Machine element or mechanism – Gearing – Interchangeably locked
Patent
1998-07-16
2000-02-08
Wright, Dirk
Machine element or mechanism
Gearing
Interchangeably locked
74333, F16H 308
Patent
active
060216840
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a motor vehicle gearbox, comprising at least one input shaft, at least one lay shaft, gears carried by the input shaft and the lay shaft, said gears engaging each other to transmit torque from the input shaft to the lay shaft, an output shaft and gears which are carried by the lay shaft and the output shaft and which interengage in pairs to transmit torque from the lay shaft to the output shaft, at least one gear in each pair being a releasable free gear, either the input shaft or the output shaft being provided with an axial, cylindrical and concentric bore opening at a shaft end facing the shaft end of the other shaft, said other shaft being provided with a shaft end which extends into and is carried in the bore.
BACKGROUND OF THE INVENTION
SE-8802885-7 describes as previously known a gearbox of this type having two concentrically journaled input shafts, arranged to be driven alternately, and two lay shafts driven by said input shafts and having gears in engagement with gears on an output shaft. The inner input shaft is mounted in a roller bearing which is held in a bearing seat in a wall of the gearbox housing, and is provided with an axial bore into which there extends a shaft end of the output shaft. The proximal end of the shaft end is mounted in a roller bearing mounted in the bore and lies in the same radial plane as the proximal bearing of the input shaft, i.e. in the intermediate wall. The outer input shaft is mounted on the inner input shaft via an intermediate bearing which is disposed on the input side of the gearbox relative to the housing wall. The output shaft is in this manner journaled in the gearbox housing at both ends at the same time as the inner input shaft can be dimensioned with very little inner overhang, which eliminates the risk of excessive deflection of the two shafts.
The disadvantage of the arrangement described is, however, that the housing wall requires a certain amount of axial space making the gearbox longer and heavier than if the housing wall could be eliminated. A further disadvantage is that the lay shaft packages cannot be completely pre-assembled prior to installation in the gearbox housing, since they carry components which are to lie on either side of the housing wall. In this known gearbox, a central synchronization device on one lay shaft lies on the outside of the housing wall, while the rest of the components lie on the inside of the housing wall. On the second lay shaft outside the housing wall, there is a gear engaging a gear of the outer input shaft while the rest of the components lie inside the housing wall.
SUMMARY OF THE INVENTION
The purpose of the present invention is, in a gearbox of the type described by way of introduction to achieve a shaft bearing arrangement which eliminates the need for a housing wall without creating problems with excessive deflection of the input and output shafts.
This is achieved according to the invention by virtue of the fact that said shaft end is carried in the bore at at least two axially spaced bearing points. By bearing one shaft in the other with double bearings, the shafts are relieved of load without having to use an intermediate wall. This in turn means that the length and weight of the gearbox can be reduced and that the lay shaft packages can be pre-assembled completely prior to installation in the gearbox housing.
In a preferred embodiment of a gearbox with double concentric input shafts and double lay shafts, the bore is made in the output shaft and the shaft end portion is made on the inner input shaft. At the opening of the bore therein the output shaft has a bearing seat of greater diameter than the remaining portion of the bore in the output shaft and said seat can hold a bearing of various sizes adapted to the difference in diameter.
The inner input shaft, in front of its gear engaging the associated lay shaft, is mounted in two bearings against the outer input shaft, which in turn is carried in the gearbox housing.
BRIEF DESCRIPTION OF TH
REFERENCES:
patent: 1756917 (1930-04-01), Tenney
patent: 1780460 (1930-11-01), Burnett
patent: 2475803 (1949-07-01), Probst
patent: 2633753 (1953-04-01), Campodonico
patent: 4252223 (1981-02-01), Morscheck
patent: 4329885 (1982-05-01), Morscheck
AB Volvo
Wright Dirk
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