Multiple-step gear drive

Machine element or mechanism – Gearing – Interchangeably locked

Patent

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Details

74352, 74329, 74397, F16H 334

Patent

active

048874787

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a multiple step gear drive comprising a first stationary toothed wheel rotatable about a first shaft, a second stationary toothed wheel spaced from the first toothed wheel and rotatable about a second shaft, one gear train for each gear ste, each gear train consisting of a gear-wheel or of several drive-connected gear-wheels, all the gear-wheels being rotatably journalled in a housing movable substantially perpendicular tos aid first and second shafts to be brought into a specific engagement position of each gear step in which the gear train is in engagement with the first and second toothed wheels.
Conventional gear drives permitting multiple step gear changing generally comprise a plurality of parallel, rotatable shafts on which a number of toothed wheels are mounted to transmit driving torque. Some shafts are provided with axially displaceable gear-wheels, secured by splines, for instance, to prevent relative rotation. When changing gear, the gear-wheels are displaced along the shafts and brought into or out of engagement with axially immovable toothed wheels. Such gear drives require considerable space in all directions since there must be spaced both for the toothed wheels and for the above-mentioned displacement of the gear-wheels perpendicular to the main extension of the toothed wheels. It is therefore impossible to use such gear drives when the available space is relatively limited. Furthermore, this arrangement is rather complicated and expensive. The mechanism for moving the gear-wheels, for instance, must be executed with great precision, and the degree of complexity increases the more gear steps are included.
A multiple step gear drive is already known through SE-C-118 558. This is composed of a plurality of small gear drives, each corresponding to the gear defined in the introduction. This known gear thus comprises a drive and two gear-wheels housed in a housing pivotable about the pivot shaft of the drive. Rotation of the housing enables the gear-wheels to be brought into engagement with a totthed wheel secured on the driven shaft so that it cannot rotate. The gear-wheels engage one on each side of the connecting plane between the turning shaft of the housing and the pivot shaft of the driven shaft. When one of the gear-wheels is turned to engage, the other will be disengaged and vice versa. Only two gear changes are possible with a fixed axial position of the housing. In this known gear drive, the number of gear steps is increased by the housing and the gear-wheels also being displaceable parallel to the turning shaft and pivot shafts respectively. This type of gear drive with more than two steps thus takes up a considerable amount of space even in the axial direction of the toothed wheels and cannot therefore be used when the space available is limited.
The object of the present invention is to effect a multiple step gear drive comprising several gear steps but which takes up little space in one direction, while at the same time having a simple construction and consequently low manufacturing cost.
This is achieved in a gear drive of the type described in the introduction in that in at least one hear step the housing can be disengaged from its engaged position in two substantially opposite directions, thus moving the corresponding gear train in the selected direction and thereby breaking the driving connection between the first and second toothed wheels, established in said engagement position.
The invention will be described in more detail in the following with the aid of two embodiments and with reference to the accompanying drawings in which
FIG. 1 shows schematically from above a first embodiment of a gear drive according to the invention, with certain components removed for the sake of clarity,
FIG. 2 shows a longitudinal section along the line II--II in FIG. 1, with a first gear-wheel in engagement position,
FIG. 3 shows a londitudinal section corresponding to that in FIG. 2, with a second gear-wheel in engagement position,
FIG. 4 shows a longitudinal section

REFERENCES:
patent: 209833 (1878-11-01), Perrin
patent: 276463 (1883-04-01), Powell
patent: 1380021 (1921-05-01), Robinson et al.
patent: 1981428 (1934-11-01), Schneider
patent: 2662417 (1953-12-01), Mascherpa
patent: 3367200 (1968-02-01), Cummings
patent: 4315438 (1982-02-01), Stephenson
patent: 4582171 (1986-04-01), Jezierski

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