Abstract. The modern stage of development of agrarian production is characterized as a transition period in market relations. In turn market relations are characterized by crisis situations, especially at the beginning of formation of structure of economic activity of enterprises of agro-industrial complex. Increase of efficiency of tractors is directly connected with estimation of their condition and development of measures on maintenance of performance of agricultural works without refusal of tractor units, and also substantiation of volume of works of the planned period, providing working State of the equipment. Technical condition and techno-economic indicators of machines in the process of operation are constantly changing. These changes are caused by constant increase of wear of machine parts, violation of dimension circuits and conditions of contact in part mates. As a result, the technique goes from working state to non-working, which is accompanied by the emergence of tractor failures of various groups of complexity. The challenge is to prevent these failures. For this purpose the technique of estimation of a condition of tractors which consists in determination of level of ability to perform works is developed. The level of ability of the tractor to perform the work-the degree of compliance of the tractor status parameters with nominal values. Experimental researches on definition of dependences of level of ability of the tractor to performance of works and indicators of their reliability on the basis of which are received permissible and limit values of levels for the basic kinds of agricultural works.
Topicality of the research: the value of the research is caused by the need to optimize main parameters of an agricultural tractor during its operation, taking into account their influence on the crop and the actual absence of such optimization methods. Purpose of the study: the purpose of the work is to develop an energybased mathematical model of a tractor-implement unit (later-'unit') to identify the optimal parameters of the tractor, the width of the implement and the speed of the unit, which increase the efficiency in terms of energy costs. Research methods: the main research method is mathematical modeling based on system analysis, field experiments and computational simulations. Results of the research: the paper describes the proposed structure of the system under study, a justified criterion for optimizing the tractor parameters, and some interdependencies of the proposed energy-based mathematical model parameters. As a result of use of the theory of similarity and the organization of six-factorial experiment, dependence of the maximum pressure of a wheel of the tractor on the soil is received. It is revealed that with increase in the wheel size, the width of its profile decreases in a vertical load on the wheel, the maximum pressure of the wheel on the soil decreases. It is found that in the structure of total energy costs the major part is accounted for by the energy of the crop lost due to the impact of machinery and the optimality of the unit parameters (from 40 to 80 % depending on the type of operation, equipment used, operating conditions of units). Value: the proposed method of optimization of the main parameters of the tractor and unit will be useful in justifying the mass of the tractor and the power of its engine, both at the design stage of tractors and operations. The practical use of the research results benefits in a reduction of the total energy costs. The magnitude of reducing energy costs depends on the used tractors, agricultural machines and the conditions of their operation.
Intensification of work processes of agricultural machinery is a part of important national economic problems of increase of agricultural production. One way to increase intensity is to reduce grain loss when working with combine harvesters on slopes of fields. In the lateral pitch of the harvester there is redistribution of the grain heap on the screen width and cleaning sieves. The diagram of linear distribution density of the grain heap on the screen width and cleaning sieves is transformed from a uniform type of rectangle to irregular: the type of triangle, trapeze without a shift or with a shift in the direction of the pitch. We have large losses of grain, because of the uneven linear distribution density of the grain heap on the screen width and sieves. The article offers various methods and devices, which have certain advantages and disadvantages, to reduce grain loss. One of the promising directions to reduce grain loss is the dynamic method, which uses a specific device as a set of hinged-lever units. However, one of the major drawbacks of these devices is the equality of oscillation frequency of the longitudinal and lateral pitch. The adopted working hypothesis and studies of the process kinematics and dynamics will define the main structural and technological parameters of the cam mechanism to align the linear distribution density of the grain heap on the screen width and sieves.
The article presents the technology of hardening the fingers of the reapers of combine harvesters by electrospark processing. To strengthen the cutting surfaces of the fingers, it is recommended to use an amorphous alloy grade 84KXSR. The operational tests presented in the work showed that wear and dulling of both serial products and experimental parts with electric spark coatings is characterized by two stages: running-in and natural wear. The running-in occurs during the running time of the fingers in 1 ha. The results of operational tests showed that the application of a wear-resistant electrospark coating of amorphous alloy grade 84KXSR with a thickness of 30 μm and a track width of 2 mm on the cutting surfaces of the fingers of the headers of grain harvesters makes it possible to increase the resource from 1.4 to 2 times.
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