Patent GB-549988-A (GB)
Title: Improvements in or relating to variable torque/speed gears
IPC: F16H47/04
Filed: 1941-03-24
Abstract: 549,988. Hydraulic clutches. HOBBS, H. F. March 24, 1941, Nos. 3952 and 10077. [Class 69 (ii)] [Also in Groups XXIV and XXXI] Power transmission apparatus comprises a distributer adapted to divide power in at least three ratios between two shafts leading into a gear box giving at least two speed ratios, the two shafts being geared to a single output shaft. The functions of the output and input. shafts may be reversed. The distributer may comprise mechanical, hydraulic, electrical, or friction gearing. In one form of distributer an engine drives a casing 1, Fig. 4, having three pairs of clutch rings 2, 3, 6, 7, 10, 11. Co-acting dutch plates 12, 14, 16, are fixed respectively to a bevel gear 50, pinion housing 44, and bevel gear 49 of a differential gearing, the gears 49, 50, being fixed respectively to shafts C, D. The clutches may be engaged in order one at a time by pressure rings to which fluid pressure passes via annular ports 31 in a ring 32, the latter communicating with a pump through a control valve described below. When clutch '2, 12, 3 is engaged the whole of the driving torque passes to shaft D, when clutch 10, 16, 11 is engaged the torque passes wholly to shaft C, and when clutch 10, 16, 11, is engaged the torque is transmitted equally between the shafts C, D. The clutches may be held disengaged by springs or by bob-weights 166. A suitable gear box is shown in Fig. 2 in which the shafts C, D are connected to separate gear trains each connectable with a single output shaft F. Shaft C carries fixed and free gears 60, 62 respectively meshing with free and fixed gears 61, 63 on a countershaft 64. Shaft D has a free gear 66 meshing free gear 67 on a shaft 64 and a fixed gear 70 on shaft 64 meshes with a free gear 69 on the output shaft F. Reverse gears 71, 72 are provided on :a separate shaft. The free gears may be clutched to their respective shafts by synchronizing clutch means. In the form shown the ,gear 62 is arranged between flanges 86, 87, on shaft C, and has a piston 78 with spring pressed ring 80 held in position by ball detent 81. When low pressure fluid enters the space 77 the gear 62 and ring 80 are pressed against the flanges 87, 86, to synchronize the speeds. Ultimately the ball detent 81 is disengaged and clutch teeth 76 on piston 78 engage teeth 75 on flange 86. When the fluid pressure ceases the parts are freed by springs 89, 90. In operation gears 61, 67, 69 are clutched and the distributer clutch 16 engaged. All power passes to the shaft C and the drive to the shaft F is through 60, 61, 70, 69. Shaft D runs idle. In the next speed clutch 16 is disengaged and 14 engaged and the shaft F is driven partly through train C, 60, 61, 70, 69 and partly through D, 66, 67, 70, 69. Next clutch 12 is engaged and 14 disengaged and the drive is then wholly through train D, 66, 67, 70, 69. For the next speed, gear 62 is clutched and 61 declutched and the clutches 12, 14, 16 are engaged, in the reverse order. Finally gear 66 is clutched and 69 declutched and a direct drive is obtained from D to F. Each gear clutch is actuated when the respective gear is free from load and the driving torque is not interrupted when changing gear. A more complex form of differential distributer embodies five clutches. Single control means for all of the clutches may comprise a control arm 388, Fig. 14, geared to rotary valves 382, 383, supplied with pressure fluid from pumps 371, 372, on shaft 370 driven from the engine. Valve 382 controls the gear box clutches of Fig. 2 and valve 383 the distributer clutches of Fig. 4, a series of outlet ducts A, F, leading to the clutches. The parts are arranged so that the clutches are actuated in the proper order. A valve 377 controlled by centrifugal means 373 on shaft 370 prevents actuation of the clutches at low engine speeds, and a toothed piston 391 engaging the control arm 388 prevents of too rapid actuation of the latter. The control may be combined with the means described in Specification 545,325, [Group XXIV]. The distributer may be of the infinitely variable type. A hydraulic form is shown in Figs. 7 and 8. Rotors 214, 218, on spindles carried in a housing 220 are slotted to actuate vanes in the form of rollers 215, 219, or pistons, engageable with the walls 246 of cylindrical chambers in a drum 216. Both housing 220 and drum 216 revolve with a central shaft. Housing 220 and drum 216 may be adjusted angularly relatively to one another to a small degree by axial movement of a collar 240 having balls 233 engaging on parallel grooves in members fixed to the parts 220, 216. The eccentricity of the rotors 214, 218, in the cylindrical chambers may thus be varied one rotor being at maximum eccentricity when the other is at zero eccentricity. The rotor chambers are interconnected and supplied with pressure fluid. The power transmitted through the respective rotor depends on the degree of eccentricity. Pinions 212, 224 may be fixed to the spindles 213, 217 and connected to epicyclic gearing driven from a shaft A, Fig. 12. The latter has a cage K carrying a pair of triple planetary pinions. One planetary pinion gears with loose sleeves C1, C3, and with annulus X meshing with gear 212 and the other with loose sleeves C2, C4, and with a sun Y meshing with gear 224. Each sleeve can be held stationary by a dog E engaged by fluid pressure, a brake F being applied just before engaging the dog. The gears X, Y, can thus each be driven at four different speeds and by varying the hydraulic gear the driven shaft B may have any speed between the speeds of X and Y. A further modification suitable for an aircraft supercharger drive has no gear box clutches the input shafts C, D, Fig. 6, being directly geared to the engine shaft 100. Gearing 101, 109. connects the differential distributer casing with the blower shaft 111. The clutches are actuated by the centrifugal force of the actuating fluid. As applied to endless track vehicles each track may be driven by a separate transmission t, Fig. 13, each comprising the combination of a power distributer and gear box with manual fluid controlling valves u supplied from a pump v. The valves are connected to a dash pot y. The transmissions t are driven from an engine z. In any of the distributers and gear boxes described the clutches may be of the freewheel type. Specification 544,936 also is referred to.