The authors showed that the cotton-textile cluster efficiency (the capacity of the machine-tractor fleet, cotton yield, the production profitability) largely depended on the use of the optimal number of tractors and agricultural machines. The existing methods (theoretical, graphic, economic and mathematical) were difficult for practical use and did not take into account the specifics of mechanized cotton growing processes. Therefore, it was important to develop a simple normative method for determining the optimal composition of the machine and tractor fleet for clusters, corresponding to the technological map for the production of raw cotton. (Research purpose) To calculate the required amount of agricultural machinery based on the established standards. (Materials and methods) The authors developed an algorithm for determining the standard coefficients of the equipment necessity per 1000 hectares of arable land. These coefficients for each type of equipment were established in the context of technological operations of growing cotton: plowing, soil preparing for sowing, sowing seeds, cultivating the soil between cotton rows, mechanized removal of growth points of the main stems and side branches of plants, defoliation with chemicals, machine harvesting and transportation of harvested cotton – raw. (Results and discussion) The authors proposed the term “model cotton-textile cluster”. They calculated the required amount of equipment for such a cluster with an area of 13,732 hectares. They determined the percentage of the machine and tractor fleet: the share of tractors – 28 percent, cultivators – 22, trailers – 19.8, cotton pickers – 13.8, the rest – 16.4 percent. They emphasized that the machines fleet could expand with the arrival of new modern machines produced by machine-building plants of the republic and imported from foreign countries. (Conclusions) The authors accepted the machine and tractor fleet of the cotton-textile cluster with the number of equipment 1660 units as rational. They proved that it ensured the implementation of all technological operations within agrotechnical terms.

The main quality indicators of tractor trains (the number of trailers and their total load capacity, speed and stability of movement, braking distance, etc.) depends largely on the correct choice of the type of a base tractor. The existing methodological principles for optimizing the dimension range of agricultural tractors do not take into account the type of trailers. Therefore, the task of a rational choice of the base tractor type, taking into account the most complete utilization of the capacity of existing trailers and engine power, has become rather relevant. (Research purpose) Selection of a tractor model for hitching a group of 2PTS-4-793-03A two-axle trailers according to the criteria for carrying capacity and energy consumption of a tractor train. (Materials and methods) The authors have studied mass, weight and velocity parameters of the 2PTS-4-793-03A two-axle trailers, as well as the parameters characterizing the mechanical capabilities of the studied tractor. The studies employed the methods of implement mounting on machine-tractor units and elements of the theory of a tractor. (Results and discussion) The authors off er an algorithm of solving a problem of choosing a tractor. As a results, the ТТZ 60.10 tractor with a wheel formula of 4К2 available at farm enterprises and included in machine-and-tractor fl eets and clusters has been selected as a power base of a tractor train. The authors have determined the number of trailers, which equals four, the tractor train speed ranges of 4-28 kilometers per hour, the tractor engine power amounting to 8.5-59.5 kilowatts, changes in critical values of the eff ective engine power corresponding to 13.492-94.444 kilowatts, as well as specifi ed some other criteria. (Conclusions) The ТТZ 60.10 tractor with a wheel formula 4К2 and 46.7 kilowatt of eff ective engine capacity has been considered the optimal choice. It has been proved that this tractor can move four 2PTS-4-793-03A two-axle trailers with a total weight of 15,600 kilograms along asphalt-concrete roads with a rational speed of 9.505 kilometers per hour. The rationality of choice has been proved by calculating energy saving criteria: full traction effi ciency accounts for 60 percent, engine load factor is 89 percent, and traction power utilization amounts to 96 percent.

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The authors showed that the multichannel system state graph of modern tractors, combines and agricultural machinery in Uzbekistan, by the nature of its functioning, was a kind of mass service system. They confirmed that this circumstance was not taken into account when studying the existing system of corporate technical service. They pointed out the relevance of determining the influence of the branded technical service system parameters on its condition using the methods of the mass service theory. (Research purpose) To evaluate the state parameters of a proprietary technical service multichannel system according to the results of the timing of combine harvesters maintenance. (Materials and methods) The authors studied the multi-channel system state graph of a proprietary technical service without a queue. The system included 109 Case-2166 combine harvesters and 7 car-mobile workshops. They used the methods of mass service theory. (Results and discussion) The authors established a linear relationship between the number of occupied car-mobile workshops and the average value of the service time at a constant intensity of requirements. It was revealed that it took 3.33 hours to fix one malfunction of one combine, that is, one workshop would be occupied. If 3.24 demands were received in the service center in one hour, then all 7 auto-moving workshops would be occupied. (Conclusions) The authors revealed that for a single-channel proprietary technical service system the average value of the time for eliminating one malfunction of one combine should not exceed 3.33 hours. They calculated the parameters at which all channels (7 workshops) will be occupied in the 7-channel system of corporate technical service: 3.24 requirements arose in one hour, on average, each workshop took 2.16 hours to fix one malfunction.

The use of small-scale machinery proves to be common for agricultural, transportation and other types of work on small-scale farms, peasant farms, family gardens, farmsteads, on hilly lands and inconvenient areas, where the use of traditional powerful machinery is impossible or economically impractical. Small-scale machinery as well as powerful agricultural machinery rarely passes state tests. One of the main reasons for that is a lack of indicator systems for agrotechnical, operational and technological, reliability, economic and ergonomic assessment. The necessity of determining such systems (sets, criteria, indicators) is argued to be important. (Research purpose) The research aims to identify performance assessment indicators for agricultural small-scale machinery by capitalizing on the existing indicators for powerful machines and hands-on experience of exploiting mini-machinery in small farms of Uzbekistan. (Materials and methods) The primary materials are the performance indicators for the agricultural machinery, provided by the existing state and industry standards. The study uses the methods of system analysis, logical thinking, monographic observation and set theory. (Results and discussion) As a result of ranking, several performance indicator systems were selected for the agrotechnical, operational-technological, reliability, economic and ergonomic assessment of small-scale machinery. (Conclusions) It was found out that for the general assessment of the structure parameters, the quality of the technological process and the functionality of small-scale machinery prototypes, it is reasonable to use 26 main and 14 auxiliary indicators. At the same time, a reduction in material and labor resources is expected in the process of testing.