Patent ID: 7121374

Claim:
An agricultural combine comprising: a. a chassis; b. an internal combustion engine mounted on the chassis; c. a rotor configured to thresh agricultural plant matter, the rotor coupled to the engine to be driven thereby; d. a header fixed to the front of the chassis and disposed to gather and cut the agricultural plant matter; e. a ground drive system including: i. a variable displacement hydraulic pump coupled to the engine to be driven thereby; ii. four variable displacement hydraulic motors coupled together in parallel to one another and coupled in series with the hydraulic pump to be driven by the pump; and iii. four ground-engaging wheels, each wheel coupled to an associated one of the four hydraulic motors to be driven thereby; and f. an electronic control system including: i. four speed sensors, each sensor disposed to sense the rotational velocity of a corresponding one of the motors or a corresponding one of the wheels; ii. a means for determining the speed of the vehicle, wherein the means for determining is a sensor selected from the set consisting of a ground-reflective radar and a radio navigation receiver; and iii. an electronic controller coupled to the four speed sensors, and the means for determining and configured to limit the slippage of each of said four wheels individually by controlling the specific displacement of a motor drivingly coupled to said each of said four wheels, wherein the electronic controller is configured to compare a vehicle speed provided by the means for determining and to compare the vehicle speed provided by the means with speed signals from each of the four speed sensors, and to vary the specific displacement of each of the four wheels based upon results of those comparisons, wherein the electronic controller is configured to determine whether each of the four wheels is slipping and to responsively reduce the specific displacement of a motor coupled to said each of the four wheels in response.