Patent GB-460764-A (GB)
Title: Improvements in variable speed transmission mechanism
IPC: F16H47/08
Filed: 1935-04-29
Abstract: 460,764. Hydro-mechanical variablespeed gearing. DODGE, A. Y. April 29, 1935, No. 12756. Convention date, April 30, 1934. [Class 80 (ii)] A variable-speed transmission' suitable for vehicles comprises a planetary train T, Fig. 1, and a three-vaned-element hydraulic torque converter H in which during automaticallyvarying forward driving there is a two-path simultaneous flow of power in parallel from an input shaft 50 to an output shaft 64 with the converter H in one path. In the arrangement of Fig. 1, the train T is moved axially by hand through a lever 67 to change between automatic forward, positive low-speed forward, neutral, and positive reverse. The positive forward drive is one step to the right from the neutral shown to bring teeth 60 into mesh with teeth 59 and teeth 65 into mesh with teeth 80 on the output shaft 64. The train T is, as shown in Fig. 6, one with interengaging planets 200, 201 in which when a sun 63 drives and the carrier 89 of the planets is held fast, the annulus 95 is driven forwards at reduced speed. The teeth 65 are on this annulus. The converter H shown is one in which a solid high-speed drive is effected although the stator 92 is fixed absolutely against rotation as described in Specification 460,838, [Group XXIX], the liquid circulating clear of the stator 92 which is rigid with a casing 90. The impeller 53 is rigid with the shaft 50. The rotor 54 is connected through a sleeve 55 to a muff 56 with the clutch teeth 59. The rotor 54 is thus connected, in this position, through a sleeve 61 to the planet carrier 89. The sun gear 63 is driven direct through a shaft 62 and coil clutch 83 from the input shaft 50. The clutch 83 is adapted to yield if, in descending a hill, bhe engine should jam. There is thus a two-path flow of power to the driven annulus 95 in one of which is the converter H. The muff 56 is prevented from turning backwards by one-way rollers 57 engaging a track 58 adapted to be connected by friction plates 87 to the fixed casing 90. This is instrumental in starting a vehicle. In low speed, the train T is moved right a step farther to bring the teeth 60 into engagement with teeth 72 on the track 58 while the teeth 65 on the annulus 95 remain engaged with the driven teeth 80. The reaction of the drive of the pinion 63 on the slow-driven annulus 95 is taken by the carrier 89 supported on the track 58 through the clutch 60, 72, provided the plates 87 are engaged. This low-speed drive can be engaged and disengaged by a pedal arranged like a main clutch pedal to operate the plates 87 against springs 100. This low-speed drive is positive, the converter H running idly. Reversed drive is also positive being produced by sliding the train T left of neutral so as to engage teeth 73 on the annulus 95 with the fixed reaction teeth 72 and to engage teeth 74 on the carrier 89 with the teeth 80 of the driven shaft 64. On the rightward swing of the control 67 for forward drives, the engagement of the clutch teeth 60, 59 &c. is facilitated by coned surfaces 77. In Fig. 2 is shown a cushion drive adapted to be interposed between the clutch teeth 66 and the shaft 64. A heavy coil spring 22 is supported at its ends between two drums 121 and 123 so that it may wrap on the former or be expanded hard against the latter. In an alternative form shown in Fig. 3, the converter H again has a stator 92 fixed absolutely to a casing 90. The drive disengaging pedal in this case frees a band brake 134. There is a centrifugal clutch at 135 between the two rotary members 53 and 54 of the converter to aid the solid drive. In the train T, as shown in Fig. 7, there is another centrifugal lockable shoe 217 for the same purpose. The planets 200 and 201 are eccentrically loaded at 215, 216, still for the same purpose. The planets also act as a gear pump, sucking oil up a pipe 143, Fig. 3, in at ports 225 and driving it out at ports 226 and through a lubricating system. Central clutch teeth such as 72, 194, Fig. 4, are synchronized by an interposed split spring ring 75. The drive to the pinion 53 may be disengaged at 140, Fig. 3, by manual effort on a collar 139. A form of converter with fixed stator combined with a centrifugallyclosed multiple plate clutch suitable for substitution in the arrangements of Figs. 1 and 3 is described with reference to Fig. 8 (not shown). The stator is adapted to be freed for solid rotation by hydrostatic pressure. This arrangement is described in Specification 460,838. In a further complete arrangement described with reference to Fig. 12 (not shown) the converter is an ordinary form in which the stator is free to turn forwardly ; the planetary gearing comprises separate trains and the converter is operative on reversed drive. Fig. 10 shows a cam interlock 490 by which the manual change lever 493 is brought to neutral when a lever 491 is robated to apply the vehicle brakes. The lever 493 may alternatively be the drive-disengaging lever. Fig. 11 shows an interconnection by which depression of a vehicle brake pedal 497 shifts a rod 499 right to close the engine throttle. The Specification as open to inspection under Sect. 91 comprises also the subject-matter of Specification 460,838. This subject-matter does not appear in this Specification as accepted.