Patent GB-658964-A (GB)
Title: Improvements in or relating to variable-ratio power transmission apparatus
IPC: F16H3/66
Filed: 1947-12-09
Abstract: 658,964. Change-speed epicyclic gear. RAVIGNEAUX, P. Dec. 9, 1947, No. 32426. [A Specification was laid open to inspection under Sect. 91 of the Acts, Feb. 29, 1948.] [Class 80(ii)] Two planetary trains, each providing a geared- and a direct-drive by a progressivelyacting clutch and brake, are arranged in series between aligned driving and driven shafts M1, R1, to provide four forward ratios, and in addition the connections between the trains, or between either train and its associated driving or driven shaft can be varied to produce, without using any additional wheels, reverse in one train, which may be a single reverse ratio or two such ratios using the other train. Stepped- or interengaging-planets or simple sun-ring trains are used in various combinations, controlled by electromagnetic friction disc clutches and brakes exclusively or with toothed clutches and one- or two-way detents for reverse. In Fig. 1 the first train has stepped planets carried by the driving shaft M1 and meshing reaction- and driven-suns A, B1, the latter, B1, constituting an intermediate member integral with the planetcarrier B11 of the simple sun-ring second train, the ring-gear of which is integral with the final driven shaft R1, while its reaction sun C can be held by an electromagnetic friction brake F2 for a geared overdrive, or clutched to its planetcarrier B11 for direct-drive by a similar clutch B10. A similar brake and clutch F1, M10 are provided in the first train for acting on the reaction sun A to provide reduced- and direct-drive, thus providing in all two forward reduced drives, direct- and overdrive, with the trains always in series. For the single reduced reverse a jaw-clutch C3, idle in all forward ratios, is moved to the left to clutch the reactionsun C of the second train directly to the driving shaft M1 through the planetcarrier of the first train. The planet-carrier B11 of the second train is then locked by engaging a pawl (not shown) with ratchetteeth B3 on the carrier, so that the second train drives alone in reverse, and all the other clutches and brakes are released. Fig. 2 provides four forward and two reduced reverse speeds using a simple sunring first train, and, for the second, stepped planets carried by the driven shaft R1 and meshing a reaction-sun C and a driving ring-gear B2, the latter integral with the intermediate member , B carrying the driven ring-gear B1 of the first train. In all forward speeds a jaw-clutch M2 clutches the first planet-carrier M to the driving shaft M1: the first train provides direct- and overdrive by an electromagnetic friction clutch and brake A1 between its reaction-sun A and driving carrier M; the second train providing reduced- and directdrive in the same manner. For reverse the jaw-clutch M2 is slid axially to the right to declutch the first planet-carrier M and clutch the reaction-sun A to the driving shaft M1 The carrier M is then held by engaging a pawl (not shown) with ratchetteeth M3 thereon, so that the first train drives reversely and, by using the clutch and brake Cl of the second train, two reversed ratios are obtained. Fig. 3 (not shown) is identical with Fig. 2 with the exception that the double ring-gear B is centred only rearwardly of the second train, as shown dotted in Fig. 2, the ring gear teeth B1, and B2 being then formed as one continuous set. In Fig. 4 (not shown) the functions of the reaction-sun C and ring-gear B2 of the second train are interchanged, which is possible without substantial alteration in overall ratio in that they are arranged to rotate at nearly equal speeds in opposite directions when the planet-carrier R is stationary. Fig. 5 (not shown) replaces the stepped-planet train of Fig. 2 by an interengaging planet-train with two unequal suns. Fig. 7 (not shown) arranges the stepped-planet train of Fig. 2 in front, with its ring-gear as reactionmember and its planet-carrier integrally driving the input ring-gear of the second simple sun-ring train, providing three forward geared drives, all reduced, in addition to direct. For reverse the reaction ring- gear of the first train is jaw-clutched to the reaction sun of the second and the planet-carrier of the first is held by a pawl (not shown) acting in one or both directions on ratchet teeth on the carrier. Fig. 9 (not shown) replaces the stepped-planet train of Fig. 7 by an interengaging planet train with driving and reaction suns. Fig. 10 (not shown) uses two simple sun-ring trains, the driven ring-gear of the first being integral with the driving sun of the second, the planets of which latter are carried by the driven shaft whilst its reaction ring-gear can be clutched to the planetcarrier or held by a brake. In the first train two brakes are provided for holding either the sun or the planet-carrier while the other is clutched to the driving shaft by either of two clutches, whereby the first train yields direct-drive (using both clutches together), overdrive and reverse. All the clutches and brakes are of the electromagnetic disc-type. Fig. 12 (not shown) modifies this arrangement by using an interengaging-planet second train with input and reaction suns.