Patent GB-485101-A (GB)
Title: Improvements in and relating to variable speed transmission control mechanisms
IPC: F16H61/30
Filed: 1936-11-13
Abstract: 485,101. Controlling change-speed gearing; valve-closures. BENDIX WESTING- HOUSE AUTOMOTIVE AIR BRAKE CO. Nov. 13, 1936, No. 31049. Addition to 471,999. [Class 80 (ii)] [Also in Group XXIX] In a fluid-pressure control of a motor-vehicle gear-shifter-lever 23, wherein a double-acting motor 17 slides the lever bodily for establishing a gear, and a double-acting cross-shift motor 16 turns the lever about the piston-rod 24 of the first motor for selecting amongst three striker-rods 18, 19 and 20, the cross-shift motor mechanically operates a three-valve unit 50, directly controlling the supply of fluidpressure to the gear-establishing motor 17. During a shift from neutral to either outer striker-rod 18 or 20, this valve-unit acts somewhat as a fluid-interlock, ensuring that the cross-shift shall have taken place before the gear-establishing motor 17 is energized to introduce the selected speed. During a shift, the main-clutch is automatically disengaged, also by fluid pressure, and is temporarily re-engaged as the transmission passes through neutral. A fluid and spring cushion are provided to retard the latter part of the gear-establishing movement. In order to prevent friction between the lower end of the shifter-lever 23 and the striker-rods due to lateral thrust on the lever, its upper end may be guided in a slotted plate 230, Figs. 12 and 14. Pressure-air from a main reservoir 94 is controlled by a remotelypositioned distributing-valve unit 13, comprising a manual lever 41, guided in a slotted plate 42, and having a cam at its lower end for operating a group of valves 37 .. 40, as described in Specification 471,999. The cross-shift motor 16 is permanently biassed by a double-acting spring 33, Fig. 2, to a central position for selecting the striker-rod 19, which is moved in opposite directions, i.e. to the right and left of Fig. 1, from neutral, for selecting second and third speeds respectively. The other strikerrods 18, 20 select first speed and reverse respectively, by movement in one direction, i.e. to the left of Fig. 1. Second-speed is thus the one one requiring a rightward movement of the shifter-lever 23, and for this purpose the left-hand side of the gear-establishing motor 17 is directly energized by the manual control valve 40, the other manual control-valves 37, 38, 39 being then vented. For all other gearestablishing movements the right-hand side of the motor 17 is energized by one of the valves 37, 38, 39, communicating therewith through the fluid-interlock unit 50, above referred to. This fluid-interlock comprises three spring-loaded ball valves 47, 48, 49, Fig. 2, opened directly, as shown, or through further intermediate balls and push-rods, by a head 51, carried rigidly, or with lost-motion, on the piston-rod 31 of the cross-shift motor 16. The head 51 slides in a chamber 50, communicating through a pipe 52 with the right-hand side of the gear-establishing motor 17. The middle valve 48 communicates through a pipe 55 with the valve 38 of the distributing unit 13, so that when the valve 38 is opened for selecting third-speed, the right-hand side of the gearestablishing motor 17 will be energized, only after the centralizing of the piston-rod 31 by the spring 33 has opened the valve 48. The other two valves 47, 49 communicate through pipes 45, 46 with opposite sides of the piston 31 of the cross-shift motor 16, whereby the chamber 50 and hence the right-hand side of the gear-establishing motor 17 are put under pressure through the cross-shift motor, from a valve 37 or 39 of the distributing-unit 13, only after the valve 47 or 49 has been opened by completion of the cross-shift movement. Two methods of cushioning the latter part of the gear-establishing movement are described. In the first of these, movement, in either direction, of the piston-rod 24, Fig. 4, of the gear-establishing motor is opposed after the piston has travelled far enough to uncover a port 69 or 70, communicating the pressure side of the piston 25 with one or other side of a smaller piston 63, secured to the piston-rod 24 and acting in opposition to the main piston. When the gear-establishing motor is exhausted, the cushioning piston 63 exhausts through oneway valves 76 communicating to corresponding sides of the main-piston. Springs 67 supply a permanent bias to neutral. In Fig. 12, cushioning is effected by a double-acting spring 172, held compressed between cups 173, 174 loosely mounted for limited outward movement on the piston on extension of the rod 123 of the gearestablishing piston 125. After a predetermined travel in either direction of the piston-rod 124, one or other of the cups 173, 174 is stopped by an abutment 180 or 182, and the spring 172 is thereafter compressed to cushion further movement. Neutralizing is effected partly by the spring, and is completed by fluid-pressure, which acts constantly through an inlet 183, on a pair of loosely-mounted pistons 178, 179, acting against shoulders on the piston-rod. The main-piston 125 is formed with lubricantspace 164, communicating with an oil reservoir 165. The means shown in Fig. 1 for providing co-ordinated operation of the main clutch during a change, comprises a clutch-operating element 14, controlled by a diaphragm 83, which is energized by the lifting of a spring- loaded two-way valve 86, such lifting being produced by the gear-establishing piston-rod 24 every time it moves from a gear-engaged or neutral position. The rod has three camnotches 93, which allow the valve to fall, thereby venting the diaphragm and causing clutch re-engagement in these positions. Thus, during a change, the clutch is temporarily re-engaged in passing through neutral. In order to provide sufficient time for the clutch to disengage before the change, the shifter-lever is mounted with lost-motion between collars 27 on the piston-rod, so that the clutch-valve 86 is operated before the lever. Springs 26 may be provided to centralize the lever between the collars. Manual clutch control is provided by a pedal 97, operating a valve 96, controlling a second diaphragm 100, arranged behind the diaphragm 83. Fig. 12 shows a modified clutch-valve 197 for controlling a piston motor operating the clutch. This valve comprises a double-spherical member 189, the upper end of which forms a closure-member between a pressure-inlet 192 and a chamber 200, leading to the clutch-cylinder. The lower end of the member 189 co-operates with a movable seat-member 196, which, when lifted, first cuts off communication through the hollow seat-member 196, between the outlet chamber 200 and an exhaust chamber 193, and thereafter lifts the double-spherical member 189 to open the pressure-chamber 192 to the outlet-chamber 200 and energize the clutch cylinder. As before, the piston-rod 124 has three cam-notches 204, 205, 206, which allow the valve-parts to fall and vent the clutch motor. The exhaust-pipe 194 from the chamber 193 leads to a three-way manual control-valve, which normally vents the chamber to atmosphere, but is connected on one side to a pressure-inlet, so that the controlvalve can be manually operated to change the exhaust-pipe 194 to a pressure-pipe and energize the clutch-cylinder at any time desired. Specifications 476,820 and 485,145 are referred to.