Patent ID: 6588187
Filing Date: 2003-07-08
Classification: A01D,Y10S

Abstract:
A harvester having a frame adapted for forward movement over a field and including a selectively operatable row unit supported for vertical movement relative to the frame by a hydraulic lift assembly, the harvester including height control structure for controlling the lift assembly comprising:a ground sensor providing a height signal dependent on the position of the row unit relative to the surface of the ground; a first proportional valve connected to a source of hydraulic pressure on the harvester and to the lift assembly; an electronic controller connected to the first proportional valve and to the ground sensor, the controller responsive to the height signal for providing an electrical valve control signal to the first proportional valve to operate the lift assembly and maintain a preselected vertical position of the row unit relative to the ground in an automatic mode, wherein the valve control signal is dependent on the difference between the preselected vertical position and actual row unit position relative to the ground; and an electrohydraulic valve connected to the controller and the lift assembly and having an on position for providing lift assembly operation for lowering the row unit and a closed position for preventing lowering of the row unit, the electrohydraulic valve responsive to an operational signal from the controller to select the closed position of the valve and prevent the lowering of the row unit when the row unit is not operating.