Caterpillar Inc.

Arlyn P Wilcox

Michael L Knussman

Jeffrey Michael Thate

William J Spivey

Nathan T Schenkel

Stephen T Tady

Glen P Running

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

Hydraulic system providing down force on a work implement

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. A proportional and integral controller is coupled with the first processing device to receive the fifth signal and coupled with the second processing device to receive the seventh signal.

Method and apparatus for controlling an electro-hydraulic differential

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.

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Rockford, IL, United States of America

Arlyn P Wilcox