Patent GB-637740-A (GB)
Title: Power transmission mechanism for motor vehicles and controls therefor
IPC: F16H61/02
Filed: 1947-07-25
Abstract: 637,740. Hydraulic transmission of power. GENERAL MOTORS CORPORATION. July 25, 1947, No. 19993. Convention date, Oct. 4, 1940. [Class 69 (ii)1 [Also in Group XXIV] In a variable-ratio gear on a vehicle, wherein one clutch C establishes drive from an input shaft 1 to a bevelgeared output shaft 60 through a three-element hydrokinetic torque-converter T, and another clutch D establishes a direct mechanical drive byepassing the torqueconverter (e.g. of the Lysholm-Smith type) both the clutches, the converter and the direct-drive being coaxial, the two clutches C, D, are actuated either (a) Figs. 2 and 4, simultaneously by separate fluid-pressure servos 125, 130 controlled by a common operatoractuated valve, Fig. 5a; or (b) Figs. 6 and 8, by a single common servo 130a, also controlled by a single operatoractuated valve, Fig. 5a. The supply of fluid-pressure to the pipe 122, Figs. 2 and 4, or 122a, Figs. 6 and 8, disengages the fluid-path clutch C whilst simultaneously engaging the mechanicalpath clutch D, the reverse operation, for downshift, taking place by springs when the pressure is released. In Figs. 2 and 4 the clutches C, D, are mounted at opposite ends of the gear, that C, in the fluid-path, being a friction disc-clutch, whilst that, D, in the mechanical path, is a balked synchronized claw-clutch. In Figs. 6 and 8, both clutches C, D are friction discclutches nested at the front of the gear. In Figs. 2 and 4 the input shaft 1 is integral with an inner shaft 2, which, through the disc clutch C, drives the impeller 40 of the torqueconverter, to the runner 30 of which are fast the inner cam-member 18 of a direct-drive one-way roller clutch F and a driving pinion 16 of a reverse-gear, both controlled by a sliding clawclutch 25 splined on an enlargement of a concentric driven sleeve 9, bevel-geared to the final output shaft 60. In the position shown, the claw-clutch 25 connects the outer driveri member of the roller-clutch F to the driven sleeve 9, whilst, moved to the left, it frees the roller-clutch F, and external teeth on it mesh a wheel 28 on a countershaft driven through an idler 32 by the pinion 16, for reverse. An intermediate position provides neutral. The whole gear and an associated power-plant are mounted at the rear of a vehicle and the clawclutch 25 is operated through simple linkage (Fig. 5, not shown) by a dashboard-mounted lever. Synchronized claw-clutch. The mechanical drive claw-clutch D, which directly connects the driving shaft 1 and driven sleeve 9, comprises an axially slidable member 4, Fig. 4, splined to the driving shaft 2 and having peripheral clutchteeth 13, engageable with teeth 11 in a bevelwheel 10 fast on the driven sleeve 9, asynchronous engagement being prevented by a spring-loaded balk-ring 53, which has a permanent friction drag on a, member 56 splined to the driven member 10, and is also connected to the driving clutch-member 4 by teeth 54 which permit circumferential play to provide the usual balking action between the balk-ring 53 and additional axially-spaced teeth 55 on the member 4. The clutch D is engaged, to provide direct mechanical drive by a compression spring 74, Fig. 2, when the latter is released by applying air-pressure through the supply-pipe 122 to a spring-returned single-acting piston in a cylinder 130. The same pressure-supply 122 acts simultaneously in a similar cylinder 125 to release the fluid-drive friction-clutch C, which is of the type engaged by a disc-spring 42 on release of the air-pressure. In Figs. 6 and 8 the friction clutch C is arranged at the front of the gear and'drives the torque-converter through the inner shaft 2 which is now separate from the input shaft 1. The claw-clutch D is replaced by a similar friction disc-clutch D<SP>1</SP>, the clutches C, D<SP>1</SP>, being engaged alternately by a common disc-spring 170, which is biassed by an axially slidable thrust-collar 172, about a fulcrum 162a, 177, to the left to engage clutch D<SP>1</SP> and right for C. The thrust-collar is operated through a crank 173 by a single-acting spring-loaded piston 148a in a cylinder 130a, to which air-pressure is supplied through a pipe 122a, to engage the mechanical-drive clutch D<SP>1</SP> and disengage C. The cylinder 130a also has a central outlet 134b, Fig, 8, controlled by a valve 210 linked to the operating lever 110<SP>1</SP> of the forward-neutralreverse claw-clutch 25, so as to vent the outlet 134b in the neutral position of the lever 110<SP>1</SP>, thus maintaining the piston 148a in its central position with both clutches C, D<SP>1</SP> disengaged to avoid idle-drag whilst shifting the forwardreverse clutch 25. In both constructions air-pressure is supplied to the pipe 122, Fig. 2, or 122a, Figs. 6 and 8, from a pump-filled reservoir under control of the valve, Fig. 5a, operated by a pedal 135 secured to a cam 137, having two setting notches co-operating with a roller 127 on a spring- loaded movable seat 128. In the position II shown, the cam-notch 138 engages the roller 127 and the seat 128 is spaced from a spring-loaded dumb-bell valve 142, permitting the latter to close the clutch-supply line 122 from the pressure-source 120 and vent it at 134a, for torque-converter drive. Moved to position I, the second notch 139 engages the roller, depressing the seat 128 and with it the dumb-bell valve 142, the lower end of which opens the clutch-supply line 122 to the pressure-source 120, whilst its upper end cuts off the vent connection 134a, for direct mechanical drive. In addition to these two normal operating positions, the pedal can be momentarily flicked to a third position III, in which it again pressurises the clutch-supply line 122 which has the effect of temporarily releasing the fluid-drive clutch C without engaging the mechanical-drive clutch D, thus avoiding idledrag and facilitating forward-reverse shift in the Fig. 2 construction. No notch is provided for this position, the pedal springing back to position II as soon as released. Specification 532,496, [Croup XXIV], is referred to.