Patent GB-494756-A (GB)
Title: Improvements in gear shifting mechanisms for motor vehicles
IPC: F16H61/30
Filed: 1937-02-22
Abstract: 494,756. Controlling change speed gearing. AUTOMATIC SHIFTERS, Inc. Feb. 22, 1937, No. 5268. Convention date, Feb. 20, 1936. [Class 80 (ii)] In fluid-pressure mechanism for shifting gear selector-forks 25, 26, comprising a doubleacting gear-establishing motor 61 and a crossshift motor 71, both energized under control of a valve-unit 217, operated by a hand-lever 235 guided in an H-gate, the cross-shift motor mechanically operates an auxiliary valve 93, in advance of the transmission of the crossshift movement, said valve 93 assisting in the control of the gear establishing motor 61, and acting somewhat as a " fluid-interlock " to render possible preselected changes between the gears lying in the same longitudinal direction but on opposite sides of the gate (viz. first and high speeds, and second and reverse speeds). The device is described as an improvement on the gear-shifting system set forth in U.S.A. Specification 2,030,838, which has a rapid action by virtue of " vacuumsuspension " of the gear-establishing piston, described below. Power for a preselected shift is rendered operative by a valve 187, operated by the main clutch-pedal 22, which latter is operated by a vacuum motor 33, energized by suction in an engine inlet-manifold 11, under control of a valve-unit 40 opened by release of the accelerator pedal, as described for instance in Specification 449,545. The selector-forks 25, 26 are shifted by the lower end of a truncated ball-mounted lever 31, provided with a socket 32 to receive an emergency manual lever for normal gear-shifting, when desired. The shift-lever 31 is power operated through a shaft 46 having a cranked part 48, apertured for passage of the lever 31. The shaft 46 is rocked in either direction to impart gearestablishing movement to the lever 31 by an arm 68, splined on the shaft 46 and pivoted to the piston-rod 64 of the gear-establishing motor 61. Transverse sliding movement of the shaft 46, for cross-shift of the lever 31 is effected through a bell-crank 78, connected to the crossshift motor 71 and to the interlock-valve 93 in a special manner described below. The crossshift motor 71 is a single-acting diaphragm, permanently biassed by a spring 76, Fig. 10, in the direction for selecting second- and highspeeds, and mounted on the gear-establishing motor 61 so as to form a unit therewith. Such unit is pivotally mounted at a fixed point 70, and is controlled through a triple relay valveunit 98 comprising a central valve 108, Fig. 6, having an outlet port 121, connected by a pipe 122 to the cross-shift motor, and two outer valves 106, 107 having outlet ports 116, 117 connected respectively through pipes 118, 119 to opposite sides of the gear-establishing motor. The valves 106-108 are constantly biassed by springs 146 into the lower position (shown) in which their outlet ports communicate with a cross-passage 114, permanently connected to engine-suction through a pipe 115, and are selectively raised by suction acting above diaphragms 137 into the upper position in which they vent the gear-shifting motor units to atmosphere through a lower cross-passage 104, having an air-cleaner 105 in its atmospheric outlet. The diaphragms 137 are formed by a single flexible sheet, clamped by the cover which forms the diaphragm-chambers. The diaphragm-chambers 134, 135 of both the outer gear-establishing valves 106, 107 permanently communicate through restricted orifices 183, Fig. 7, and a pipe 186, with the clutch-actuated valve 187, so that whenever the clutch-pedal 22 is depressed, both diaphragm-chambers are placed in slow communication with the suction line 115, and are slowly vented by the clutch-valve 187 when the clutch-pedal is released. The diaphragmchamber 136 of the cross-shift valve 108 permanently communicates with the suctionpassage 114 through a boring 113 restricted at 144, the chamber 136 being instantaneously vented to allow the valve 108 to fall and energize the cross-shift motor 71 when the manual preselector lever 235 is moved into the low- and reverse-channel 239, Fig. 4, of an H-gate 237 guiding it. The energization of the cross-shift motor follows immediately on operation of the selector-valve, being independent of the actuation of the clutch-pedal. The diaphragm-chambers 134, 135 controlling the gear-establishing valves are vented to atmosphere, as described below, during the entire time the clutch-pedal is released, irrespective of the position of the selector-valve, so that the valves are always depressed to connect both sides of the gear-establishing piston 63 to suction. Such condition is termed " vacuumsuspension " of the piston. To effect a shift, the atmospheric connections to one of the gearestablishing relay diaphragm-chambers 134, 135, and possibly also of the cross-shift relay chamber 136 are cut off, as described below. Depression of the clutch-pedal 22 then sends suction through the clutch-valve 187 and the restricted passage to the chamber 134 or 135 which has been cut off from atmosphere. The corresponding valve 106 or 107 is thereby actuated to vent the appropriate side of the piston 63 and start the gear-shift movement. The lowermost position of valves 106, 107 is adjustably limited by screws 124 so that the valves partly cover the ports 116, 117 and restrict the communication between the cylinder 61 and suction. This ensures rapid movement to neutral and slower movement to gear positions. In order to ensure that the gearestablishing piston always first moves to neutral even if the selector-valve lever 235 has been preselectively shifted across the gate to a position on the same longitudinal side thereof (i.e. from low to high speed), the atmospheric connections of the relay diaphragmchambers 134, 135 are effected through two parallel paths, one of which comprises a valve 206 having a sliding closure-member 212, Fig. 11, secured to a slotted plate 202 which moves rigidly with the gear-shift lever 31 in its gear-establishing movements. The valveseating 206 has two cross-passages 208, 209 connected by pipes 141, 142, Fig. 2, to the relay diaphragm-chambers 134, 135. In the neutral position, Fig. 11, both passages 208, 209 are covered by the member 212, but in either opposite gear position one of them is vented to atmosphere, whilst the other is cut-off therefrom, and it is this cut-off that ensures an initial movement to neutral in a "throughthe-gate " shift, The other parallel path is to the selector-valve 217 through the same pipes 141, 142, and pipes 96, 97, which are put into communication with pipes 94, 95, leading to the selector-valve, by the " fluid-interlock " valve 93 operated by the cross-shift motor 71 described below. The valve 93 includes a simple piston closure-member 90, Fig. 10, having a pair of annular grooves for connecting the pairs of pipes 94, 96 and 95, 97 in the position shown in Fig. 10, which is that in which the shift-lever is in the second- and high-speed channel, and also connects them when the lever is in the low-and-reverse channel. In such positions the second parallel path is thus completed to the manual selector-valve 217, which is merely a triple vent-valve comprising a disc closure member 224, Figs. 3 and 4, turned by longitudinal movements of the hand-lever 235 to cause apertures 228 or 229 to register with and vent appropriate passages 222, 223 leading to the pipes 94, 95. The pipe 143 of the cross-shift relay diaphragm-chamber is vented through passages 230, 231 in the selector-shaft 225 when the lever 235 is moved across the gate 241 to the left of Fig. 4, against spring-resistance 234. In operation, if a shift is to be made between gear-positions on the same transverse side of the gate, i.e. between low and reverse, or between second- and highspeeds, the cross-shift motor 71 will be unaffected so that the interlock-valve 93 will maintain communication between both relay diaphragm-chambers 134, 135 and the selector valve pipes 94, 95, an appropriate one of which will have been cut-off from atmosphere when the lever 235 has been preselectively moved to its new gear position. When the clutch-pedal is depressed, suction is sent through the clutch-valve 187 and restricted orifice to lift the diaphragm of that particular chamber, thereby venting one side of the gear - establishing piston 63, breaking its " vacuum suspension " and causing it to move to the new gear position. When the new gear is established, the valve 212, Fig. 11, moving with the shift-lever 31, uncovers to atmosphere the passage 208 or 209, leading to the diaphragmchamber 134 or 135 which had previously been cut-off from atmosphere by the manual selectorvalve 217, and simultaneously covering the passage 209 or 208 leading to the chamber which had previously been vented by the selector-valve, although this latter chamber remains vented through the still effective parallel path to the selector-valve. Both chambers 134, 135 are thereby vented and the previously lifted valve 106 or 107 falls so that both sides of the gear-establishing piston are again connected to suction and the piston is " vacuum-suspended" ready for the next shift. For a change involving a cross-shift through the gate, i.e. between low or reverse and second- or high-speeds, the initial movement to neutral is controlled solely by the valve 206, Fig. 11, the parallel path through the selectorvalve 217 being completely out off by the interlock-valve 93 until the cross-shift is complete, whereafter the selector-valve again takes over the control. For this purpose, the diaphragm 74, Fig. 10, of the cross-shift motor is connected to the interlock valve-member 90 through a lost-motion lever 85, pivoted intermediate its ends to a bell-crank 78, through which the motor effects the cross-shift of the cranked shaft 46. As soon as the cross-shift motor is energized for movement in one or the other direction, respectively by its spring 7