In this paper, it is proposed to use a self-propelled pneumatic mini-seeder with replaceable mechanical sowing devices designed and manufactured using computer technologies, advanced software and threedimensional printing for seeds selection. As a result of the research, hightech operating devices for a grain-drill feed with screw and disk-pin continuous seed metering are designed and manufactured. Grain-drill feeds allow sowing of free-flowing and non-free-flowing seeds, when used as seed meters on self-propelled pneumatic mini-seeders for selection sowing of grass seeds. Analysis of laboratory results of and field studies of the proposed grain-drill feeds allowed to determine the qualitative indicators of their performance: at a disk rotation speed of up to 15 rpm a linear dependence of the seed supply on the rotation frequency is provided; in the field studies, the instability of bluegrass seeding did not exceed 8%. The highest performance of the screw is obtained at the angle of choke inclination of 30...35 degrees with the seeding instability indicator of 2.5...3.5%. The developed grain-drill feed will significantly reduce the range of seeders and expand the set of sown seeds of various agricultural plants with one brand of a grain-drill feed.

The sowing unit is one of the main devices of any planter, determining the quality of sowing, especially when it comes to the sowing unit of the central dosing. The article describes the proposed technological scheme of sowing of difficult seeds with a pin-disc type metering device. Its feature is the presence of an activator of seed outflow from the bunker. The proposed apparatus is capable of dispensing hard-to-sowing seeds with high quality, which include most of the seeds of cereal grasses (and not only). An original technique and a specially developed laboratory setup for assessing the longitudinal uniformity of seeding are described. The essence of the technique consists in sowing seeds on a moving horizontal platform with sectors of the same size. With its use, time and labor costs for conducting experiments are significantly reduced. The results of theoretical and experimental studies to determine the optimal design and operational parameters of the proposed device are given. Analysis of the results of the research is presented herewith.

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