US Patent 10231381 Pneumatic grain level sensor and method therefore

A combine including a frame, power unit and a crop gathering and processing device. A grain tank is mounted on the frame. An elongated closed end tube is vertically oriented within the grain tank and has a plurality of uniformly spaced openings along its length. A pneumatic pump pressurizes the interior of the tube. A pressure sensor senses the interior pressure of the elongated tube, so that grain building up therein selectively covers the plurality of openings to cause a proportionate increase in air pressure.