The improvement of grain-cleaning machines is based on the principle of air purification and occurs in one direction - the creation of swirling air stream. Conical separator with swirling air flow divides grain material into two fractions: light and heavy. The quality of its division into fractions in many respects depends on the way of supply of initial grain material on separator cone. In initial option the supply of grain from the bunker located above was carried out by the stream on the cone of dissector, and from there - on working cone of the separator. Therefore the bunker distortion concerning the vertical involves the unevenness of ring supply of grain, and, as a result, unsatisfactory quality of grain purification. The way of modernization of dissector which has been offered will allow reducing the unevenness of ring supply of grain that, in turn, will increase overall performance of the separator. For pilot studies the dissector having the dividers which are on the cone has been designed and made. They promote uniform division of grain material already at initial stages of its exit from the bunker. While the investigation of work of feeder batcher it became clear that on the supply of grain material within 20-60 kg/h the quality of its work was considered satis-factory, when giving 80 kg/h and the quality of work sharply fell. By the results of the experiments on the purification of grain made on the separator it was possible to draw the con-clusion that the completeness of division of grain material when giving on experimental dissector-distributor was 10 % higher than in comparison with overall performance on an initial dissector of basic model. The losses of the main culture decreased on average by 15-25 % in comparison with the separator having the initial bunker batcher in the design.