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The technology of flax harvesting depends on input impacts, including: flax harvester qualitative characteristics; working body parameters; indicators of working conditions; intervening variables reflecting the dynamic properties of the working bodies and the dynamics of the flax flow input. (Research purpose) To establish patterns and the degree of correlation between the qualitative operation indicators (pulling and deseeding quality, flax line stretching); design parameters; machine dynamic properties and harvesting conditions (height and density of flax stem, field surface, thickness and unevenness of flax straw, etc.). (Materials and methods) Based on system analysis, mathematical models of the technological process of flax harvesting were developed. Information models were introduced for examining the main flax harvesters. (Results and discussion) The paper shows that the most typical indicators of the flax harvester working conditions are the flax stem height l(t), centimeters; the seed pod area a(t), centimeters; and field surface roughness z(t), centimeters. It is found that the quality of operation is determined by the deseeding quality, percentages; the flax straw stretching, times; the location of its apical and root parts, centimeters. The estimated indicators are as follows: the pulling height h(t), centimeters, the vibrations of the combine in the longitudinal-vertical plane Q(t), degrees, the location of the apical part of the flax flaw in front of the stripper. (Conclusions) A hydraulic device was developed to adjust the pulling height from 10 to 40 centimeters, depending on the flax stem. An important reserve for increasing the deseeding quality is the change in the width of the deseeding zone of the Vk harvester, centimeters. For this purpose, a mechanism was created for moving the deseeder against the clamping conveyor, depending on the flax stem height l(t), centimeters.

When harvesting flax, its stems get into contact with the working elements of flax harvesting machines. The authors have found that the diversity of materials used to manufacture the working elements made it necessary to calculate the friction coefficients in the interaction between the stems and these materials, since it is not always possible to do this experimentally. They confirmed the possibility of calculating the friction coefficients in the butt, middle and apical parts of the stem. Research purpose Calculation of the friction coefficients of flax stems according to the given microgeometry characteristics of their surface.Materials and methods The studies were carried out on a standard device, a profile meter-and-recorder made by the Kalibr plant, make 201. Common (fibre) flax of the Mogilevskiy 2 variety at the stage of brown ripeness, at a humidity - 43.79 percent, with total length of stems – 78, 9 cm and a flax straw yield of 3.575 tons per hectare were chosen for the experiments. The flax crop was harvested by hand on the experimental field during the harvesting period. During the preparation of experimental samples, the flax stem was divided into three parts - butt, middle and apical. Each of the stem parts was divided into two halves along the axis, then one of the halves was unrolled and pasted on a solid base (steel plate). Profile diagrams of flax stems parts of were processed with conventional methods.Results and discussion The authors have obtained the friction coefficients of the stems of different humidity as they moved along the steel surface. It has been established that the calculated values of the friction coefficients are slightly higher than those obtained as a result of experiments. (Conclusions) It has been established that as the humidity of flax stems increases, the molecular component of the friction coefficient increases too. It has been determined that when the moisture content of the stems is 20-45 percent, the friction coefficient values range from 0.38 to 0.98 percent.

The quality of flax products depends on the way of flax straw retting. Currently, the best and most widely used method of flax straw retting is way of dew retting. Flax stems are laid in a thin layer on the flax field where they were grown or on a clover or grass field. During the retting process, plants tend to grow through the flax swaths depending on the air temperature (starting from 18°C) and humidity (50­-60%). Therefore, the flax straw picking up process should be done with certain efforts, however, without damaging the stems. (Research purpose) To determine the bonding forces of the flax straw with the rettery (a flax field or a grass field). (Materials and methods) The authors have designed an instrument to measure and register the considered forces as well as a general mechanism of the flax straw picking up process, which operates in conjunction with the IP 264 (BS) measurement information system, and also developed a research methodology. This system is integrated with to a laptop with the pre-­installed «Testing» software. The system is adopted to use the MS Excel software to transfer data in MS Excel format for further plotting. (Results and discussion) It has been shown that the bonding forces of flax stems, their changing pattern, and the maximum value during the picking up process depend on the degree of penetration by grass plants into flax swaths and the grass plant density per square meter. (Conclusions) In process of picking up the grass-­penetrated swaths, they show weak strength characteristics for transportation and an increased tendency to break the continuity of their picking up. The values of the ratio of the translational speed of a pick-­up device and the rotary speed of a picking device fingertip can be greater than the value of the relative elongation at the point of pulling the swath away from the ground. The coefficient of strength to pick up the swaths from a clover rettery is higher than that of flax and grass retteries.

Weather conditions in flax cultivation areas during harvesting time can be characterized with high rainfalls, relative humidity and, in some areas, extremely low temperature. Clogging of fields with stones, grass germination through flax swaths, often an absence of homogeneity on length and thickness of straw in swaths require working out new devices for straw lifting. Existing devices for picking up do not provide a high-quality lifting of flax swaths and have a low coefficient of reliability of the process. Researches and experimental-design works were carried out to create a constructive-technological scheme of the picking up device of cylindrical type with spring-loaded rigid pins. The mathematical model of the device operation when a pin touching an obstacle. The condition of balance of the mechanism under which the pin of a cilinder will operate technological process of picking up of retted flax straw without action of the safety device (spring) was described. The offered method of calculation of operation of this device was introduced in a common flax swath lifter-turners