Patent GB-864409-A (GB)
Title: A semi-automatic gear-changing device
Filed: 1959-01-23
Abstract: 864,409. Change-speed and clutch control. AUTOMOBILOVE ZAVODY NARODNI PODNIK. Jan. 23, 1959 [Feb. 10, 1958], No. 2591/59. Class 80 (2). Change-speed control mechanism for a motor car, having a main clutch E, Fig. 1, and changespeed gears 4, 4<SP>1</SP> together with a sliding reverse wheel 5, comprises a manually operated ratio selecting lever or press buttons (not further described) actuating control slides 10, 10<SP>1</SP>, 10<SP>z</SP> upon which are mounted levers 12, 12<SP>1</SP>, 12<SP>z</SP> each connected at one end to a sliding control valve B, B<SP>1</SP>, B<SP>z</SP>, respectively and at the other to the sliding rod of a double-acting ratio establishing servomotor A, A<SP>1</SP>, A<SP>z</SP>. Each of the sliding servomotor rods is retained in a ratio established or neutral position by a spring-biased ball detent 7. To establish the first ratio for the car to move off, the manual selector lever or pushbuttons are operated to move the slider 10 to the right, which, since the associated ratio establishing servomotor A is held by its detent 7, causes the lever 12 mounted thereon to turn rightwards and slide the control valve 8 rightwards from the position shown. A pump J then draws liquid from a sump K and passes it through a pipe 35 to a slot v in the slide valve 8, which is now so conditioned that the liquid passes therethrough to a pipe 36 leading to a servomotor D, which disengages the main clutch E. At the same time liquid under pressure passes through the pipe 36 to a servomotor H which acts through links 32 and lost motion pin-and-slot mechanism 31 to shut down the supply of fuel to the motor-car engine, if the accelerator pedal 27 has been depressed to increase the supply of fuel. When clutch disengagement has been completed, the liquid passes through the servomotor D to a pipe 37 connected to slide valves 3, 3<SP>1</SP>, 3<SP>z</SP> on the operated rods of the ratio establishing servomotors. With the three servomotors A, A<SP>1</SP>, Az in their neutral positions, as shown, ports d<SP>1</SP> in the valves 3 are positioned so that liquid under pressure passes through to two pipes 38, 381 leading to the two slide valves 8<SP>1</SP>, 8, respectively. The slide valve 8<SP>1</SP> is still in the neutral position shown, so that liquid under pressure passing through the pipe 38 is prevented from flowing beyond a slot p therein. However, the slide valve 8 has, as described, been displaced to the right, so that a slot p therein passes the liquid under pressure supplied through the pipe 381 to a pipe 40 leading to the first ratio establishing servomotor A. The piston 2 of the first ratio establishing servomotor accordingly moves to the right and establishes the first ratio. When the ratio establishing movement of the piston 2 of the servomotor A has been completed, the slide valve 3 on the operating rod thereof shuts off the supply of liquid under pressure from the pipe 37 to the pipe 38, and instead connects the pump J directly through a pipe 44 to a slide valve F controlled by the accelerator pedal 27 and closed unless the pedal has been fully depressed. Also, movement of the operating rod of the servomotor A has turned the lever 12 on its slide 10 and restored it to its neutral position, so that the slots d, p in the valve 8 are again in the position shown. The pressure of the liquid supplied from the pump J to the pipe 36 now passes through a port d in the control slide valve B<SP>1</SP> to a port d in the control slide valve B and thence through a port d in the reverse control slide valve B<SP>z</SP>. which leads through a pipe 42 to the slide valve F controlled by the accelerator pedal 27. As long as the accelerator pedal is released, the slide valve F is closed and accordingly pressure is maintained in the pipes 42, 36 to maintain both the main clutch disengaging servomotor D and the fuel supply closing servomotor H energized. On fully depressing the accelerator pedal 27, the pin-and-slot connection 31 &c. opens the valve F, which accordingly discharges the pressure of the liquid in the pipes 36, 42 &c. through a pipe 43 back to the sump K. Accordingly the fuel supply servomotor H is de-energized, and the fuel supply to the engine is increased. Simultaneously the main clutch servomotor D is deenergized to re-engage the main clutch E. As long as first gear is engaged, the servomotor D can be re-energized to disengage the main clutch merely by releasing the accelerator pedal and the slide valve F. To establish the second ratio, the control slide 10 is moved leftwards to its second ratio position, thus sliding the valve 8 leftwards, so that the slot p therein connects the inlet pipe 381 to a pipe 39 leading to the opposite side of the piston 2 of the ratio establishing servomotor A. Simultaneously, a slot o<SP>1</SP> in the valve slide 8 connects the pipe 40 to an exhaust pipe 41 through which liquid on the opposite side of the piston 2 is returned to the sump K. The sequence of events is as before, with the ratio establishing servomotor A first disengaging the first ratio and then establishing the second ratio, with consequential disengagement of the main clutch E and closure of the fuel supply by means of the servomotor H. To establish the third ratio after the second ratio has been established, the control slide 10 is moved to its neutral position by the ratio shift lever or press button control, and the control slide 10<SP>1</SP> is moved rightwards to its third ratio established position. The servomotor A first disengages the established second ratio, the port d<SP>1</SP> therein being closed to prevent liquid under pressure passing from the pipe 37 to the pipe 38 until neutral has been established and thus providing a fluid interlock. Accordingly, third ratio cannot be established until the second ratio has been disestablished. Establishment of the third ratio by means of the servomotor A<SP>1</SP>  then takes place in the same manner as establishment of the first ratio already described. Establishment of reverse is effected by the servomotor A<SP>z</SP>, having two positions, and controlled by a slider 10<SP>z</SP> and a slide valve 8<SP>z</SP>. The mechanism may control gearing having more than four forward ratios, Fig. 3 (not shown), in which case the valves 3 have two or more fluid interlock ports d'. In a modification, the main clutch E, Fig. 2, is disengaged by a diaphragm-type vacuum servomotor D<SP>1</SP> according to the position of a valve 19 which, when liquid under pressure is supplied through the pipe 36 to a piston 20, is opened to connect the servomotor to a vacuum tank 22 energized through a one-way valve 24 from the inlet manifold 23 of the car engine. On release of the liquid pressure in the pipe 36, the valve 19 closes and admits atmospheric pressure which re-engages the clutch E. A slide valve 18 on the connecting rod of the servomotor D<SP>1 </SP>is opened when the clutch is disengaged to admit liquid under pressure from the pump J and the pipe 36 to the pipe 37 leading to the ratio establishing servomotors A &c.