In this study, a novel rotary cleaning device was used for the separation and cleaning of wheat grains. This research analyzed the influence of the inclination angle of the sieve drum (K) of the device on the quality of these processes. In this article, the results obtained for four selected rotational speeds (n(b)) of the sieve drum are presented. The quality of the separation and cleaning of the wheat grains was evaluated using three cleaning process parameters: coefficient of plump grain mass separation (W-z), coefficient of fine impurities separation (W-d), and total coefficient of cleaning effectiveness (E). Based on statistical analysis of the results, the inclination angle of the sieve drum had a significant effect on the quality of the wheat grain separation process. Coefficient Wz was highest for sieve drum inclination angles of K = 0 degrees and K = 2.5 degrees, whereas Wd was highest for K = -2.5 degrees. The total coefficient of cleaning effectiveness (E) was characterized by different values for different inclination angles of the sieve drum.