Patent GB-485751-A (GB)
Title: Improvements in or relating to a selective gear transmission for an automotive vehicle
Filed: 1936-08-24
Abstract: 485,751. Gear-selecting mechanism. VACO PRODUCTS, Inc. Aug. 24, 1936, No. 23211. Convention date, Aug. 22, 1935. [Class 80 (ii)] In a selective gear transmission for a vehicle the gear changes are effected by engine suction on actuation of the clutch pedal. The suction is supplied through a conduit 41 connected to the intake manifold of the engine to pistons 25, 26 in cylinders 27,28, actuating selector rods 17, 18 for three forward speeds and a reverse. The suction to the cylinders is controlled by a selector valve 43 controlling the ducts 50, 55, 57 and 60 and a master control valve 65 in the suction line 41 operated by the clutch. The positions of the selector valve for the three forward speeds are indicated by the numerals 1, 2, 3 and the neutral position by the letter N. The valve is normally held in neutral position by a spring 75 acting on a piston 70 of the valve 43, the other end of the valve 90 being held by a stop 97 acting against a bell-crank lever 93 in operative connection with the valve 43. On operation of the clutch pedal 15, the stop 97 is removed by a cable 100 and the valve moves to its first speed position, and on further depression of the clutch pedal the valve 65 is opened to provide the suction for effecting the gear change, the clutch then being re-engaged. As the speed of the vehicle increases, a centrifugal device 115 driven off the vehicle driving shaft 11 actuates a valve 111 which is disposed in a suction line 72 from the engine intake manifold to the piston 70 of the valve 43 which moves the valve to the second speed position against spring 75, where it is retained temporarily by a catch 81 engaging a notch 80 in the valve member. On depression of the clutch again the valve 65 is opened for second speed to be engaged and the catch 81 is released by a cable 82 from the clutch pedal which allows the valve to move into the third speed position ready for the next disengagement of the clutch which will bring third speed into operation. To obtain reverse speed a separate reversing valve 62 is actuated by a control cable 61, the selector valve 43 being in its neutral position. A change from third speed to second may be made at the volition of the driver, even though the valve 43 is in the third speed position, by a full depression of the clutch pedal to operate, through a cable 105, a sliding pin 101 in a slot 103 of the bell-crank lever 93 which moves the valve 43 positively into its second speed position against the suction on the piston 70 and the second speed is thereby engaged. When the vehicle speed falls sufficiently the centrifugally operated valve 111 is operated to relieve the suction on piston 70, which allows the valve 43 to move back into the neutral position and the gears are moved accordingly on the next operation of the clutch pedal. In various modified arrangements the shifting into the intermediate gear is obtained by modifying the suction on the piston 70. This in one case is done by a separate relief valve under the control of the driver whilst in another case it may be effected by sudden opening of the throttle, which results in a falling off of the vacuum on piston 70, which allows the movement of valve 43 into the second speed position.