Patent ID: 7669392

Claim:
A control system for a header of a work machine, comprising: a header support apparatus connecting a header to a frame of a work machine, the apparatus including first and second control cylinders disposed in supporting relation to opposite first and second end portions of the header, respectively, the control cylinders being controllably variable in length for supporting the first and second end portions of the header at selectable heights relative to the frame, respectively; a flow divider and control valve arrangement disposed in fluid paths in connection with the first and second control cylinders, including a flow divider configured and operable for allowing fluid flow in a predetermined manner to the control cylinders, a first control valve disposed in a fluid path in connection with both of the first and second control cylinders, and a second control valve disposed in a fluid path between the flow divider and one of the control cylinders; the control valves being operable in a first mode wherein the first control valve is closed and the second control valve is open, to allow fluid flow to and from the control cylinders in the predetermined manner; the control valves being operable in a second mode wherein the first and the second control valves are open, to allow free fluid flow between the control cylinders; and the control valves being operable in a third mode wherein both the first control valve and the second control valve are closed, to prevent fluid flow to and from the cylinders; a control system in connection with the control valves and automatically operable for controlling the first and the second control valves in the first mode, the second mode, and in the third mode, respectively, the control system configured to place the valves in the second mode both when at least one of the cylinders is fully extended or when at least one of the cylinders is fully retracted, a second control valve arrangement having third, fourth and fifth control valves, the third control valve disposed in a fluid path between a pump and the fourth and fifth control valves, the fourth and fifth control valves disposed in parallel fluid paths such that the fourth control valve is between the third control valve and the first control valve arrangement; and the fifth control valve is between the third control valve and the first cylinder.