## Study of the oscillation processes of a front-mounted haulm harvester when it moves on the inequalities of the ground surface

In the article the calculated mathematical model of oscillations of the haulm-harvesting machine frontally attached to a wheeled tractor is constructed. A nonlinear differential equation is obtained, which describes the oscillations of a haulm-harvesting machine in the longitudinal-vertical plane during the movement of its pneumatic copying wheels along the unevenness of the soil surface. On the basis of the received theoretical results rational constructive and kinematic parameters of the front-mounted hoisting machine which provide decrease in amplitude of the specified fluctuations are defined. So, at translational speed of movement of the haulm-harvesting unit V = 3.0 m∙s–1, the amplitude of oscillations of the rotor of the haulm harvester decreases in 1.2…1.5 times in comparison with height of roughnesses of a surface of the field o h = ± 0.04 m. At the amplitude of oscillations of the lower ends of the knives of the rotary cutting device up to 4 cm, the loss of the tip does not increase significantly. However, when increasing the values of the amplitude of these oscillations to 7 cm or more, the loss of the branch increases significantly and the maximum values of which exceed 12%.

## Mathematical model of root head cleaning machine with vertical drive shaft

The operation of the machine attached to the back of the tractor to clean the heads of root crops from residues in the case of using copying pneumatic wheels causes oscillations of the tops harvester in the vertical plane, which significantly affects the quality of the process. Accordingly, the movement of the horizontal working body will depend on many structural and kinematic factors. Therefore, the development of a mathematical model that will describe the movement of the working body of such a unit is an important task. To solve which the method of construction of calculated mathematical models of functioning of agricultural machines and machine units, on the basis of theoretical mechanics and higher mathematics was used in the work.. Using which the equivalent scheme of movement of the unit is developed and the system of two nonlinear differential equations for detailed research of oscillations of the cleaner of heads of root crops in the longitudinalvertical plane at movement of its pneumatic copying wheels on roughnesses of a surface of soil is received. The mathematical model of movement of the cleaner with a horizontal cleaning shaft developed on the basis of initial equations of dynamics in the form of Lagrange of the 2nd kind allowed to establish depedencies between constructive and kinematic parameters of the car and its oscillatory characteristics. The found dependences created preconditions for the further mathematical modeling of parameters of the rear-mounted cleaner of heads of root crops, with a horizontal clearing shaft. Using the developed calculation model it is possible to optimize the values of angle B and coordinates у that characterize the oscillations of the machine in the longitudinal-vertical plane.

## Justification of kinematic parameters of coupling for wide-span row-crop unit

Effective use of the KhTZ-160 tractor is possible, with the specified width, combining the implementation of the main technological process with an additional, i.e. sowing with cultivation. Shows the results of calculations of the transverse displacements of the working bodies as a function of their placement along the width of unit and along its length relative to the transverse geometric axis that passes through the kinematic the center of the tractor without taking into account the curvature of the trajectory of tractor and possible changes in the position of kinematic center along the unit. The largest values of the transverse displacements of the working bodies, which are placed at a distance of 2.6 m, i.e. at the machine which is attached to the rear hinged system of the tractor, reach 14.5 cm at maximum angles of rotation of the unit (3 degrees). The smallest transverse movements of the working bodies are observed when placed on a geometric axis that passes through the axis of the rear wheels (less than 1 cm). The lateral movements of working bodies of 18-row wide-coverage row-crop unit depending on the tractor turning angle and their placement in the unit are considered. Kinematic parameters and coupling scheme are recommended.

## Determining the optimal working modes of working combined machines in tea plantations using the theory of similarity and dimension

The article describes the combined aggregate that we use in the tea-growing sector, developed on the base T-16 МГЧ, on the basis of the obtained patent GE P 2016 6491 B. The theory of similarity and dimension has been used, functional connection between the optimization parameters and the acting factors is determined and the regressive equation which is the basis the optimal working modes are selected.

## THEORETICAL STUDY TO DETERMINE THE STANDARD SIZE RANGE OF AGRICULTURAL TRACTORS

Since the tractor is the main energy source in agriculture, the state with highly developed agrarian production, tractor and agricultural machine building should have a fairly clear and consistent policy in the field of organizing the production and supply to agricultural producers of a wide range of tractors for various purposes. Such a policy is based on the type of mobile energy resources, i.e. tractors, based on a deep analysis and study of the volume of agricultural production, the needs for mechanized technologies, the theory of the operation of agricultural machines, the overall assessment of the development of high-tech agriculture. The purpose of this study is to develop theoretical bases for calculating the type of agricultural tractors based on an optimization of technical and economic analysis, taking into account the need for a qualitative and timely implementation of the entire closed set of works in agricultural production. During the research methods of machine use in agriculture, higher mathematics, economics, compilation of programs and numerical calculations on PC were used. The results of the study showed that the classification of tractors should be carried out not according to traction power (as is done in most countries of the world), but by the nominal traction force developed by them. It has been established that this gives a more accurate representation of the operational properties of an energy tool, which in turn allows for the very accurate and correct selection of complexes of appropriate agricultural machinery and implements for its effective operation. The presented theoretical approaches allow to determine with a high degree of accuracy the type of agricultural tractors for any country.

• ## THEORY FOR ATTACHMENT OF TRACTOR-DRIVEN SUGAR BEET HARVESTING MACHINES

An analytical study is related to giving proof and selection of the optimal parameters for the units, consisting of a tractor and a tractor-driven sugar beet harvesting machine. A mathematical model is built on the basis of this study and describes the conditions for effective attachment and give opportunity for determination of the working speed and productivity. The calculations allow finding the optimal parameters of the mentioned above aggregates in relation to productivity and energy consumption.

• ## ИССЛЕДОВАНИЕ УПРАВЛЯЕМОСТИ ДВИЖЕНИЯ МАШИННО-ТРАКТОРНОГО АГРЕГАТА

Если оценивать условия равновесия МТА в продольно-вертикальной плоскости без учета параметров α, β и δ, то теоретически условие λd ≥ 0,2 может быть достигнуто. Но в реальных условиях эксплуатации при наличии углов α, β и δ это условие может оказаться невыполнимым, в результате чего тот или иной МТА будет неуправляемым.

Расчетами установлено, что при непрямолинейном перемещении МТА по пути, наклоненному к горизонту на 12o, будет управляем только тогда, когда угол поворота управляемых колес трактора не превысит 9o. За пределами диапазона β = 0…9o устойчивость движения агрегата не удается повысить даже балластированием переднего моста энергетического средства.

При рабочем движении пахотного агрегата по наклонному участку его управляемость сохраняется, если угол поворота управляемых колес трактора не превышает 11o.

• ## THE EFFECTIVE USE OF AGRICULTURAL TRACTORS IN TURKEY: AN EXAMPLE OF ESKISEHIR

The survey forms that were prepared have been filled by 122 farmers who were tractor owners and have been analyzed. The farms were evaluated in two groups; the means are determined for Group I farms (1-259da), Group II farms (260da&greater). The most preferred usage model of multi-farm use of machinery was collectivization with neighbors. The busiest months for tractor using were April, October and September. According to different modellings, it was found that 1 tractor could be used in common by 4 farms in April in which the tractors was being used more intensely in Group I farms. It was determined that, according to the general opinions of the local farmers, “Machine Rings” was appropriate for the circumstances of Eskisehir. As it was determined that 1 tractor could not be used in common by even 2 farms in April, it was considered that it might be suitable to have tractors belong themselves when the land size was taken into account in Group II farms. When compared ownership with rental in terms of costs, having a tractor generally seems advantageous.

• ## MECHANIZATION OF OIL ROSE GROWING – STATE, PROBLEMS, PERSPECTIVES

Oil rose production is a traditional branch in the economy of the Republic of Bulgaria and in production of rose oil the country is a world leader more than a century.

In the article the evolution and state of equipment used in oil rose growing are analyzed, the problems in the mechanization of technological operations are identified and the proposals are made for a mechanization of the only one fully rely on manual labor activity – the harvesting of rose petals.

• ## МЕТОДИКА ЗА ОЦЕНКА НА ОФЕРТИ ЗА ТРАКТОРИ И САМОХОДНА ЗЕМЕДЕЛСКА ТЕХНИКА

Разгледани са предвидените в законовата уредба критерии за оценка на оферти по Закона за обществените поръчки и са анализирани предимствата и нодостатъците им при провеждане на процедури за закупуване на трактори и самоходна земеделска техника. Разработена е методика за комплексна оценка на офертите по критерия – икономически най-изгодна оферта, базирана на обективни технически и икономически критерии. Така определената комплексна оценка позволява в максимална степен да се отчете влиянието на всеки компонент в нея при запазване на предварително определената му тежест.

• ## DYNAMIC LOADS OF WHOLE OPERATOR’S BODY ORIGINATING FROM THE WORK OF TRACTOR MOWER SET

Many people are exposed to whole-body vibration (WBV) in their occupational lives especially drivers of vehicles such as tractor and trucks. The vibration-induced injuries or disorders in a substructure of human system are primarily associated with the vibration power absorption distributed in that substructure. Absorbed power is defined as the power dissipated in a mechanical system as a result of an applied force. The article presents the results of dynamic load analysis of the tractor mower set. The amount of absorbed power by the tractor’s operator, based on physical models have been calcu- lated, as a function of operating speed of tractor mower set.

• ## OPTIMIZATION OF A SYSTEM FOR DRAFT-POSITIONAL CONTROL OF MOUNTED AGRICULTURAL IMPLEMENT

The three-point linkage of Bulgarian middle power wheeled tractors "Bolgar" is equipped with a control system that allows only draft or positional control of mounted implement, which limits the effective use of tractors in the agricultural production.

The article presents results of a study on optimization of the parameters of a control system that provides mixed adjustment. Different variants of new develop lever mechanism which sums the control signals for draft and positional adjustment were analyzed and the most appropriate for practical realization was chosen. Experimental verification was carried out in field conditions, which confirmed the improved functional properties of the optimized design solution and appropriateness for implementation in agricultural practice