Attitude control for a harvester pickup

Abstract

An automatic attitude control system is disclosed for a harvester having a crop pickup connected for pivoting about a transverse axis near the forward end of a crop-gathering head. The system automatically raises or lowers the crop-gathering head to maintain the angle between the upper run of the pickup belt or conveyor and the head within preselected angular limits to assure proper feeding of the crop from the pickup to a transverse auger or the like on the head. Two sensors are provided, each with a plurality of reed switches, including a group of parallel 'raise' switches and a group of parallel 'lower' switches, and a magnetic actuator mounted for relative movement with respect to the switches as the pickup pivots with respect to the head. The sensor switches are connected to a circuit for activating a control valve for the head cylinders to raise the head when one or more of the switches in either of the 'raise' groups are closed by the actuator. The control valve is actuated to lower the head when at least one of the switches in each of the 'lower' groups is closed. A magnetic shorting bar is positioned between the 'raise' and 'lower' groups to prevent actuation of any of the switches by the magnetic actuator when the angle between the head and the pickup is within the preselected limits.