The new preparation method for vitaminic grass flour from leaf part of grass plant is proposed, constructive and technological scheme of separator of small leaf part of grass plant is substantiated. As a result of theoretical researches equations of equivalent forces affecting plants’ stems in each quarter of circle of eccentric rotation are obtained, conditions for stems moving towards pitch of separator screen are determined.

To increase the production of livestock products, it is necessary to feed the animals with full-feed mixtures. The main component of the feed mixture is feed, which consists of grain feed, vitamin-grass meal (VGM) and other additives. Currently, high-temperature methods of drying hay are used for the production of VGM, which require high costs and expensive technical means. Therefore, to reduce operating costs and equipment costs, authors proposed a technology and a line for the prepa-ration of VGM from the leaf part of herbs. As part of the VGM preparation line, the main machine is a separator of the leaf portion of grass from chopped hay. The separation process is due to the fact that when grinding dry hay in sieveless shredders, the delicate leaf part is finely chopped, this con-tributes to the process of separating the leaf part of the grasses. The purpose of the research is to determine the speed of hay moving along the surface of the sieve, which allows to determine the productivity of the line by mass feed and flour. For the theoretical determination of the average speed of movement of the sieve, the method of mathematical analysis was used. To determine the actual value of the speed of movement of hay on the surface of the sieve, the method of one-factor experimental research was used. As a result of theoretical studies, the analytical expressions were obtained to determine the performance of the separator, the average speeds of the sieve in the hori-zontal direction and the movement of hay on the surface of the sieve. As a result of experimental studies, a regularity of the change in the average speed of hay movement depending on the length of the sieve was obtained, and this regularity provides an empirical expression for determining the actual value of the average speed of hay layer movement on the surface of the sieve and it is 0.19 m/s. With the average line capacity for mass feeding, the thickness of the transported layer over the sieve surface was 0.0186 m, and it is not maximal for the separator of the leaf part of grasses.

Optimal separator parameters have been obtained, as a result of experimental investigation of separation of leaf part from pre-shredded alfalfa.