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.