Abstract: A hydraulic system (20) for controlling the seed/fertilizer supply system (10) and the down pressure on a plurality of individual row units (12). A secondary supply arrangement (60) interconnects a first control circuit (26) of supply system (10) with a second control circuit (28), when the row units (12) are in a float mode, to provide pressurized fluid for the down force on the row units (12) during operation.

Abstract: A steering traction control apparatus for a track laying work machine includes first and second speed sensors that produce a slip signal responsive to the difference in rotational velocity of first and second axles. A controller receives the slip signal and responsively supplies a steering output signal in response to the magnitude of the slip signal.

Abstract: A device for controlling an electro-hydraulic differential steering system of a work machine. A first processing device receives a first signal indicative of a desired steering path, a second signal indicative of a ground speed, a third signal indicative of an engine speed, and a fourth signal indicative of a gage. The first processing device transmits a fifth signal as a function of the first, second, third, and fourth signals, the fifth signal being indicative of a desired pump displacement of the steering system. A second processing device receives a sixth signal indicative of a motor speed of the steering system, and the third signal. The second processing device transmits a seventh signal as a function of the third and sixth signals, the seventh signal being indicative of an actual pump displacement of the steering system.

Abstract: A rotary control valve includes a directional control valve having a rotatable valve element for controlling the direction of fluid flow from an input passage to a pair of control ports and from the control ports to a drain passage. A pressure regulating valve is connected to a source of pilot pressure and has a valve spool for controlling the regulated pressure level of pilot fluid in the input passage. A cam is connected to the valve element for unitary rotation therewith. A spring and a plunger are disposed between the valve spool and the cam so that the valve spool is mechanically moved in a rectilinear direction by the cam in either direction from a neutral position to increase the level of the regulated pressure in the input passage proportional to the degree of rotation of the rotatable valve element.