Motor vehicles – Power – Including traction motor of kind driven by noncompressible...
Reexamination Certificate
2000-02-01
2001-10-23
Hurley, Kevin (Department: 3619)
Motor vehicles
Power
Including traction motor of kind driven by noncompressible...
C180S242000
Reexamination Certificate
active
06305486
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
Utility vehicles are commonly used on farms, ranches and construction sites for sportsman's applications transporting cargo over a variety of terrain. Prior utility vehicles have employed mechanical drive systems in which the output of the engine drives the wheels through a mechanical linkage such as a chain, belt or drive shaft. As a result these vehicles have been costly and complicated to manufacture and maintain. It is particularly high maintenance to provide four-wheel drive in these vehicles when a mechanical drive is employed. Hence, it is desirable to provide hydrostatic drive that can be used in these small utility vehicles. It is also desirable to provide such a vehicle with a hydrostatic (power) steering system.
BRIEF SUMMARY OF THE INVENTION
One object of the present invention is to provide a hydrostatic drive system for a utility vehicle.
Another object of the present invention is to provide a two-wheel hydrostatic drive system for a utility vehicle.
Yet another object of the present invention is to provide a four-wheel hydrostatic drive system for a utility vehicle.
A further object of the present invention is to provide a hydrostatic steering system for a utility vehicle.
Still another object of the present invention is to provide a hydrostatic drive system that is simple and economical to manufacture and maintain.
These and other objects are provided by a hydrostatic drive for a utility vehicle which includes a variable rate hydrostatic pump driven by a prime mover. In a two-wheel drive system, hydraulic fluid from the pump is split evenly between the rear motors. The flow turns the motors, exits the motors and is then directed back to the pump. In a four-wheel drive system, the hydraulic fluid flow from the pump is split evenly and directed to the front wheel motors. This flow turns the front wheel motors and then exits the wheel motors. The flow exiting the front motors is directed to the rear wheel motors on the opposite sides of the vehicle. The flow exiting the rear motors is then directed back to the pump. The hydrostatic drive does include a neutral valve interconnected between the pump and the motors. The neutral valve is movable between a first position at which fluid flow output from the pump bypasses the motors and is redirected to the pump, and a second position at which the output flow from the pump is directed to the hydraulic motors. The hydrostatic drive does include a flow control valve interconnected between the pump and the motors and being adapted to bypass fluid flow around the motors until the rate of flow from the pump reaches a predetermined level.
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patent: 6119802 (2000-09-01), Puett, Jr.
Polzin Keith M.
Van Voorst Gene A.
Hurley Kevin
Koyker Manufacturing Company
McAndrews Held & Malloy Ltd.
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