Abstract. Practical use of wide span tractors (vehicles) for controlled traffic farming needs further motivation of the principles of their automatic steering, allowing maximum reduction of area losses of the field under the engineering zone at least 1.5 times. The use of contemporary wide span tractors (vehicles) with a track width more than 7.5 m allows reaching a value of the area losses of the field under the engineering zone not more than 5…6 %, which is quite acceptable. The presented brands of such tractors are provided with various technological equipment and means of automation, the technological significance of which can be estimated only by means of objective assessment methods. The developed equation for the estimation of the potential efficiency of the wide span tractors makes it possible to conduct analysis of the degree of impact upon them made by their design parameters and indicators of technical characteristics. Estimation of the degree of potential efficiency, which the contemporary wide span tractors should have, showed that the result exceeds the potential efficiency of the conventional machine and tractor aggregates by 1.5-2 times.

In order to ensure the stable motion of the wide span tractor, the design of its linkage has to provide for its independent turning on the horizontal plane. That implies the high priority of the issue of substantiating the parameters of the wide span tractor linkage unit. The aim of the study was to improve the efficiency of operation and application of wide span tractors through the substantiation of the parameters of their linkage units. The study uses as its basis the fundamental principles of the theoretical mechanics, the theory of tractor, the statistical dynamics and the theory of automatic control of linear dynamic systems responding to statistically random controlling and perturbing input actions. Following the results of the undertaken investigations, it has been established that the most desirable setup of the wide span tractor's linkage unit in terms of the tractor's response to the controlling action (angular displacement of steering wheels) and perturbing action (angular displacement of linkage unit on the horizontal plane) is when the instantaneous centre of turn situated at the point of convergence of the centrelines of the lower draught links coincides with the tractor's centre of mass.

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At present the appearance of novel energy-saturated tractors of traction-energy concept requires not only new principles of their aggregating but also the method of assembling aggregates on their basis. Aim. To increase the effi ciency of assembling soil-processing aggregates with traction and drive working units based on energy- saturated tractors of traction-energy concept. Methods. The study involved the use of the methods of tractor theory, use of machines, fi eld experimental investigations, statistical methods of processing study results, as well as methods of composing programs and numerical computations on PC. Results. The method of assem- bling soil-processing aggregates with traction and drive working units was suggested on the basis of technical information, available for a wide audience of specialists. Conclusions. The problem of assembling soil-pro- cessing aggregates with traction and drive working units on the basis of energy-saturated tractors of tractor- energy concept should be solved with the consideration of the suggested condition of useful power via traction, determined by the friction properties of a tractor, and the power which the tractor can actually transmit via a power take-off shaft or a hydrosystem.

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The article exposes the results of the mathematical simulation of the agricultural bridge equipment functioning. The mathematical models describing the functioning of the agricultural bridge equipment were checked for adequacy by comparing the theoretical and experimental amplitude-frequency characteristics of the oscillations of its heading angle and lateral displacement. It was established by the result of investigated characteristics’ quantitative assessment that a satisfactory coincidence of the theoretical and experimental results, as well as a positive result of checking the adequacy of the mathematical models of the vertical and the horizontal oscillations of the agricultural equipment indicate a possibility of their further use for solving scientific and practical problems.

One of the topical directions in the development of agricultural tractor construction can be the formation of machine-and-tractor units according to a modular principle, using technological modules with the driving wheels. The aim of this work is to study the possibilities how to increase the operational and technological indicators of the operation of an agricultural aggregate in a modular aggregation system due to the selection of rational parameters of an elastic-dissipative connection of the energy and the technological modules. The obtained data were processed by statistical methods on a PC, using correlation and dispersion analyses. It has been established by experimental investigation that the operation of a ploughing block-modular aggregate, while ensuring rational rigidity of the connection of its energy and technological modules, is achieved by throttling the hydraulic system of its rear suspension at the level of 75%, characterised by an increase in its performance by 6% and a decrease in the specific fuel consumption by 12.4%. In addition, the level of vertical vibration load of the operator corresponds to the allowed fatigue rate for 8 h of work.