in an agricultural combine , a header float system using a floating header having a frame , a support member supporting the frame from the ground , and a suspension variably supporting the frame from the combine . the suspension comprises a sub - frame removable attaching to the combine , links movably attaching the frame and the sub - frame , and one or more float cylinders moveably supporting the frame from the sub - frame . a float circuit connects to the float cylinder , and a float valve connects the float circuit to a main hydraulic circuit . a pressure sensor connects to the float circuit , and a controller communicates with the float valve and the pressure sensor . the controller maintains pressure in the float circuit at a target value by continuously reading the pressure sensor and commanding the float valve to add or subtract hydraulic fluid in the float circuit until pressure equals the target value .