Patent GB-752082-A (GB)
Title: Gear shifting device for multi-stage change speed gearing, in particular for power driven vehicles
IPC: F16H3/083
Filed: 1953-08-04
Abstract: 752,082. Change-speed gear. GETRAG GETRIEBE - UND ZAHNRADFABRIK GES. Aug. 4, 1953 [Aug. 4, 1952], No. 21490/53. Class 80(2) The change-speed gear of a motorcycle or other vehicle is automatically neutralized by a drive connection introduced between a rotating part of the gear and selector shaft 1 as the vehicle slows to near stopping speed. In Figs. 1 and 2 the drive connection is between an output sleeve 4 and a wheel 3 meshing a wheel 2 on the selector shaft 1, and comprises a single ball 7 in an inclined hole in a ring 9 frictionally mounted on the sleeve 4. At near-stop speeds a spring 8, overcoming centrifugal force which normally holds the ball 7 clear, pushes the ball inwards into a recess 6 in the wheel 3, as shown in the lower half of the Figs. The wheel 3, now driven by the sleeve 4, turns the selector shaft to neutral, in which position flats 10 between two teeth of the wheel 2 push the wheel 3 bodily radially downwards out of the coaxial position on the sleeve 4, permitted by a slotted mounting, which forces the ball 7 out of the recess 6, as shown in the upper half of the Figs., and thus breaks the driving connection. This position is maintained in first speed, but on selecting second or higher ratios, normal teeth of the wheel 2 permit a blade spring 5 to return the wheel 3 to coaxial position. If, during neutralizing, the gear dogs temporarily balk the selector the friction connection to the ring 9 slips. Figs. 3 and 4, not shown, differ in that an opposite movement of the selector shaft is required for downshift, for which purpose a reversing idler is interposed between the wheels 2, 3, the axial centres of which are now invariable and neutral disengagement of the clutch ball 7, which now slides in a radial bore in the friction ring, is effevted by a fixed cam positioned in an annular space between the wheel 3 and sleeve 4. Figs. 5 and 6, not shown, are similar. but disengagement in neutral and first gear is now effected by cutting away two teeth on the selector shaft wheel 2 to break mesh in these positions. Fig. 7 shows the application to a gear in which ratio-selecting clutchballs 20 are clutched outwardly to respective gear-wheels by a cam on an internal axially slidable selector shaft 19. operated through a thrust-race 31 by a lever 30. The neutral shift is effected by a helixsleeve 15, frictionally mounted in the main shaft 14 and having an internal helical groove 16 tracked by spring-loaded halls 18 carried bv the selector shaft 19. Surrounding the thrust-race 31 for free rotation relative to. but axial movement with the selector shaft 19 is a bearing-sleeve 22. prevented from rotation by a fixed kev 25 engaging a groove 24 in the sleeve. Fast on the selector shaft 19 is a block 21. which in second and higher ratio positions. is disposed to the left of the fixed key 25 and carries. in a radial bore. a clutch-ball. 28. which at near-stop speeds. enters the groove 24, thus locking the previously rotating selector shaft 19 to the non- rotating bearing-sleeve 22, so that the balls 18 track along the helical groove 16 of the rotating sleeve 15, screwing the selector shaft 19 rightwards until the clutchball 28 rides up the inclined end of the key 25 to disengage itself from the groove 24, thus disconnecting the selector shaft 19 in the neutral position, shown. At normal operating speeds, the clutch-ball 28 is moving too fast to enter the groove 24. The helix-tracking balls 18 also locate gear positions by engaging circumferential grooves 27 in the sleeve 15. Disengage. ment of the main clutch 29 is effected in any position of the selector by axial move. ment of the stationary end-casing 23, which acts on the clutch 29 through the main shaft 14 which can move through the axially immovable gear wheels.