The BA series rotating extractors are used for the emptying of the residual cone in the internal part of the flat bottomed silos when remaining material that could not be unloaded by means of gravity. The fixed rotating extractor permits the removal of the residual cone by conveying the material still on the sides towards the central part without any operators inside the silo. Emptying is guaranteed by the rotation of the moving arm around the axis, driven by the driving wheel positioned on the free extremity, a clutch applied to the wheel permits the movement only if the auger, has unloaded all the cereal that previously obstructed it.