Patent GB-706704-A (GB)
Title: Improvements in variable speed power transmission devices
IPC: F16H47/06
Filed: 1951-02-22
Abstract: 706,704. Change-speed and reverse gear; friction and free-wheel clutches. AKTIEBOLAGET LJUNGSTROMS ANGTURBIN. Feb. 22, 1951 [Feb. 23. 1950]. No. 4307/51. Class 80 (2) The same number (two) of ratios forward and reverse is provided oy arranging between an input-driven hydrodynamic torqueconverter 32 and a simple clutch-controlled two-speed gear 154, 158, driving a parallel output shaft 156, a bevel planetary reverse gear, the reverse band-brake 94 and forward solid-drive disc clutch 116 of which are applied, respectively, by pistons 126, 120 actuated by oil pressure under the control of individual valves 128, 122 (the latter rotating with the clutch, the former stationary), connected by linkage 250, Fig. 5, so that only either one can be under engaging pressure at any time. The torqueconverter 32 is of the usual overrun reactor type, and has a direct-drive fluidpressure applied lock-up disc-clutch 38, whilst the two ratios of the mechanical gear are controlled either by two fluid-pressure applied disc-clutches 130, 132, Fig. 1, or by a single similar clutch 130, Fig. 3, for high speed, and a reversible overrun clutch 178 for low. Change-speed and reverse gear arrangement. The reverse gear comprises bevel planets 90, in a carrier band-braked at 94 for reverse, and meshing an input side-wheel 118 fast on a hollow shaft 36 carrying the converter-turbine, and an output side-wheel 100, fast with a common casing 102 of three disc clutches, the first, 116, for clutching together the two side-wheels for forward drive; the second, 130, for driving the final parallel output shaft 156 at low speed through a hollow shaft 146 and wheel pairs 154, 158; the third, 132, providing high speed through a hollow shaft 162 and wheel-pairs 168, 160. A. central shaft 28, splined to the input shaft 22, passes through to the rear of the transmission for driving auxiliaries. In Fig. 3 the low-speed disc clutch is omitted, there being only a single disc clutch 130 (in addition to the forward-drive disc clutch 116) which drives the high-speed train 174, 176. The low-speed wheel 170 is directly driven through the reverse-gear output wheel 100 and clutchcasing 102, and its meshing wheel 182 drives the final output shaft 156 through a reversible oneway roller clutch 178 which overruns when the high-speed clutch 130 is engaged. Free-wheel clutch. This comprises rollers 178 in a cage 180 which is automatically turned into appropriate limit positions for forward and reverse drive by the reverse brake-piston 126 acting through a bellcrank 186 and an axially slidable member 196 having a helix connection with an inner member 199 which is thereby caused to turn the roller-cage 180. Servo fluid system. A pump 70, input-driven through gears 58, 64, 62, supplies pressure-oil through a control-valve (not shown) either to the converter. through passages 74, 76, 80 and simultaneously to the right, release, side of the presser-plate 34 of the lock-up clutch 38, for fluid drive, or alternatively to reduce those parts to a low-pressure (0.4 kgm. per sq. cm.) and to supply pressure through passages 88, 84, 85 to the left of the presser-plate 34 for assisting springs 83 in engaging the lock-up clutch 38 for wholly mechanical drive. An extension of the pump-shaft drives a second pump 72 for supplying servo-pressure to the presser-plates 120, 134, 136 of the forward-drive clutch 116, the ratio clutches 130, 132 and to the piston 126 operating the reverse brake-band 94. The forward clutch 116 and reverse brake 94 are supplied through the interlinked rotating and non-rotating valves 122, 128, above referred to, giving forwardneutral-reverse control. In Figs. 1 and 5 fluid pressure is admitted to the ratio clutches 130, 132 through a three-position selector-valve 142 rotating with the common driving clutch-housing. Overlap shift is provided by a timing valve 144 which only 'exhausts a superseded clutch 130 or 132, at 256 or 254, after engaging pressure has begun to build up on the newly-selected clutch 132 or 130, such pressure acting on opposite, sides of a spacer piston 261 to move spring-loaded valves 260 or 262 outwards to the respective exhaust positions. The valve control of the Fig. 3 form, Fig. 4 (not shown), differs in that the forward- and high-speed clutches 116, 130 are now controlled by a common piston valve rotating with the clutch, and linked through an operating lever to the stationary reverse brake-valve. This lever (as well as all the valves) has a central neutral position with a forward low and high speed on one side and a reverse low and high on the other, all five positions being in line.