EN
Soiling of the potato tubers changes their shapes and causes that the surface properties are, to a certain degree, similar to clods of soil. The above affects operation of separators. The purpose of the studies was to determine the influence of soiling of the potato tubers on the duration of the process of their separation by the separators of the combines: Z 644 and E 667/4, and on the position of the impact point of the potato tuber from the conveyor of the separator which affects uniformity of loading of sorting table. There have been constructed two laboratory stands adapted to filming which designs were based on the separators Z 644 and E 667/4. Films were taken using the Pentaflex AK 16 motion picture camera with speeds of 32 and 96 frames per socond which correspond to exposure times of 1/64 and 1/180 second, respectively. The negative films NP-55 of the speed 20 DIN have been used. The filmed object have been illuminated with four LF halogen lamps, 1000 W each. Operation time and point of the fall of tubers from the conveyor were read on the S-521 film cutting table which had been adapted for single frame analysis. The materials used for analysis were: a) tubers soiled in a natural way, b) cleaned tubers. The increase in separation time had been stated for the soiled tubers. For example, the average increase in separation time of the soiled tubers (when compared with the clean ones) was 26% in the case of Alka potatoes on the inclined separator of the Z 644 combine, and 12% in the case of Aba potatoes on the inclined separator of the E 677/4 combine. The largest amount of tubers (in per cent) falls on the 6th and 7th decimetre in the case of clean potatoes, and on 7th and 8th decimetre in the case of soiled ones. That deteriorates the conditons of uniform loading ot sorting table.