The preparation of grain for feeding is one of the most important operations of feed processing. Nowadays, the most widespread way of preparation of grain for feeding is its reduction in size. At the moment the variety of reducing devices is rather wide and is characterized by the diversity of constructive solutions. The choice of the specific constructive solution for the needs of an agricultural enterprise depends on the tasks which are set by the agricultural goods producers during animal feeding. At the same time, scientifically the directions of improvement and modernization of reducing devices are of interest with the purpose of the choice of a scientific research direction. In the article the results of the review of forage grain grinders used in agricultural production are given. The main trends of construction improvement are considered, the directions of the scientific research are defined. Keywords: REDUCTION IN SIZE, GRAIN GRINDER, CONSTRUCTION, IMPROVEMENT, GRAIN SEPARATION, VIBRATION

Livestock farming, as one of the main sectors of the agro-industrial cluster, cannot do without good quality forage. For the best absorption of feed, all the nutrients that make up its composition should be given to the animals in a milled form. Hammer mills are among the most compact machines for milling. The grinding of grain forages is a rather energy-intensive process. One of the variants for solving the power intensiveness problem can be the application of a a hammer crusher with periodic fluctuations in the angular speed in the rotation of the the working body. That is accompanied by the appearance of additional external stimulating force - vibration on the elements of a hammer crusher. In the article the question of vibration occurrence at non-uniform rotation of a crusher working body drive pulleys is considered. And such parameters as vibration acceleration, vibration displacement, and vibration velocity in three different axes are considered. In order to optimise the vibration parameters, experiments were carried out on units of different designs with different centre of rotation offset (2 mm). At this uneven rotation speed of 1800 min-1, the vibration velocity on the X-axis increased by 546% and 200%, depending on the machine design. The vibration displacement on the same axis, even at 450 min−1, increased by 442%. Based on these results, we examined the prerequisites for the investigated hammer crusher drive design, which is expected to improve the separation and evacuation process of the crushed product from the crushing chamber, and have an overall positive impact on the crushing process.