Motor vehicles – Transmission mechanism – Assembly feature
Reexamination Certificate
1999-08-19
2001-05-08
Swann, J. J. (Department: 3611)
Motor vehicles
Transmission mechanism
Assembly feature
C180S053400, C180S235000, C180S336000, C180S242000, C180S246000, C180S306000, C180S307000, C180S367000, C180S383000
Reexamination Certificate
active
06227326
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to four wheel drive articulated tractors and, more particularly, to improvements to the drive system for hydrostatically driven tractors.
It is desirable to integrate all the drives for the input driven components of an articulated four wheel drive tractor into a single gearbox affixed to the rear axle housing of the tractor. Such a mechanism would place the hydrostatic pump for powering the traction drive of the tractor, the hydraulic pump for the tractor hydraulic system, the drive for the power-takeoff (PTO) system, and any auxiliary hydraulic pumps to be driven off the same gearbox device with the output driver components, including the hydrostatic motor, speed reduction gears and output drive shafts.
Lubrication of a gear set is a consideration in the design of a gearbox device for transferring rotational power through gear sets arranged and configured to provide the proper rotational speed to a component driven from the engine of the tractor. Commonizing lubrication sumps can minimize the number of lubrication systems that need to be provided as well as provide more effective lubrication of the gear sets and the cooling of the lubrication fluid.
Conventional tractor drive mechanisms include a mechanical transmission to provide different output speeds for a given engine input speed. Even hydraulically driven tractors have utilized a three speed mechanical transmission between the engine and the hydrostatic pump to provide desired different input speeds to the operation of the hydrostatic pump for powering the movement of the tractor. It would be desirable to replace the three speed mechanical transmission on hydrostatically driven tractors to minimize cost and to enhance operation of the tractor.
The gearbox would preferably be configured to mount the auxiliary pump drive mechanism in an optional manner so that the auxiliary pump could be added to the gearbox, if desired, and be driven therefrom.
SUMMARY OF THE INVENTION
It is an object of this invention to integrate the drive mechanisms for a hydrostatically driven, four wheel drive tractor in which all the drives are driven from a single splitter gearbox.
It is a feature of this invention that the splitter gearbox is affixed to the rear axle housing of the tractor.
It is an advantage of this invention that the mounting of the splitter gearbox to the rear axle housing allows the splitter gearbox and the rear axle housing to share a common oil sump.
It is another advantage of this invention that the mounting of the splitter gearbox to the rear axle housing reduces complexity.
It is another object of this invention to drive the front and rear axles of a four wheel drive tractor from a variable displacement hydrostatic motor.
It is another feature of this invention that a hydraulically driven tractor need not have a conventional transmission in order to obtain customary speed ranges desired for a tractor.
It is still another feature of this invention that the variable displacement hydrostatic motor can be provided with a selected number of pre-set swash plate positions to effectively replace a conventional transmission gearbox.
It is another advantage of this invention that the fixed positions of the variable displacement hydrostatic motor, coupled with a variable speed hydraulic pump, can be controlled electronically to provide a smooth power-shifting operation.
It is still another advantage of this invention that the tractor does not require stopping to shift gears in order to change the range of operation of the tractor.
It is another feature of this invention that the splitter gearbox incorporates a gear drive system in association with the hydrostatic motor to provide a shaft extending forwardly and rearwardly out of the splitter gearbox to drive, respectively, the front and rear axles of the tractor.
It is still another advantage of this invention that the front and rear axles of the four wheel drive tractor are driven from a single hydrostatic motor.
It is still another object of this invention that the input drive train and the output drive train are incorporated into a single splitter gearbox.
It is yet another object of this invention to provide an auxiliary pump drive for a four wheel drive tractor.
It is still another feature of this invention that the auxiliary pump drive can be mounted as an option to the side of the splitter gearbox.
It is yet another advantage of this invention that the auxiliary pump can be driven from an idler gear appropriately positioned within the splitter gearbox.
It is a further object of this invention to provide a splitter gearbox for a four wheel drive, hydrostatically driven tractor which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use.
It is still a further object of this invention to provide an auxiliary drive mechanism that can be mounted on a splitter gearbox for a four wheel drive, hydrostatically driven tractor, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use.
These and other objects, features, and advantages are accomplished according to the instant invention by providing a splitter gearbox for a four wheel drive, hydrostatically driven tractor in which the input drive train and the output drive train are integrated into a single gearbox. The drive mechanism eliminates the need for a separate mechanical gearbox by establishing pre-set fixed displacement settings that are electronically controlled along with the variable displacement of the hydrostatic motor and hydrostatic pump, to provide a smooth power shift through all ranges without requiring the tractor to stop. The drive mechanism is configured so that essentially all components are individually controlled so that the entire power generated by the tractor engine can be diverted to any one of the traction drive, the PTO mechanism, the auxiliary hydraulic drive or, to a somewhat lesser extent, the tractor hydraulic system. The splitter gearbox is mounted to the rear axle housing to allow the sharing of a common oil sump. The input gear set and the output gear set are also within the same common lubrication sump within the splitter gearbox.
REFERENCES:
patent: 3687212 (1972-08-01), Forster
patent: 3913697 (1975-10-01), Greene
patent: 4399886 (1983-08-01), Pollman
patent: 4579183 (1986-04-01), Irikura et al.
patent: 5137106 (1992-08-01), Allen et al.
patent: 5560447 (1996-10-01), Ishii et al.
Chorney Harvey J.
Kowalyk Vladimir M.
Young David A.
Miller Larry W.
Mitchell John B.
New Holland North America Inc.
Stader John William
Swann J. J.
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