Patent GB-697911-A (GB)
Title: Improvements in or relating to epicyclic change-speed gears
IPC: F16H3/66
Filed: 1950-07-25
Abstract: 697,911. Change - speed gear. RAVIGNEAUX, P. July 25, 1950 [July 28, 1949; July 8, 1950], No. 18594/50. Class 80 (ii). An interengaging planet-train, e.g. on a vehicle, providing three reduced ratios, directdrive and reverse, which may be combined with a complementary train yielding also overdrive or another reduced ratio, comprises two ring- gears R1, B, meshing through respective intermeshed planets S2, S1 with suns C, M1 respectively, the sun M1 being axially fixed and permanently fast on the input shaft M (or output other, with their hubs R2, B1, both located on on bell-shaped members nested one within the other, with their hubs R2, B, both located on the same side, i.e. the output side of the gear, and having dog-clutch teeth for selective engagement with a clutch-dog f, slidably splined on the output shaft R (or input shaft M), and at least three of the four elements comprised by the planet-carrier A, the two rings R1, B and the loose sun C are axially immovable. As shown all are axially immovable, permitting the use of helical gear-teeth. In addition the gapped or continuous planet S2 meshes the ring R, and sun C respectively in two radial zones which lie on either side of the single radial zone in which the planet S1 meshes the sun M1 and ring B, all three meshing zones being on the same side of the support-wall A of the planet-carrier. In all the many constructions shown, the dog f clutches to the output shaft R the ring B for the single reverse or the ring R1 for all forward ratios. The sun C is a brakeable reaction member and may also, in some cases, act as additional input member driven through the complementary train for the fifth ratio. Spring- retracted sliding electromagnetic or mechanical friction brakes may be used and the dog clutch f may be moved into its three positions (forward, neutral and reverse) by separate electromagnets acting on a common lever (Fig. 3, not shown). In Fig. 1, with the ring-gear Rl dogclutched to the output shaft R, the main train alone provides first, second and third reduced ratios by braking respectively the main planetcarrier A at E2; the ring B at E3; and the reaction sun C at E; and direct drive by clutching at P the reaction sun C to a reaction sun G1 in the complementary train. The latter includes also a simple planet-carrier A integral with that A of the main train, and a ring-gear C2, the compounded overdrive being obtained by braking the reaction sun G1 at E1, which causes the main reaction sun C to be driven forwardly at a higher speed than the main input sun MI. Reverse is by dog-clutching the ring B to the output shaft R and braking the planet-carrier A at E2. All the brakes and the direct-drive clutch are electromagnetic with spring-retracted members, e.g. windings E or armatures N2, axially slidable in relation to their associated members which are thus not required to move' axially. The input and output shafts M, R, which may exchange functions, may both be arranged on the same side of the gear, as shown dotted in Fig. 1. A modified main train, Figs. 3, 4, 5 and 7 (not shown), uses a reaction sun C smaller than the input sun M1, together with an ungapped long planet, whilst Fig. 2 (not shown), has ring- gears B and R1 of equal size, the planet pinion Sl being gapped instead of S2. Modifications of the complementary fifthspeed train comprise (1) using interengaging planets carried either by the main planet-carrier, Fig. 2 (not shown), or by the input shaft, Fig. 9 (not shown) together with a second sun, permanently connected to the reaction sun of the main train, and a braked reaction sun; and (2) arranging the complementary train at the output side of the main train, Fig. 7 (not shown), with simple long planets carried by the main reverse ring-gear B, a sun integral with the main forward ring-gear R1, and a brakeable reaction ring-gear, arranged axially spaced from the sun to permit the flange of the main ring-gear B, carrying its clutch dogs, to be interposed therebetween. Many of the constructions show brake-drums for use with mechanical band-brakes, and directdrive cone clutches between various different elements. In Fig. 5 (not shown), which omits the complementary train and hence provides only four ratios and reverse, the three brakes are of the single or multi-disc type, actuated by turning two screw-members in internal threads in the fixed casing, one such member being screwed in opposite directions to actuate two of the brakes, whilst the other is similarly screwed to operate one brake in one direction and, through a thrust-bearing and radial levers, engages the direct-drive disc clutch in the other. The screwed members are turned by double-acting hydraulic or pneumatic pistons operating, through levers and pinions, on gear teeth on the members, Fig. 6 (not shown). In all cases the numbers of teeth on the wheels and the resulting numerical gear ratios are stated.