APPARECCHIO DI PULITURA A PIU' PIANI PER MIETITREBBIA

The invention relates to a multi-plane cleaning device for combine harvesters having an upper screen and a lower screen, with the upper screen comprising a plurality of individual part screens which are arranged so as to be offset with respect to one another in different planes and between which are attached fall steps through which air flows. The essential features of the invention consist in that the individual part screens (5, 6, 7) have different lengths, the lengths of the part screens (5, 6, 7) increasing in the conveying direction (F). The individual fall steps (8, 9, 10) have different heights. The height of the fall steps (8, 9, 10) decreases in the conveying direction (F), and the distance of the fall steps (8, 9, 10) from one another increases in the conveying direction (F). The height of the fall steps (8, 9, 10) and the length of the part screens (5, 6, 7) are dependently related to each other in such a manner that as the length of the part screens (5, 6, 7) increases, the respectively assigned height of the fall steps (8, 9, 10) decreases.