Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Patent
1990-10-17
1992-02-04
Wright, Dirk
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
74335, F16H 6344
Patent
active
050850954
DESCRIPTION:
BRIEF SUMMARY
This invention relates to gearbox selector mechanisms and in particular such mechanisms which require the sequential operation of separate couplers within the gearbox by a single selector member. An example of such a mechanism is in a tractor gearbox where speed change couplers and range change couplers are required to be operated by a single selector member in the form of a gear lever.
Various selector mechanisms have been proposed for such applications. For example, the mechanism disclosed in United Kingdom patent number 1546461. However such mechanisms have produced relative complex gear lever shift patterns as shown by the double H-shift pattern of the above patent.
It is an object of the present invention to provide a selector mechanism suitable for a gearbox in which a single selector member controls both speed and range changes and in which a simple selector member shift pattern is achieved.
Thus according to the present invention there is provided a selector mechanism for a gearbox in which one or more speed change couplers and one or more range change couplers are operated by the same selector member, said selector member operating the speed change coupler or couplers to engage a plurality of drive speeds when moved from a neutral plane to speed selection positions in a speed change gate and operating the range change coupler or couplers when moved to discrete range change positions, the mechanism being arranged so that on movement of the selector member out of the speed change gate towards a desired range change position the appropriate range change coupler is moved towards an engaged position for the desired range and on movement of the selector member back towards the speed change gate from the desired range change position the movement of the said appropriate range change coupler is completed to engage the desired range.
In a preferred construction an H-shaped gate is used for the speed change gate with the neutral plane bridging the arms of the H and the range change positions are provided in a plane parallel to the two speed change arms of the H reached by an extension of the neutral plane of the H, the selector mechanism being arranged to move the appropriate range change coupler towards said engaged position on movement of the selector member along the extension of the neutral plane during movement of the selector member towards the range change plane, during movement of the selector member towards the appropriate range change position in the range change plane, and on movement of the selector member back along the extension of the neutral plane on its way back to the speed change gate.
The movement of the appropriate range change coupler as the selector member moves along the neutral plane extension towards the range change plane may be achieved by contact between a first component moved by the selector member and a first cam formation associated with the appropriate coupler and the movement of the coupler during the return movement of the selector member back along the extension of the neutral plane may be achieved by contact between a second component moved by the selector member and a second cam formation associated with the appropriate coupler.
The first component may be a selector finger which is moved by the selector member to engage selector formations associated with the speed and range change couplers and the second component may comprise an interlock member moved by the selector finger to allow movement of only one coupler at a time.
In a preferred construction the speed and range change couplers are operated by selector forks mounted for sliding movement on a single rail and the interlock member is mounted for pivotting about said single rail.
One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a vertical section through a tractor transmission which is controlled by a selector mechanism in accordance with the present invention;
FIG. 2 is a plan view of part of the selector mechani
REFERENCES:
patent: 4615233 (1986-10-01), Lasoen
patent: 4920815 (1990-05-01), Reynolds
Massey-Ferguson Services N.V.
Wright Dirk
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