## THE STUDY OF MOVEMENT WIDE SPAN TRACTOR (VEHICLES) WITH KINEMATIC (TURN OF WHEELS) METHOD OF ITS CONTROL

Prospective energy technology devises for controlled traffic farming is the wide span tractor (vehicles). Their driving can be built behind the kinematic or force principle of the turn. At the kinematic turn, the schemes are applied by turning the steered wheels (front, rear or both front and rear) relative to the car’s frame. The widest distribution in wide span tractor (vehicles) was obtained by turning schemes with all steerable wheels. The theoretical foundations of the dynamics of the parallel-span parallel motion tractor (vehicles) in the horizontal plane are presented in the article under the kinematic method of its control (by turning the wheels). Theoretical research is based on the basic principles of theoretical mechanics, tractor theory, statistical dynamics and the theory of automatic control of linear dynamical systems when they reproduce statistically random control and disturbing input effects. The amplitude and phase frequency characteristics are based on the analysis of the evaluation of the degree of influence of the circuit and parameters of the investigated wide span tractor (vehicles) on its controllability and stability of motion. The physical object of the theortical studies was the prototype of the wide span tractor (vehicles) of the new design. Mathematical models of the wide span tractor (vehicles) movement are represented in the differential and operator form of recording. On the basis of mathematical models, the calculated amplitude and phase-frequency characteristics of the dynamic control system development are plotted, represented by the average rotation angle of the front wheels of the wide span tractor (vehicles). The constructed mathematical models, amplitude and phase-frequency characteristics allow estimating the effect of the control parameter of the wide span tractor (vehicles), as well as its design and other parameters on the controllability and stability of motion.

## 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.

• ## DEVELOPMENT OF STRUCTURES AND RESULTS OF EXPERIMENTAL STUDIES OF THE NEW MODULAR POWER UNIT

The article presents the results of experimental studies of the soil tillage unit based on a new modular power machine of variable traction class. It includes the universal tractor of drawbar category 1.4 (2.0) and technological unit as an additional bridge, having active drive wheels from synchronous PTO-shaft of the tractor. The new modular power facility with experienced five-part plow has been investigated in wheat stubble plowing. Obtained operational and technological parameters are compared with the same regulatory parameters of the tillage unit as part of a tractor of class 1,4 and a three-part plow. It is found that the performance of a new replaceable unit is 1.9 times higher and the specific fuel consumption is 27.5% less in comparison with the standard unit.
Special laboratory and field experimental studies established the degree of influence of the wheels on the process of compaction of different initial moisture content (12.8…20.8%) after the passage of the wheels of the front and rear axles of the tractor of class 1,4.

• ## THEORETICAL PREMISES FOR ENHANCEMENT OF EFFICIENCY IN THE USE OF REVERSIBLE PLOUGHS

Theoretical analysis has been undertaken to determine the effect of the plough’s structural layout on the total length of the tractor- implement unit’s turning path. Basing on the results of the analysis, the utility of employing a reversible plough instead of a conventional one has been assessed. Eventually, it has been found that, when ploughing a 68.2 m wide land with an area of 8.2 hectares, the total length of the path of travel on the headlands is 1980 m for the reversible plough unit and 2035 m for the conventional plough unit, which is an increase by 2.7%. At an average manoeuvring speed of 1.75 m/s (6.3 km/h), the total amount of time spent for turning by a unit with conventional ploughing tools will be greater by mere 0.5 min. If the ploughed land is magnified by almost 1.5 times (12.0 hectares instead of 8.2), the width of the field will reach 100 m. In this case, the ploughing unit with a conventional plough will travel an 850 m longer path on the headlands. At the above-mentioned average headland manoeuvring speed of 1.75 m/s the increase of time spent by this type of tilling unit for turning will amount to just 8 min. The only advantage of the reversible plough over the conventional one is the opportunity to avoid the appearance of crown ridges and dead furrows when tilling the field. Meanwhile, it is to be noted that with a sufficient qualification of the machine operator the said advantage of the newer tilling implements can be levelled down. Considering the equal productivity of the compared tilling units, a negligible difference between their rates of non-productive expenditure of working time as well as taking into account the infrequent performance of ploughing, i.e. once in several years, in view of the considerably (several times) higher cost of a reversible plough, the acquisition of the latter presents an economically inadvisable option.