Abstract: Row unit lift structure includes electrohydraulic proportional valves connected to an electronic controller which receives inputs from a manual raise/lower switch, a rate response potentiometer, and height control potentiometers in the cab. Signals are also received from row unit height sensing transducers, a tachometer and shaft rotation sensors. When the units are lowered and operational, the controller compares the signals from the height sensing transducers with the signals from the height control potentiometers and sends an electrical control signal to the proportional valves to maintain a selected row unit height. The magnitude of the control signal and thus the rate of correction of height are determined by the rate response potentiometer and the amount of variation between the actual and desired row unit height.

Abstract: Row unit lift structure includes electrohydraulic proportional valves connected to an electronic controller which receives inputs from a manual raise/lower switch, a rate response potentiometer, and height control potentiometers in the cab. Signals are also received from row unit height sensing transducers, a tachometer and shaft rotation sensors. When the units are lowered and operational, the controller compares the signals from the height sensing transducers with the signals from the height control potentiometers and sends an electrical control signal to the proportional valves to maintain a selected row unit height. The magnitude of the control signal and thus the rate of correction of height are determined by the rate response potentiometer and the amount of variation between the actual and desired row unit height.

Abstract: A harvester head, such as an ultra-narrow row cotton (UNRC) fingerhead, includes one or more rockshaft cylinders connected to a hydraulic circuit including first and second closed center valves connected to a shuttle valve to allow the rockshaft cylinders to be controlled by two separate height sensing shoes, one at each end of the head, which are not mechanically linked to each other. The closed center valves provide a positive displacement of oil to and from the rockshaft cylinders to control the height of the head. The shuttle valve provides head lift when either of the height sensing shoes indicates a raise condition and head lower only when both shoes indicate a lower condition. Electrohydraulic valves connect the source of hydraulic pressure on the harvester to the cylinders through the shuttle valve for operator selection of raise and automatic height control functions.