Patent GB-1199846-A (GB)
Title: Gear Box Controls
Inventor: PAGE WILBUR MILLS
IPC: F16H59/04
Filed: 1968-07-03
Abstract: 1,199,846. Change-speed control. CLAYTON DEWANDRE CO. Ltd. 3 July, 1969 [3 July, 1968], No. 31777/68. Heading F2D. An hydraulic or, as shown, pneumatically operated shift mechanism for a gear-box (not shown) providing six forward ratios and one reverse comprises a universally mounted shift lever 12 movable in a slotted gate 11 for selectively operating, through cam-operated plungers, a group of valves 27, 46, 58 controlling one or more pneumatically-operated ratio-selecting and establishing servo-motors (not shown) which maybe of the type illustrated in Specification 1,199,847. As shown, the shift lever 12 has a forked end 14 mounted on a pin 15 transversely passing through a pivotally mounted shaft 17 and surrounding sleeve 16 formed with valve actuating cams 21, 22 and a centre cam detent 23 which co-operates with a spring- loaded roller plunger 35 for maintaining the shift lever 12 in any ratio established position. A yoke 19 is pivotally mounted on trunnions 20 and has valve-actuating cams 41, 42 which together with the cams 21, 22 on the sleeve 16 engage rollers 24, 43, 55 of spring-loaded plungers 26, 45, 57, downward movement of each of which initially closes the appropriate valve and associated port from a pneumatic manifold 40, connected to an inlet port C, and then exhausts the port. With the shift lever 12 positioned in the central neutral gate slot 11 opposite the 1st and 2nd ratio positions, all the valves leading to ports A, B, D and M (connected to the appropriate gear-selecting servo-motors) are closed, i.e. connected to exhaust port E, the cams 21, 22, of sleeve 16, bearing on rollers 24 to close valves 27 and unseat valve discs 31, and the cams 41, 42 on yoke 19, bearing on rollers 43, 55 to close valves 46, 58 and unseat valve discs 49, 61. Movement of the shift lever into 1st causes the cam 22 to move away from the rollers 24 whereby the valve 27 is spring-returned to open, i.e. re-connect it to the manifold 40 and cut off its exhaust to port E from the valve port M whereby the port M charges, via a line, a pneumatic-servo (not shown) for selection of 1st gear, the shift lever being retained in this position by the spring-urged roller 35 engaging a dwell in the cam detent 23. Movement of the shift lever into 2nd causes the cam 21 to similarly operate, as above, its respective roller and valve (not shown) and port D is closed to exhaust and opened to the inlet manifold 40 similarly to the above operation of port M, whilst simultaneously the cam 22 again depresses the valve 27 whereby the valve port M is cut off from the inlet and re-connected to exhaust port E, whereby port D charges, via a separate line, the pneumatic servo for selection of 2nd gear. Returning the shift lever to the central neutral slot 11 between the 1st and 2nd ratio positions cuts off port D from the manifold pressure source 40 and again connects it to exhaust port E. Movement of the lever 12 along the slot 11 to a position between 3rd and 4th ratio positions rocks the yoke 19 on its trunnions 20 so that its cam 42 is moved away from the roller 55 whereby the valve 58 is spring- returned to open, i.e. connect it to the manifold 40 and cut off its exhaust to port E from the valve port B whereby the port B charges, via a fluid line, the or a second pneumatic servo (not shown) in preparation for movement of the shift lever into 3rd and 4th positions of the gate similarly to actuate the valves 27 controlling the ports M and D as for the 1st and 2nd gear-shifts. Further movement of the lever 12 along slot 11 to the position between 5th and 6th ratio positions further rocks the yoke 19 so that its cam 41 is moved away from the roller 43 whilst the cam 42 again depresses the roller plunger 55 whereby the valve port A is pressurized and the port B is exhausted such that the port A charges, via a fluid line, the or the second servo in preparation for movement of the shift lever into 5th or 6th positions to again similarly actuate the valves 27 of ports D and M for 5th and 6th gear establishment, respectively. Still further movement of the lever 12 along slot 11 to the position facing reverse ratio rocks the yoke 19 to move both cams 41, 42 away from the rollers 43, 55 so that both valve ports A and B are pressurized in preparation for movement of the lever into reverse to effectively connect port D to pressure similarly as for the selection of 2nd, 4th and 5th ratios. Unintentional engagement of reverse is prevented by a baulk 7 on the casing until a spring-loaded sleeve 8 on the lever 12 is lifted to clear the baulk 7. Also the lever 12 is centrally biased away from at least one end of the neutral slot 11 adjacent 1st and 2nd ratio positions by a spring-loaded plunger 72 arranged to engage a roller 74 carried by the yoke 19, two such plungers of which may engage each side of the yoke 19 to centrally bias the lever 12 in the neutral slot 11.