GB813872A - Improvements in change speed gearing - Google Patents

Abstract

813,872. Change-speed gear. VOREAUX, P. J. Feb. 18, 1957 (Feb. 22, 1956], No. 5501/57. Class 80 (2). In an automatic three-element planet train, for a motor vehicle, having input and output suns 1, 2 and a reaction carrier 4 for stepped planets, wherein the reaction carrier 4 is, in reduced drive, prevented from reverse rotation as by a oneway detent 6, or controllable positive stop, and carries centrifugal clutch shoes 7, which, when the reaction carrier 4 is caused to rotate forwards above a predetermined speed by momentary torque reversal, as by throttling the driving engine, clutch an input drum 12 to upshift to direct solid drive, with fully automatic return downshift by clutch release when the speed falls, the torque reversal which initiates this upshift is caused automatically by a centrifugal, hydraulic or electric engine-speed sensing device, modulated, if desired, by engine load, as sensed by enginethrottle opening. Where the reaction member 4 is held by a controllable positive stop, this may be released by the torque-reversing means, which may also be used to produce automatic declutching. The torque reversing means is rendered inoperative in direct drive. In Fig. 8, not shown, two (or more) such gear trains are used in series to provide four (or 2<SP>n</SP>) ratios, the trains being so designed that both change simultaneously in shifts between second and third ratios. The automatic torque-reversal device, with direct drive suppression, Fig. 7, comprises centrifugal masses 20a driven by the engine through helical gears 24a, 24b and acting leftwards, when the desired upshift speed is reached, through a rod 21a to cut off directly, hydraulically, or electrically, the engine fuel supply in opposition to a spring 22a adjustably compressed by the usual engine accelerator pedal or pressure fluid controlled thereby. The fuel supply is restored when the masses collapse on engine deceleration, and after the upshift any further fuel cut-off is prevented by the torque reversal suppressor which comprises two plates 26a, 27a held together by non-rotary flanges 30a, one plate 26a being screwed at 28a on an axially fixed rod 19a pinned to the enginedriven helical wheel 24b, whilst the other plate 27a has an axially free drive connection with a helical wheel 25b driven through a wheel 25a by the output shaft 2 of the gear, the ratios of the gear pairs being so chosen that the wheel 25b rotates faster than 24b in direct drive and slower in reduced drive. Thus, in reduced drive the assembly occupies the ineffective position shown, whilst in direct drive the speed difference screws the plate assembly leftwards along the thread 28a, taking up the clearance b and taking along a rod 31a, which acts on the torque-reversing means directly or through hydraulic or electric means, to prevent its operation.