 has been lifted out of the recess 40. On resuming pedal driving, the pawl 36 shoots past the recess 40, as it is free to do, and glides along a pivoted cam plate 46. As the pawl 36 approaches the position of Fig. 6, engagement with the edge of the disc 19 causes it to tilt the plate 46 clockwise and so compress a spring 47. The pawl 36 on engaging an abutment 42b stops the planet carrier 27 so that the gearing becomes operative on reduced drive. On repeating the rearward crank displacement from A to B, Fig. 3, the recess 40 and the pawl 36 turn towards one another and the spring 47 causes the latter to snap into the former. Resumed pedal drive is then solid in high gear. Figs. 7 and 10 show an arrangement in which the geared drive is an overdrive. The planet carrier 58 is in this case fast on the driving crank axle 1. The larger sun 51 is rigid with the driven sprocket 9, and the smaller sun 50 by a flange 52 and pivot 54 carries the doubleacting pawl 53. When the pawl 53 engages a recess 40 in a flange 58e on the carrier 58, as shown in Fig. 10, solid driving results. When the pawl 53 is in the position shown relatively to the fixed annulus 42 and to a spring-pressed plate 65, the crank 2a is in an inclined position A<1>. To change speed, the pedalling is continued to the bottom position A, which brings the pawl to position 53a. The crank 2a is then displaced rearwardly to position B. This brings the pawl to position 53a<1> where it is out of the recess 40. Forward pedalling then brings the pawl to position 53a<2> where it is stopped at 42b so that the geared overdrive becomes operative. On the change back to solid drive, the plate 65 pushes the pawl down into the recess 40. The double-acting pawl may be arranged to slide instead of to pivot.