Patent GB-598153-A (GB)
Title: An improved control arrangement for toothed-wheel change-speed gear
IPC: F15B13/07
Filed: 1945-08-31
Abstract: 598,153. Controlling change-speed gearing. SOC. ANON. A. SAURER. Aug. 31, 1945, No. 22492. Convention date, Sept. 1, 1944. [Class 80(ii)] In a control arrangement for toothedwheel change-speed gearing, applicable to power vehicles, in which the feed of a pressure medium for at least one gear-controlling clutch piston is released on disengaging the main clutch, the piston cylinder has an opening uncovered at the completion of the full gear changing stroke through which overflowing pressure medium passes to operate a member which neutralises a locking device tending to maintain the main clutch in its disengaged position. As shown, several separate gear - controlling clutch pistons are simultaneously operated, of which one only acts directly through an overflow pipe on the locking device, the others acting through similar overflow pipes at the completion of their gear changing strokes to open cut-out valves in the first overflow pipe. Two arrangements are shown having manual and power relay main clutch operation respectively, the changes being preselected in each case. In the first, the manual main clutch pedal 19, Fig. 1, on disengagement, operates through a lost-motion link 15 a rotary valve 10 to connect a normally vented pipe 11 to a compressed air source 1. The air passes through a pipe 13, a space 36 and a pipe 43 to a distributing valve 44, preselectively operated by rotating a speed control 52 co-acting longitudinally with a fixed quadrant 55, and thence by way of certain of pipes 45-50 to the appropriate side of the gear controlling pistons 60-62 to execute the change. During the shift, the main clutch is held disengaged by a locking rod 33 which is forced upwards against spring-pressure, to engage a notch 21 on a quadrant 20 secured to the pedal 19, by the pressure air acting through a pipe 12 on the partial surface of a double-ended stepped piston 27. The piston 62, on the completion of its stroke in either direction, or immediately if it is already in the correct position for the speed required, allows pressure air to enter the overflow pipe 78, which is put into working connection with a pipe 30, communicating with the full surface of the piston 27 to release the locking rod 33, only when intermediate pipes 79, 80, normally vented as shown through pipes 87, 88 and the waisted pistons 83, 84 of cut-out valves 81, 82, are connected to each other and the pipe 78 by the raising of the pistons 83, 84 against spring action when overflow pipes 94, 93 are uncovered on the completion of the strokes of the pistons 60, 61. The speed control lever 52 is held locked in the quadrant 55 during changes by the action of the air in the space 36 below a locking piston 37 acting through a lever 58, but on completion of the change the air passes also via a pipe 42 to the space 40 above the piston, which floats, leaving the lever 52 held down only by a spring 54. A strongly spring-loaded valve 38 vents the space 36 only when mechanically depressed by the piston 37 on raising the lever 52 manually to an abnormally high position when the main clutch remains independently disengaged after a change and it is desired to make another change without passing through intermediate notches in the quadrant. In the second arrangement, gear changing is initiated by slight depression and instant release of the main clutch pedal 109, Fig. 2, which is connected to the operating lever 110 of the rotary valve 10 by a floating lever 106 pivoted on a rod 103 connecting a power piston 100 to the main clutch lever 104. As the piston 100 is pressed to the right by a spring 101 which is much stronger than a spring 114 holding the lever 110 to the left, the initial depression of the pedal 109 rocks the lever 110 to the right where it is held by a catch 119. In this position of the valve 10 compressed air from a source 3 flows through a pipe 11 past a check valve 96 to a chamber 98 and moves the piston 100 to the left to disengage the main clutch and to uncover a port 102 through which the air passes down a pipe 13 to operate the gear change as before. After the change is completed, a spring-pressed piston 118 connected to the catch 119 is raised by the overflowing pressure air passing along the pipes 80, 42, causing the catch to release the lever 110 which returns to its initial position, cutting off the air supply and venting the pipe 11 so that the pressure in the chamber 98 is slowly released through a throttle valve 97 and the main clutch engages smoothly. The pressure air controlling organs actuated by the main clutch lever and the speed control lever may be regulated electrically, instead of mechanically. When applied in a motor vehicle, the overflowing pressure air may be made to cause throttle opening during clutch engagement, or may, in the second arrangement, be prevented from acting on the locking device until the driving and driven members of the main clutch are synchronised.