Abstract: The chassis provides a hollow vertical frame connected to a floating extraction unit and two platforms which are formed by several panels transversally aligned to each side of an unloading pipe, which feeds a folding unloading tube. Between the extraction unit and the vertical frame, it is provided a spring unit and a hydraulic cylinder, both modifiers of the height. The extraction unit is formed by a central worm and two lateral worms, hydraulically adjustable in height, and two sweeping units. Each sweeping unit is connected to a plate over which there is supply for deviating the grain. Under it, there are settled the pipes of the hydraulic circuit, a scrapper of the inner wall of the silo-bag connected to the front edge of such plate, shaped as a flexible laminar body. Furthermore, it has an box bearing at least one floating brush, which bristles exceed the lower edge of the plate and they are in permanent contact with the ground of the silo-bag.