1,039,336. Change-speed gear and control; linkwork. C. SHULER-VOITH, M. VOITH, H. W. SCHWEPPENHAUSER, and C. KNAPP, [trading as VOITH, GETRIEBE KOMM. GES.]. Nov. 7, 1963 [Nov. 7, 1962], No. 44064/63. Headings F2D and F2K. A change-speed gear for motor vehicles &c., has an hydrodynamic torque converter used only in its lowest ratio and ratio shifts are effected under the control of an output speedresponsive governor, a hand-operated forwardreverse lever so actuating a direction control command device that if the lever is operated to change the direction of drive of the vehicle while one or other of the higher ratios is established, the change-speed gear is downshifted to re-establish drive in the lowest ratio before the direction control command device itself moves to establish the reversal of drive. The ratio shifts may be effected hydraulically. Gearing.-An engine 1 drives the ring gear 5 of a front planetary train having planets 7 journalled in a carrier 6 on a shaft 18 driving through a simple forward-reverse countershaft train 38 to an output shaft 37, first ratio being established by hydraulic engagement of a brake 24 to station the ring gear 22 of a rear planetary train having its planet pinions journalled in a carrier 21 also fast on the shaft 18. A splittorque drive is then obtained through the shaft 18, and through a parallel path comprising the planet pinions 7, the sun gear and a one-way clutch 10 in the front train, an hydrodynamic torque converter 13 and the sun gear 19 of the rear train. The torque converter 13 has its blade angle so arranged that the impeller and turbine rotate in opposite directions. Second ratio (all mechanical) is established by disengaging the brake 24 and instead hydraulically engaging a brake 12 to station the carrier of the planets 7 in the front train. Third ratio (direct drive, all mechanical) is established by hydraulic engagement of a multi-disk clutch 44 to lock-up the front train, the one-way clutch 10 overrunning. Forward-reverse shifts in the following countershaft reverse gear are effected by selective energization of two oppositely-disposed servos 42, 43 to slide axially a double-ended friction clutch sleeve 38. Control. Automatic forward shifts.-Forward or reverse drive is established when a handoperated lever 88 is moved from its neutral to its forward (V) or reverse (R) positions and rotates a three-part valve 68, 69, 70 to connect appropriate passages to the ratio establishing clutch and brakes. At engine idle, a centrifugal governor 53, driven through gears 52, 52a from the front planet carrier at a speed proportional to output shaft speed 37, takes the position shown and an engine driven pump 61 supplies main pressure 64, 65 through the valve part 70 to pipes 90, 91 and an open relay valve 92 for engagement of the first ratio brake 24. With increasing speed, the governor 53 opens a pipe 95 to main pressure 65, which in turn opens a relay valve 96 so that main pressure transmitted through a pipe 64, an open relay valve 101 and a pipe 98 is admitted via pipes 99, 100 to the brake 12, which established the second ratio. At the same time, pressure in the pipe 99 closes the open relay valve 92 to disengage the first ratio brake 24. With still further increase in speed, the governor 53 opens a pipe 103 to main pressure which in turn opens a relay valve 104 to admit main pressure in the pipe 98 through a pipe 106 to the lock-up clutch 44. Forward-reverse shift: vehicle stationary.- When the reverse lever 88 is in its central, neutral position, main pressure 65 is connected through the valve part 69 to a control pipe 108, where it closes the relay valve 101 to inhibit establishment of either second or third ratios. In this position of the lever 88, the valve part 70 is closed to prevent main pressure 65 passing through the pipe 90 &c., and prevent engagement of the first ratio brake 24. On moving the lever 88 to, e.g., its reverse (R) position, the vehicle being stationary, first ratio is established in the planetary change-speed gear, as described above. Also, main pressure 65 in the pipe 90 passes through a pipe 109 to a direction control valve 111, movable to two end positions, corresponding to forward and reverse, by liquid pressure acting in spaces 116, 117, a ball detent retaining the control valve in its end positions. Main pressure 65 is now supplied through pipes 118, 119 and the valve part 68 to the space 116, so that the direction control valve 111 is forced down to the R position shown. The main pressure 65 in the pipe 109 is now connected through the control valve 111 to a pipe 120 and thence to the servo 42, which establishes reverse. A similar sequency of movements is effected for establishment of forward drive. Forward-reverse shift: vehicle moving, high ratios established.-When the shift lever 88 is moved from, e.g., forward to reverse while the vehicle is in motion and second or third ratio is established, main pressure 65 is connected through the valve part 70 to the pipe 90 and the pipe 109, through the control valve 111 to a pipe 125, and thence through the valve part 69 to pipes 108b, 108c and the control pipe 108, in which pressure builds up. The direction control valve 111 is at this stage retained in its established position by its ball detent. Control pressure 108 closes the relay valve 101, and shuts off main pressure 64, 65 from the pipe 98 and hence from the second ratio brake 12 and the third ratio clutch 49, which are accordingly disengaged. At the same time, control pressure 108 acts through a pipe 108d upon a piston 144 spring-biased to abut a piston 142, and moves the piston 144 rightwards of the Figure. The piston 142, which is free-floating, follows the piston 144, and thus allows the pressure in a pipe 147 to fall. The pipe 147 is connected to a liquid column 136 between an accelerator pedal 131 actuated master cylinder 133 and a slave unit 137 controlling the fuel supply device 2 of the driving engine 1. Thus the accelerator pedal 131 is now disconnected from the fuel supply device 2, and the engine speed is reduced to idling. As the relay valve 101 has now shut to disengage second and third ratios pressure in the pipe 99 falls and the relay valve 92 re-opens to establish the first ratio. The turbine of the torque converter 13 now brakes the vehicle. So long as either second or third ratio is established, pressure in pipes 127, 128 keeps a relay valve 129 shut, but now that first has been re-established, the governor 53 disconnects the pipes 95, 127, 128 from main pressure 64, the relay valve 129 opens and main pressure 65 passing therethrough to pipes &c., 119, 68, 116 moves the direction control valve 111 to its reverse position. Simultaneously the pipe 109 is connected through the direction control valve 111 to the pipe 120 and the servo 42, so that reverse is established. Closure of the pipe 95 to main pressure by the governor 53 allows the second and third ratio relay valves 96, 104 to be spring- closed, ready for sequential opening as drive is taken up. When the direction control valve 111 moves to its reverse position, supply of main pressure through the pipe &c., 125, 69, 108b to provide control pressure 108 is cut off. An hydraulic accumulator 157 maintains control pressure 108 for a short time, in order to keep the relay valve 101 closed and prevent reestablishment of second or third ratios. The control pressure 108 gradually falls as liquid escapes through bleed holes, and the piston 144 is allowed to move slowly leftwards with the piston 142 and restore pressure in the liquid column 136, re-opening the fuel supply device 2 and connecting the accelerator pedal controlled master cylinder 133 with the fuel control slave unit 137. The engine 1 speeds up, and as drive is restored automatic upshifts to second and then third ratio are established. Forward-reverse shift: low ratio established.- If the vehicle is moving slowly with the accelerator pedal 131 depressed and the low ratio established in the gearing, the pressure in the liquid column 136 and the pipe 147 opens a relay valve 154 to admit main pressure 65 to the relay valve 129, which is thus closed so that the pipe 119 &c., is not connected to main pressure. When the lever 88 is shifted from, e.g., forward to reverse position, pressure in the pipe 125 acts as described above on the piston 144 and causes throttling-down of the engine 1. The relay valve 154 is now spring-biased to its closed position, the relay valve 129 opens, main pressure 65 enters the pipe 119 &c., and the direction control valve 111 moving to its reverse position. The servo 42 is energized, reverse established and the connection between the accelerator pedal actuated master cylinder 133 and the fuel control slave unit 137 is restored. If the accelerator pedal 131 has been released to its idling position when the lever 88 is moved, the establishment of reverse is effected automatically. Modifications.-A one-way valve 152 preventing control pressure 108 acting on the throttle control piston 144 may be replaced by a fourth valve part, Fig. 3 (not shown), actuated by the lever 88 when the latter is set to neutral so as to reduce the pressure in the liquid column 136 and disconnect the accelerator pedal 131 from the fuel control device 2. In this modification, provision is made for the hydraulic accumulator 157 and the throttle control piston 144 to be put in fluid connection through the additional valve part when the lever 88 is turned, so as to throttle down the engine 1 when re-establishing drive. Linkwork.-In a further modification, an accelerator pedal 131a, Fig. 4 (not shown), is connected by links and levers 177, 175, 178 to a cylinder 181 containing a piston 182 normally biased by a spring 183 against an abutment 185 in the cylinder, which then acts with the piston connecting rod 179 as a unitary link. The piston rod 179 is connected through levers &