Patent GB-418663-A (GB)
Title: Improvements relating to power transmitting mechanism
IPC: F16H61/664
Filed: 1933-01-30
Abstract: 418,663. Variable-speed friction gearing; controlling variable-speed gearing. GENERAL MOTORS RESEARCH CORPORATION, Detroit, Michigan, U.S.A. Jan. 30, 1933, No. 2926. Convention date, Feb. 3, 1932. [Class 80 (ii).] Consists in variable-speed gearing having spaced toric races such as 90, 92, Fig. 1, a plurality of intermediate rollers, control means connected to one only of these rollers, such as a roller 94M, Fig. 9, and means responsive to inherent forces set up by the master roller 94M for automatically adjusting the other rollers such as 94. The invention is described applied to twin sets of rollers such as are described in Specification 369,657, all three rollers 95, Fig. 1, of the other set being non-master rollers which follow the setting of the master roller 94M. Two end races 91, 92, are rotationally rigid with an output shaft 35, the middle double race 90 being connected through a drum 100 to an input shaft 32. A smaller compartment 22 of a gear casing H encloses manually selective reversing-gearing, a governor 281 which runs while a vehicle driven by the gearing is in motion and which controls the frictional variable gearing, and a lubricating pump 316, Fig. 5, adapted to start circulation of oil prior to starting the vehicle. The speed of the variable gearing is varied by inclining the master roller 94M, Fig. 9, about a line connecting its points of contact with the races, that is, perpendicular to the plane of Fig. 9. This roller precesses or runs on spiral paths on the races and, as it does so, tilts about a normal axis of tilt tt to a new speed position. The non- master rollers of the two sets do not incline but tilt to follow to the same speed after precession has been initiated by their bodily displacement. The rollers are supported on the arms of two spiders and are adapted to tilt about oblique axes as shown in Fig. 11 so as to terminate the precession in a position of equilibrium as described with reference to Fig. 11 of the Specification referred to. The middle race 90, Fig. 1, is supported centrally on a sleeve 110 supported in turn by a fixed frame member 111. Space is left between the sleeve 110 and the shaft 35 for a load-equalizing sleeve 161 to wabble eccentrically. The sleeve 161 is formed as a rigid floating unit with spider arms 160, 162 supporting the rollers of the rear and forward sets respectively. This floating unit is prevented from turning with respect to the housing by two elastic arched arms 164, Fig. 9, in the plane of the rear set, with ball ends 165 supported in horizontally slidable bearings 166. The elasticity of these arms allows vertical movement of the unit, which can thus float in any direction laterally as well as longitudinally, being centred by springs and dampers such as 185, Fig. 9, and 194, 180, Fig. 1. Speed varying control applied to the master roller 94M inclines that roller to its tracks on the races so that by precessing it tilts about the axis tt. The load upon it alters and its thrust on its spider arm end 200 alters. The spider arm then floats from position n, Fig. 12, to position n<1>. Since the whole spider moves, the arm ends of the following rollers 94 of the same set move from positions n<2>, n<4> to positions n<3>, n<5>, respectively, that is, through half the distance of the arm end at n. The roller axes instead of meeting at a point o on the gear axis, as is required for steady transmission or equilibrium, now meet at a point o<1> not on the gear axis. In consequence. of the oblique mountings 205, Fig. 11, the following rollers 94 of that set go on precessing until they stop in a new speed position with the axes meeting at a different point o, Fig. 12, on and displaced along the gear axis. The load on this set has now altered and the oblique setting at 205, Fig. 11, now causes the floating unit of tube 161 and the two spiders to slide axially. This causes the other set of three rollers 95 to begin precessing, which goes or until these rollers have tilted to the same angle as the rollers 94M, 94, when it terminates in a position of equilibrium. The inclined mountings 205 of the five following rollers 94, 95 are simple plane-sided wedges since these rollers are always carried bodily as between positions n<2>, n<3>, Fig. 12. The mounting of the roller 94M comprises parts shown in Figs. 9 and 10. The obliquity is in a section through two parts of a cylinder 211 which fit over the flat end 200 of the spider arm 160 and are held by a pin 201. This cylinder slides in a journal piece 202M with a land 226 on its end parallel to the line tt. A bridge piece 224 engages over this land and has spring arms 225 which engage over a hard ball 234 which is between a control yoke 218 and a friction pad 228. The pad 228 bears against a side of the roller 94M so that the yoke 218 is carried a limited distance with the roller to the left, as shown in Fig. 2, in forward running, and to the right when the reverse gearing is operative. The upper end of the yoke 218 carries a plate 236 with a hard ball 237 fixed centrally thereto as shown in Fig. 13a. The control is applied by turning a pair of plates 244 which bear on the ball 237 and are carried by a rock shaft 240, Fig. 9, actuated by a lever 243, Fig. 4. In order that the rate of speed change may vary in accordance with the tilt or ratio position of the roller, the axis c, Fig. 13a, of the shaft 240 is offset from the normal axis of tilt tt, Fig. 9. Traction pressure is maintained at the back of the race 92, Fig. 1, by torque-sensitive means which is additional to a main annular spring 141. There is a positive connection 134 between the back of the race 92 and a collar 131 splined at 130 on the shaft 35. Barrel shaped rollers 154 like those described in Specification 221,232, [Class 80 (ii)], are arranged between the inclined flanks of recesses in the back of the race 92 and in the forward face of a hard collar 150 rigid with a universal joint yoke 40 which can turn sufficiently relatively to the shaft 35 to produce the required torque loading. In the arrangement shown, the speed control lever 243, Fig. 4, is connected through a doubleacting spring connection 253 and link 257 to the long arm 260 of a bell-crank lever the twin shorter arms 266, 267, Fig. 2, of which engage a governor-controlled sleeve 270. The bell-crank lever is pivoted on a balancing member 263 which rocks on pivot shaft 264 and is connected by a link 294, Fig. 4, to a byepassed adjustable dashpot 295 submerged in oil. The pivot shaft 264 protrudes above the casing as shown in Fig. 2 and a lever 292 is fixed thereto for independent manual control of the variable gearing. The dashpot 295 checks too rapid movement towards low speed. The sleeve 270 slides on a vertical shaft 271, Fig. 5, which is driven through a worm 290 from the idler 64 of the reverse gear. The sleeve 270 is pressed downwards by cam arms 283 on governor levers 280 in two stages, first against a lighter spring 288 and then against a stronger spring 285. Increased speed of the sleeve 270 through the linkage 257, 240 inclines the master roller 94M for increased speed of the output shaft. The reversing-gearing is operated manually through a rock shaft 76, Fig. 5, and sliding selector shaft 70, Fig. 7, with three positions locked by expanding spring dogs 83. The shaft 70 has a double fork 73 carrying with it as it slides a dog clutch 53, Fig. 1, engageable with a dog clutch 51 on the clutch shaft 30 for forward driving and carrying with it also a gear 63, which is, for reverse driving, engageable with the reversing idler 64 always in mesh with a gear 66 fast on the input shaft 32 of the variable friction gearing. The idler 64 is thus always driven when the vehicle is in motion, and so, therefore, is the governor. The gear 63 slides on a sleeve countershaft 61, Fig. 5, driven constantly through a gear 60, Fig. 1, constantly meshing with a gear 50 fast on the clutch shaft 30. The friction gearing is lubricated in part by splash within the casing 20. Oil passes through a screen 310 to a sump below the casing 20 and is sucked in by a pump 316, Fig. 5, constantly driven through the sleeve countershaft from the clutch shaft 30, so that forced lubrication is effected before the vehicle starts. Oil passes from a pressure chamber 218 with a relief valve 320 along a duct 330, Fig. 1, and up a radial duct 333 to within the floating tube 161, then out radial ducts 337 in the spider arms to the roller mountings. The forward races are sprayed with oil from a jet 340 leading from a support dash-pot 194 of the tube 161. The rear races are sprayed through ducts 341, Fig. 9, in the spring arms 164, and jets 342. The governor is lubricated by oil forced up through a central duct 272, Fig. 5. The Specification as open to inspection under Sect. 91 refers also to British Specification 254,341, [Class 80 (ii)], and to U.S.A. Specification 751,958. This does not appear in the Specification as accepted.