Machine element or mechanism – Gearing – Interchangeably locked
Patent
1987-03-03
1988-10-18
Wright, Dirk
Machine element or mechanism
Gearing
Interchangeably locked
74333, F16H 308
Patent
active
047778377
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a transmission for motor vehicles with internal combustion engines, especially farm tractors. In such a transmission it is possible to shift under load from one speed to another speed, an during a change of speed to transfer uninterrupted power from the drive shaft.
In known transmissions of this type (German OS 32 28 353, FIG. 3) friction clutches are disposed on two secondary shafts between a secondary shaft and a main gear group and a secondary of an inner gear group. The two friction clutches must be large enough to transmit torque of the drive motor increased by the torque transmission of the first or second gear step of the main gearing group.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
The object of the invention is to provide a power shiftable transmission for vehicles, especially farm tractors, with a total driving speed range from about 1 km/h to about 50 km/h, with a speed step of about 1.2 with in main speed range from about 4 km/h to about 12 km/h, with a speed step of about 1.4 within a crawl speed range and a transport speed range, and with a minimum of speeds, gears, claw clutches and only two power shiftable friction clutches.
The invention also provides a reduction in size and cost of the two friction clutches. Because the two friction clutches are disposed on a main axis of the transmission they need only transmit the torque of the drive motor. Therefore, such clutches may be small. Further, the cost of the two friction clutches is reduced since they have common components.
Accordingly, the invention provides: a lower range of travel speed with large progressive ratios, a medium range of travel speed with small progressive ratios and an upper range of travel speed with large progressive ratios.
That is particularly advantageous for a tractor which must produce the greatest part of its work in a medium range of travel speed between 4 km/h and 12 km/h. In this usual travel speed range such a tractor is to have a high degree of performance-service, defined as the ratio of the actual performance to the maximum performance, and/or a high effective degree of operation, defined as the ratio of the useful work to consumption of fuel, while the degree of service and the degree of effectiveness in the case of travel speeds below 4 km/h and above 12 km/h are less important.
The degree of performance-service in the usual travel speed range is very high especially since the output shaft is then connected directly with a second auxiliary shaft.
The invention makes it possible to have for each forward speed a reverse speed and for each forward range a reverse range, because the reverse gearset of the reversing gear may form a reversing rpm for each forward rpm of the output shaft. The reversing rpm may be smaller, equal to or larger than the pertinent forward rpm because the number of teeth of the idler on the output shaft may be freely selectable within wide limits and the numer of teeth of the reverse gear may be selected.
The arrangement provides three range gear groups and a reversing gear group with only three sets of gears having only eight gears.
In construction, a power take off is disposed on the driven side of the gearing at low cost since the drive shaft may be mounted in three hollow intermediate shafts all on a common axis.
Construction cost is particularly low because components may be designed identically for the two friction clutches and two intermediate shafts, and thus a greater number of production pieces may be achieved for many construction parts at reduced costs.
A power path take off disposed on the driving side may be made at particularly low costs because the output shaft is mounted in a hollow second auxiliary shaft. In a motor vehicle with a main drive shaft an additional drive shat may thus be driving in a particularly advantageous manner, for example, a live steering shaft in a tractor.
Construction costs may be reduced further since the number of gears and gear sets is reduced an thus the overall length and weight of
REFERENCES:
patent: 2991661 (1961-07-01), Rambausek
patent: 3301079 (1967-01-01), Fletcher et al.
patent: 3682019 (1972-08-01), Hoyer et al.
patent: 4023418 (1977-05-01), Zenker
patent: 4226135 (1980-10-01), Winter
patent: 4579015 (1986-04-01), Fukui
patent: 4580459 (1986-04-01), Zenker et al.
Wright Dirk
Zahnradfabrik Friedrichshafen AG.
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