Machine element or mechanism – Gearing – Interchangeably locked
Patent
1995-08-10
1998-05-12
Ta, Khoi Q.
Machine element or mechanism
Gearing
Interchangeably locked
74333, 74339, 192108, F16H 3093
Patent
active
057492638
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a toothed-wheel gear change with power distribution over several layshafts, a coaxial input shaft radially and axially supported and an output shaft (main shaft) which is floating, wherein at least one input gear provided upon the input shaft transmits the torque to gears meshing therewith and firmly secured to said layshafts, the loose gears being axially secured but radially free upon the input and output shafts.
In transmissions of this kind having at least two layshafts, the load compensation is in general such that the input shaft and the layshafts are rigidly supported with respect to the housing while the main shaft or output shaft is floating in the summation gears situated thereon which are in the power flow.
In the presence of two or more constants, the problem arises that in the case of several input gears the input gear not engaged requires radial play due to manufacturing tolerances. When a torque diminishes on a layshaft, radial and axial forces result in a helically cut meshing of teeth on the input shaft. To be able to absorb them, the gear that is in the power flow must be guided toward the input shaft.
Layshaft gear changes are generally designed in a manner such that the input shaft is firmly radially and axially supported while the main shaft or output shaft, on account of the required load compensation, is radially free and only axially fixed. But the inverse design or shaft mechanism is basically possible also.
All loose wheels on the input shaft and on the output shaft are only axially fixed but radially free for a functioning load compensation.
However, the necessary load compensation is disturbed, or an operation of the toothed-wheel gear change is not at all possible, when an asymmetrical intensity of force occurs. This is the case, for instance, when a power take-off has to be effected via one layshaft only. This means that the toothed-wheel gear change of the above mentioned kind is not suited to such a function.
This invention, therefore, is based on the problem of providing a toothed-wheel gear change of the kind mentioned above which also allows an asymmetrical intensity of force, especially one where a power take-off is also possible via one layshaft only.
According to the invention this problem is solved by the fact that the input gear is radially fixable by a movable securing device.
An asymmetrical force intensity or a one-sided output over one layshaft is possible by radially fixing or centering the input gear situated upon the input shaft without impairing the operating capacity of the toothed-wheel gear change.
The securing device will be advantageously coupled with the shifting device for the input gear.
In this manner, a shiftable radial fixing which makes possible two shifting positions is obtained. At least two input gears are generally present, but it is always only the input gear that has to be radially fixed for operating capacity. The respective other input gear must be radially free.
However, the number of shiftable fixings is not basically limited.
A simple, practical design of the securing device or of the ramp can consist in designing the ramps as a diameter reduction of the input gear beneath which an axial extension of the sliding sleeve is movable for the axial fixing.
By means of said design, a radial fixing of the input gear is simultaneously provided when coupling or connecting the torque of the input gear with the input shaft.
In order to obtain a perfect torque transmission and prevent tilting of the input gear, it can be provided that the diameter reduction extends axially beyond the center of meshing of the teeth.
A very advantageous further development of the invention consists in the securing device forming, at the same time, the torque-transmitting device.
The torque is transmitted from the input shaft to the layshaft in a manner known per se via a coupling gearing between the sliding sleeve and the input shaft. According to the invention, said gearing is now simultaneously used for the centering or radial fixing of the i
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Bader Josef
Buri Gerhard
Ta Khoi Q.
ZF Friedrichshafen AG
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