Patent GB-494699-A (GB)
Title: Improvements in gear shifting mechanism for motor vehicles
IPC: F16H61/02
Filed: 1937-04-30
Abstract: 494,699. Controlling change speed gearing. POLLAK, J. E. (Automatic Shifters, Inc.) April 30, 1937, No. 12406. [Class 80 (ii)] A gear-shifting mechanism for motor vehicles comprises a gear-shifting double-acting piston servomotor 61, Fig. 2, operated by differential pressure under the control of a plurality of sets of control valves 207, 142, 71 which can be selectively actuated from a gate lever 175. When the main clutch 19, Fig. 1, is engaged for and during driving, the selector means of the control valves is maintained inoperative while the gear-shifting motor 61 is maintained connected to the source of pressure-differential, e.g. engine-suction 11, with its piston 63 " vacuum-suspended." Gear shifting is prevented without mechanical interlocking, except during clutch disengagement. Shifter rods 27, 28. Fig. 2, of a gear-set 24 are operated alternatively in opposite directions as a truncated ball shifting-lever 31 is swung in two directions through the agency of a cross-shaft 46 by the shift motor 61 and by a cross-shift motor 54. A socket 32 is for a hand lever if the power fails. The main clutch 19, Fig. 1, may be operated by a pedal 22 alone or, as shown, by a suction servomotor 33 controlled by valve mechanism 40 operated from an accelerator rod 17 along with the throttle 14, as described in Specification 449,545. There is a suction pipe 45 from the manifold 11 to the clutch servo 33 and another suction pipe 89 leading to the main speed changing valve chest 71 and having a branch 196 to a clutch-controlled valve cylinder 187. The diaphragm crossshift motor 54, Fig. 13, is connected by a swivel 52 to the cranked sliding cross-shift shaft 46 to move the same endwise, and is worked through two pipes 58, 59, leading through ports 127, 128, Fig. 11, to upper and lower parts of a middle barrel 75 of the main chest 71, Fig. 9. The cross-shift control passes on through a pipe 116 to the chest 207, Fig. 2, and to the middle barrel 161, Fig. 3 of that chest so that the cross-shift is effected by moving the hand lever 175 in the cross slot 174, Fig. 5, in a gate 170. The end barrels 73, 74, Fig. 9, of the main chest 71 are connected through respective ports 125 and 126 to pipes 130 and 131, Fig. 2, to the two ends of the shift cylinder 61 which swings on a pivot 70, Fig. 1. There is a cross suction-passage 87, Fig. 9, connected to suction at 89, and a cross atmosphere-passage 76 connected to the air through a filter 77. Outer slide valves 78, 79 with two valve heads 81, 82 each and a middle slide valve 80 with three valve heads 90, 91, 92 are all operated by diaphragms 109, 110, 111 in three pockets 106, 107, 108 above the three barrels 73, 74, 75. Pipes 114, 115 which control the selector valves of the suction at the two ends of the shift motor 61 pass to a valve chest 142, Fig. 6, in line with the shifter rods 27, 28, Fig. 2, and are continued by pipes 153, 154 to the chest 207 and to outer barrels 208, 209, Fig. 3, of that chest. There is a spring-pressed valve head 158 with a straight edge 162, Fig. 4, splined on a stem 159, Fig. 3, to which the hand lever 175 is secured so that when the lever 175 is rocked left of Fig. 4, the barrel 209 is vented, and when rocked right, the barrel 208 is vented. The lever 175 can be spring-held in the position shown, Fig. 5, in a gate notch 179 and then both barrels 208, 209 can sustain suction, and so can the cross-shift barrel 161, Fig. 3, because a cross port 166 in the hollow stem 159 is out of register with a vent 167. Then, if the clutch be disengaged, the gear will be in neutral with the shift-piston 63 in midposition with full air pressure on both sides of it. The clutch comes in because when the clutch pedal 22 is depressed to the chain line position of Fig. 12 to disengage the clutch, the suction in the branch 196 is passed on through a pipe 186 and through constricted branches 180, 181, Fig. 10, to the two pockets 106, 107, Fig. 9. The end valves 78, 79 are thus raised against their springs so that the ports 125, 126 are both exposed to. the air cross-passage 76, and air at full pressure passes to both sides of the shift-piston 63, Fig. 2. If, however, the clutch is engaged, the valve 193, Fig. 12, closes the suction pipe 196, as shown, and the pipe 186 is vented at 195. The outer pockets 106, 107 are thus both vented and the outer valves 78, 79 move down so that the ports 125, 126 are exposed to the cross suction-passage 87 and therefore the pipes 130, 131 pass suction on to both sides of the piston 63 which is thus vacuum-suspended, and this is the case no matter the position of the manual lever 175, which can be moved about in the gate 170 without any effect. To make changes, the clutch must be disengaged, an operation which connects the pipes 186, 196, Fig. 12, and therefore connects both pockets 106, 107, Fig. 10, to vacuum so that the valves 78, 79, Fig. 9, are both raised and the air cross-passage 76 communicates with both ends of the shift motor 61. If the operator then moves the lever 175 to position II in the gate, Fig. 5, then the barrel 208, Fig. 4, is uncovered and air enters and passes to the pocket 106, Fig. 9, depressing the valve 78 so as to uncover the port 125 to the vacuum cross-passage 87 whereby vacuum is admitted below the piston 63, Fig. 2, and the shift bar 28 moves rearwardly to bring in second speed. The lever 31 engages a hole 139, Fig. 6, in a slide 138, and this stroke of the shift-piston causes a slide valve 147 to move left of Fig. 6 in the valve-chest 142 so as to uncover a vent 146 and connect the passage 144 to atmosphere whereby the pipe 115 is vented and the suction in the pocket 107, Fig. 9, destroyed. The corresponding, that is the remaining, side valve-head 81 then moves down until the port 126 uncovers to the suction cross-passage 87 and suction is admitted to the upper side of the piston 63 while the suction already there is maintained on the lower side. The piston 63 is thus vacuum-suspended in the new or gear position, which facilitates the next operation of the piston 63. The operator may then depress the accelerator to speed up the engine and let in the clutch. Clutch engagement opens both pockets 106, 107 to air with the result that movements of the control lever 175 cannot have any effect on the pressures there and cannot effect any change, while the shift-piston remains vacuum suspended. If the accelerator be released, or the clutch pedal depressed, vacuum is admitted to the end pockets 106, 107 so that the selector valves are brought under control of the gate lever 175. Movement of this lever along slot 173, Fig. 5, to position III closes the barrel 208, Fig. 4, and opens the barrel 209. The shift-piston 63, Fig. 2, moves from one end of the cylinder to the other carrying with it the shift lever 31 and slide 138 so that the port 146, Fig. 6, closes and a port 145 opens so that the piston 63 is vacuum suspended in the high speed position. All this time, a diaphragm 55, Fig. 13, of the cross - shift motor 54 has been held at left by suction in the pipe 59, and that is because the port 128, Fig. 11, has been kept in connection with the suction cross-passage 89, Fig. 9, again because suction in the middle pocket 108 has raised the valve 80 so that an L-shaped duct 96 connects the port 128 to the suction-passage 87. The suction in the pocket 108 is derived from a fine passage 94 axially through the valve 80 connecting through the duct 96 to the suction cross passage 87. To actuate the cross-shift motor 54 therefore, the vacuum in the pocket 108 must be destroyed to depress the control valve 80, and this is done by shifting the hand lever 175 through the cross slot 174, Fig. 5, so that the port 166, Fig. 3, in the stem 159 registers with the vent 167, Fig. 4, so that the pipe 116, Fig. 3, which leads direct to the pocket 108 is connected to atmosphere. This cross-shift is effected pneumatically by the motor 54 in both directions deliberately, and is not effected more rapidly in one direction by a spring, as in the arrangement described in U.S.A. Specification 2,030,838.