Patent GB-811487-A (GB)
Title: Improved variable-speed power transmission mechanism for motor vehicles
IPC: F16H47/06
Filed: 1957-05-27
Abstract: 811,487. Controlling change-speed gearing; clutches. GENERAL MOTORS CORPORATION. May 27, 1957 [June 21, 1956], No. 16720/57. Class 80 (2). Movement of a manual shift lever to select forward, neutral or reverse drive causes positioning of a valve to connect the servo of a fluid-pressure operated clutch to exhaust during that movement, and to a source of pressure on completion of the change. A power input shaft 10 drives an intermediate shaft 50 through a double fluid-pressure operated clutch assembly B and a hydrodynamic torque converter unit A in the manner described in Specification 807,395. From the shaft 50 the drive is transmitted either directly through a gear 86, splined to shaft 50, having dog teeth 87 engaged by clutch sleeve 94 splined to a hub 95 fixed to the output shaft 110, or through gear 86, countershaft idler gears 88, 89, 91 to a gear 93 formed on the sleeve 94, to provide low ratio reverse drive. The sleeve 96 is moved axially by a fork on a lever 96 actuated through linkwork by a hand lever 101 moving in a slot 102 in a housing 103. The slot 102 has three short lateral slots corresponding to forward, neutral, reverse, it being necessary to move the lever laterally out of these slots to permit selection of the desired ratio, this lateral movement closing a switch 104 mounted on the casing 103. Control system (Fig. 8). An engine driven pump 111 supplies pressure fluid to a passage 113 leading to a port 114 in valve body 115 containing a converter clutch control valve 117, controlling the clutch 24 through port 122 and passage 65, and a direct drive control valve 130, controlling the clutch 22 through port 138 and passage 75. The valve 117 is biased by a spring 121 to admit fluid to the clutch 24 and the valve 130 is biased by a spring 134 to exhaust the clutch 22 through the exhaust port 137. A shuttle valve 142 having a reduced stem 146 is biased to mid-position in a housing 143 by springs 157, 158 and has ports 147, 148, 149 connected to a passage 1261, 154 connected to a first solenoid valve 160, 152 connected to a duct 82 leading to the pressure chamber 20 of clutch 22, and a duct 150 leading to exhaust. The first solenoid valve 160 is opened by closure of the switch 104 to admit fluid from the passage 113 to a space 153 above the valve 142. A second solenoid valve 170, opened at a predetermined speed (18 m.p.h.) by governor switch 194 admits fluid pressure to the direct drive control valve 130 at space 140, and a third solenoid valve 180, opened by a manual switch 195 admits pressure fluid to the space 126 above the converter clutch control valve 117. An accelerator " kick-down " switch 191 is provided in the energizing circuit of the solenoid valve 170. Operation.-Starting from rest, the lever 101 is moved into the forward slot to engage the clutch sleeve 94 with dogs 87; since the valve 130 is biased to exhaust and valve 117 is biased to pass fluid to the converter clutch 24 and the three solenoid valves are closed, the drive is transmitted through the torque converter to the output shaft. At a predetermined speed, the switch 194 closes to open solenoid valve 170 and pressure fluid moves the valve 130 against spring 134 to cause fluid to pass from the port 114 to the direct drive clutch 22 through port 138, duct 74 and passage 75. As the clutch 22 engages and pressure is built up in the chamber 20, this pressure is transmitted through passage 85 to the shuttle valve 142, which moves upwards to allow pressure fluid to pass through port 149 to the chamber 128 to move the valve 117 against the spring 121 to exhaust the clutch 24, thus drive is transmitted through the direct drive clutch 22 only. Accelerator " kick-down " opens the switch 191 to cause spring closure of the solenoid valve 170 and the drive reverts to converter drive regardless of the output shaft speed. Closure of manual switch 195 opens the solenoid valve 180 to allow pressure fluid to move the valve 117 downwards, against the pressure in chamber 128, to engage the converter clutch, when the direct drive clutch is engaged, to provide hydrodynamic braking. Movement of the lever 101 out of a lateral slot into the slot 102 closes the switch 104 to energize the solenoid valve 160 and allow pressure fluid to move the shuttle valve 142 downwards to admit fluid to space 128 which moves the valve 117 to disengage the converter clutch 24, thus both clutches 24 and 22 are disengaged during shift movement of the lever 101 to any of the three selective positions.