Abstract: A grain-cleaning machine for obtaining grains has a desired size which is greater than a lower value and less than or equal to an upper value. The grain-cleaning machine comprises an arrangement of sieves. The arrangement of sieves comprises at least two main sieve levels positioned overlapping each other. Each main sieve level comprises a respective fine sieve followed by a respective grain sieve. At least one lower sieve level comprises a respective lower grain sieve. The at least one lower sieve level being positioned below the main sieve levels. Each fine sieve has a first mesh provided with openings having an opening size which is equal to said lower value, and each grain sieve and each lower grain sieve have a second mesh provided with openings having an opening size which is equal to said upper value.

Abstract: The invention proposes a grain-cleaning machine (10) comprising an envelope (12) with an inlet opening (13), an arrangement of sieves inside the envelope (12) and a vibration system designed to cause the sieve arrangement to oscillate. The sieve arrangement comprises at least two main sieve levels (14a, 14b, 14c) arranged the one above the other, with an inclination relative to the horizontal from a high side (L1) to a low side (L2), each main sieve level (14a, 14b, 14c) comprising respective fine sieves (141) followed by respective grain sieves (142), and under each fine sieve (141) respective fine-carrying channels (143) are arranged in communication with at least one outlet (18) for residues smaller than the grains, whereas under each grain sieve (142) respective grain-carrying channels (144) are arranged in communication with at least one grain outlet (19).