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The paper considers a new technique for assessing the technical level of agricultural tractors competing in one power range. The existing methods of evaluation of technical level, both in Russia and abroad, are associated with expert approach that is limited by the qualitative nature of conclusions, which does not allow to predict quantitative change in performance. In this regard, if there are up to 35 models in the Russian market with equal power capabilities, the problem of making a choice arises. A general indicator of technical level is the ratio of the replacement capacity of the arable unit based on a tractor model under consideration to the replacement capacity of the arable unit based on a reference tractor, which are determined by computer simulation in reference conditions.

The process of interaction of the driving wheels of mobile energy resources with soil is considered. A computational and experimental method is proposed for plotting the shear stresses in the contact zone of the skid wheel with a supporting surface, based on the use of normal stresses obtained for specific ground conditions. The character of the interaction of the driving wheel of the tractor with various types of supporting base has been studied in detail: a dirt road, stubble, a field prepared for sowing. It is revealed that, contrary to the generally accepted ideas, the slipping wheel has practically no adhesion zone in the contact spot. After touching the tiller of the supporting surface, it immediately begins to shift backward.

Maximum pressure is an essential parameter determining the degree of environmental impact of pneumatic tractor wheels on soils. The authors of the paper offer a method for determining and adjusting maximum pressure of a pneumatic tractor wheels on the supporting surface. The paper contains an analysis of the variation of maximum pressure on soils for various values of internal tire pressure and vertical load on a wheel. The above method allows parameters for systems of monitoring and adjustment of maximum pressure on soils to be set up by measuring tire flexure and adjusting it through changing the internal air pressure.

A feature of the present state of the Russian agricultural industry is that productive resources (tractor pool, arable land area and number of workers involved) are diminishing and the reduction does not have a quantified value. In the prevailing conditions of limited resources, agricultural enterprises are forced to operate tractors beyond their amortization periods on a massive scale, which results in an unpredictable service life. This situation calls for an assessment of the optimal composition of the tractor pool in terms of number and age. By way of a solution to this problem, the given article presents a methodological approach as to the analysis of two opposing factors. On the one hand, it takes into account the fact that the use of tractors beyond their depreciation periods leads to increased costs of their operation and further yield losses related to the poor technical condition factor, which is proportional to the number of tractors with expired depreciation periods.