Patent GB-1183020-A (GB)
Title: A Semi-Automatic Transmission Mechanism
IPC: F16H63/46
Filed: 1968-11-29
Abstract: 1,183,020. Variable-ratio gearing. FORD MOTOR CO. Ltd. 29 Nov., 1968 [12 Dec., 1967], No. 56668/68. Headings F2C and F2D. In a transmission comprising a hydrokinetic torque converter 32 followed by a synchromesh change-speed gear, the turbine 56 of the converter is connected to the input shaft 68 of the gear by an overrunning clutch 62 and by a releasable coil spring clutch 76 in parallel, the coil spring clutch being automatically disengaged upon ratio shift in the change-speed gear and being prevented from re-engaging on the completion of the shift until the engine torque is sufficient to cause the turbine to speed up. The clutch 76 comprises a coil spring, secured at one end to an inner race 74 splined to the input shaft 68, and expandable into engagement with an outer race 70 fast with the turbine by a control ring 78 which is shifted radially to bring the adjacent end turn of the spring into contact with the outer race to initiate self-energization of the clutch. The control ring 78 is displaced radially by a control lever 96 disposed in a bore 98 of the input shaft 68 and rockable about its mid point 100. The lever acts on the ring 78 by way of a radial plunger 94 and is biased to its operative position by a spring detent 108. The lever 96 is rocked by a plunger 102 which is shiftable radially inwardly as the shaft 68 rotates by engagement with a cam plate 104. The cam plate 104 is adjusted by a shift rail 142 of the change-speed gear which has recesses 168, 170 registering with the plate 104 when the shift rail is in its ratio establishing positions. During ratio shift the cam plate 104 rides out of the recesses and rocks the control lever 96 to disengage the coil spring clutch 76. On the completion of shift the cam plate 104 is withdrawn, but clutch engagement is inhibited until the turbine 56 begins to drive the shaft 68. This is achieved by providing a lost-motion spline connection 66 between the inner race 64 of the one-way clutch 62 and the shaft 68. Driving torque from the turbine shifts the inner race 64 relative to the shaft 68 against the bias of a spring 86 to a position in which a groove 82 in the race 64 registers with a projection 80 on the control ring 78 so that the ring can be shifted radially. In the absence of driving torque the groove 82 and projection 80 are misaligned and the ring is maintained in a concentric position. The gear is of the two-speed constant-mesh type, the shift rail 142 controlling a synchronized double dog clutch sleeve 132 splined to an output shaft 28 and engageable with clutch teeth 138 on a driving gear-wheel 118 for direct drive, and engageable with teeth 128 on a gearwheel 126 to give reduced drive by way of countershaft gears 120, 124. To counteract drag torque when shifting from neutral with the vehicle stationary, a brake 152 can be applied to station the countershaft to facilitate engaging direct drive, and the gear 124 has a spline connection with the countershaft permitting slight angular displacement to facilitate engagement of the low ratio drive. The clutch sleeve 132 is formed with gear teeth 140 engageable with a reverse drive pinion in the neutral position of the sleeve.