Patent GB-439855-A (GB)
Title: Improvements in or relating to variable speed power transmission apparatus
IPC: F16H61/02
Filed: 1934-06-16
Abstract: 439,855. Variable speed epicyclic gearing. FREEBORN POWER CONVERTERS, Ltd., FREEBORN, J. E., DEGENHARDT, W. R., and FRAINE, A. F. DE, 49, Moorgate, London. June 16, 1934, Nos. 31635/35 and 31646/35. Divided out of 439,828. [Class 80 (ii)] Variable-speed gearing suitable for driving vehicles comprises two or more epicyclic trains such as S, T, Fig. 10, arranged in series with the driven member 164 of one train S driving on to the driving-member 158a of the next train T, each train having one member such as 172 prevented from rotating backwards, and there being automatic means for disabling or driving solid each train in turn under the joint control of speed responsive and torque responsive elements. Thus 158, 160, 162, 164 is a train in which the planet-carrier 172 is kept from rotating backwards by a resilient detent 174, Fig. 11, when the gear train is operative to drive a hollow shaft 166 on reduced speed. A manual clutch 124 connects a driving-shaft 116 to a flange 146 which turns anti-clockwise of Fig. 11 and through collapsed centrifugal levers 152, angle levers 188, a flange 154, and sleeve 156 drives the first gear 158 of the train. Since the carrier 172 cannot yield rearwardly, the gearing operates, yielding reduced speed. The speed effect tending to expand the levers 152 through the lever heels 150 opposes the driving torque on the flange 146. When the speed effect predominates, the flange 146 is thrust back against the drive and the weighted levers 152 expanding thrust the angle levers 188 axially of Fig. 10 so as to engage a plate clutch 180 connecting the sleeve 156 to bolts 186 on the planet-carrier 172. The train is thus clutched solid on high speed, the detent 174 overrunning. Immeddiately the torque effect predominates, change back to reduced speed takes place. The second train 158a, 160a, 162a, 164a is similar, to the first. When both trains are operative this second train T is turning slower than the first and transmitting greater torque owing to the reinforcing effect of the pawl 174 of the first train. Therefore, the first train 5 is disabled by the joint automatic action before the second train T is disabled. They are disabled one after the other in that order, and return to geared drive, first the train T, and then the train S. Driven plates 140 of a main clutch are planetary, being freely supported on spindles 142, like the arrangement of Fig. 2 and as described in Specification 426,407. The detent pawl 174, Fig. 11, is rendered noiseless by one or a pair of flaps 285 which engage lightly against or over the detent disc 172. The overrunning disc lifts and holds the pawl clear. This pawl is cushioned by a curved spring-pressed lever 181 which laps more and more against a pawl-carrying lever 175 as the spring 183 yields. In Fig. 7 (not shown), is illustrated an arrangement which yields three sub ratios, direct drive, and a reverse. In each of three epicyclic trains, an annulus drives, a planet-carrier is driven, and a sun is kept from rotating backwards on geared drives. Each train is disabled or locked solid by a plate clutch put in and out by a combined speed and torque responsive control like that shown in Fig. 11. The main clutch in this arrangement is automatically engaged centrifugally, and has planetary driven plates. In both series arrangements so far described, only a part of the torque is taken by the plate clutch of the gear train, which clutch can therefore be made small. In Figs. 1-6, is illustrated an arrangement with three sub ratios direct drive, and reverse, in which the full torque is taken by the clutch of each gear train, which clutch is therefore relatively large. On all forward speeds, a tail shaft 22 is connected by a dog clutch 30, 32 to the boss 34 of the last train sun 96, which is fast on an intermediate shaft 36. The carriers of the stepped planets of three trains B<1>, C<1>, D<1> are kept from rotating backwards by detent pawls 104, Fig. 3. The pawl shown engages a recess 102 in the carrier 94B of the train B<1>. This pawl is cushioned by a spring 110 which laps more and more as it yields. A clutch D, Fig. 1, picks up the drive automatically on first speed, the three trains being then all operative to reduce. Clutches C, B, A thereafter engage in succession as speed predominates over torque to clutch solid the trains D<1>, C<1>, B<1> in that order, the driven member 68 of the last-engaged direct-driving clutch A being fast on the intermediate shaft 36. Fast to a driving flywheel 38 is a plate 40 loose on the shaft 36 and driving through centrifugal levers 42, Fig. 4, and a lug 46, a second plate 48. The plate 48 drives another plate 48B, which drives a plate 48C, which drives a loose plate 48D. The centrifugal levers 42 act on the loose plate 48D first to draw the plates 48D, 48C together to engage the clutch D and so pick up the drive on first speed. Then the levers 42 act to engage the clutch C which is between the plates 48C and 48B and so on. Fig. 6 shows the balance between the speed and torque in the case of the clutch A, the other clutches being similar. The driving disc 40 carries the centrifugal lever 42 a heel 44 of which lever initially passes on the drive to a lug 46 on the next plate 48. As speed predominates, the plate 48 is thrust round relatively leftwards against the resisting torque, upon which ball-ended toggle links 50 draw the plates 48 and 40 together, thereby engaging the laminated plates of the clutch A. The driving plates 60, Fig. 2, of this clutch are annular around the shaft 36, but the driven plates 62 are in five planetary groups around axles 66 on the driven disc 68. The other clutches B, C, D are similar, driving on to sleeves connecting to the driving suns respectively of the gear trains B<1>, C<1>, D<1>. For reversed drives, the clutch 30 is engaged alternatively with a clutch 100 on an annulus 98 of the train B<1>. The reaction on the carrier 94B of this train reverses, and to take care of this, an oppositely-set detent pawl 116, Fig. 3, is provided. The four sets of levers 42 act the same in reversed drive, since their direction is not reversed, but the speeds are less than the forward ones. The clutch A effects highest reverse by driving the gear 96 direct.