Patent GB-910585-A (GB)
Title: Improvements in and relating to automatic variable speed transmissions
IPC: B62M11/14
Filed: 1960-06-24
Abstract: 910,585. Change speed control; positive clutches. NELSON, W. O. June 24, 1960, No. 22197/60. Class 80 (2). A control for a change-speed gear between a driving crank-shaft 14 and a driven sprocket 18 of a bicycle or motor cycle, wherein different ratios are established by selectively clutching pinions 78, 80, 46 to the driving-shaft 14, comprises an output speed responsive governor 116 which preselects a ratio that is established, on reducing the driving torque to zero, by axially sliding a selector sleeve 50 to position clutch pins 54 carried thereby, which pins 54 clutch the selected pinion to the shaft 14. Manuallyoperated over-ride means are provided to lock the selector sleeve 50 in each ratio and the speed at which the governor 116 changes the ratio may be adjusted manually. Clutch and gearing.-The change-speed gear provides direct drive and two over-drive ratios and comprises pinions 70, 72, 74 fast with a counter shaft 66 and which mesh the pinions 78, 80, 46, the latter 46 being fast with the output sprocket 18. The gears 78, 80, 46 are selectively clutched to the shaft 14 by radially outward movement of the clutch pins 54, which movement is effected on limited relative rotation between the sleeve 50 and shaft 14 by cams 58 on the latter. Limited rotation between the sleeve 50 and shaft 14 is permitted by pins 222 fast with the latter which engage circumferential slots 224 in the former. When drive torque is zero the pins 222 are held centrally in the slots by leaf-springs 226 which thus disengage the clutch 54. Governor and operation.-The speed-responsive governor comprises centrifugal masses 116 attached to leaf-springs 106 connected between a member 96, which is frictionally driven at a speed proportional to the output speed, and the outer races of a thrust ring 90 the inner race of which is integral with a sleeve 82. As the output speed increases the centrifugal masses 116 act to pull the sleeve 82 left against a return spring 112 which leftward movement acts through rods 122 to compress springs 124, the selector sleeve 50 being held stationary by a spring detent 230 fast with the shaft 14. At a predetermined output speed an extension 84 of the sleeve 82 engages a projection 242 on the spring detent 230 to depress the latter so that when the driving torque is removed to align the spring detent 230 with a recess 250 in the end plate 126 of the selector sleeve 50, the recesses pass over the detent and the selector sleeve is moved by the springs 124 to the next ratio position which is determined by the plate 126 abutting a second spring detent 232 (Fig. 9). Further increase of speed moves the sleeve 82 further left until the detent 232 is depressed whereupon, on removal of input torque, the selector sleeve is moved to high ratio position as above described. On decrease of output speed the springs 112 move right the sleeve 82 which through rods 129 compress the springs 124, the selector sleeve being held by the detent 232 until the extension 84 depresses the detent, whereupon on removal of input torque the springs 124 shift the selector sleeve to a lower gear ratio position wherein the sleeve is held by the detent 230. Further decrease of speed shifts the gear to low ratio in a similar manner. The initial compression of springs 112 may be adjusted, to change the speed at which the shifts occur, by turning a knob 146 fast with a shaft 144 which has a helical groove 152 in which engages a pin 156 fast with a seat 114 of the spring 112. Manual override.-The gear may be locked in any ratio by selectively moving down latch plates 180 to engage a groove in the selector sleeve 50 and prevent movement of the latter. A projection 176 on a manually operable slide 174 acts through pins 184, 186 or 188 to depress the selected latch plate against the action of return springs.