No 10 (2016)

Articles

Revival of domestic agricultural engineering is an urgent and important task of the state

Kolchin N.N.

Abstract

The United Nations Organization has called for the need to increase world food production by 70% to 2050. Russia has 9% of world agricultural land and 2% of population of the world, and could not only provide itself with the quality production, but supply the world market. However, today the state support of our agriculture and enterprises producing agricultural machinery is insufficient. One of the most important conditions of agricultural development is a large-scale revival of domestic agricultural engineering, one of the oldest industries of the country. The article presents extracts from the history of this industry, gives an overview of main features and development trends of domestic and foreign agricultural engineering. It is noted that in recent years production and development of domestic agricultural machinery has been reduced significantly. Being its key customer and consumer, the Ministry of Agriculture of the Russian Federation stopped formerly active and useful participation in the development of technical means. Import of foreign machinery increased. But the imported machines do not always sufficiently conform to our conditions. The development of domestic production of agricultural machinery and its use are to be granted the status of top-priority task of the state. A set of measures is proposed for the implementation of this task. These measures will provide the necessary level of food security of the country, the welfare of population, the growth of food exports and raising Russia’s international standing.
Tractors and Agricultural Machinery. 2016;(10):3-7
pages 3-7 views

Disk braking mechanism of a tractor produced by Minsk tractor works

Abaev A.K., Kachmazova E.K., Kachmazova E.I.

Abstract

Operation of tractors in high-mountain conditions is very different from their use in flat terrain. When braking on a steep long slope with large number of turns with minimal radius, the intensive heating of braking mechanisms is occurred, which not only reduces the efficiency of braking system, but also often leads to a complete failure. The aim of the study is to improve the operational efficiency of disk braking mechanism of a tractor produced by Minsk tractor works when braking during direct motion by means of increasing the impact of pressure disk on brake disk by the use of tractive effort torques that arise between them. The general characteristics of tractor braking mechanisms, as well as the characteristics of a proposed improved braking mechanism are given. The improved braking mechanism allows to rotate simultaneously the pressure disks in the direction of rotation of brake disks during tractor forward motion. At that, the tractive effort torques generated in the process of interaction of surfaces of pressure and friction disks match with the torques applied to the pressure disks from the side of brake gears. As a result, the total axial forces affecting from the side of pressure disks on brake disks are increased, which leads to the efficiency improvement of tractor braking. The patent no. 2435997 for the invention of disk braking mechanism has been received based on this study. The proposed design significantly improves the braking capabilities of a tractor. It can be used in the braking systems of tractors, vehicles and motorcycles.
Tractors and Agricultural Machinery. 2016;(10):8-10
pages 8-10 views

Determination of quality of cultivation by means of soil spiker

Kovalev M.M., Sheychenko V.A., Shevchuk V.V., Fadeev V.G.

Abstract

Studies are carried out with the purpose of increase of soil cultivation quality through the improvement of technological process and design of a soil spiker with variable wedge angle of needles. When rotary needle working organs influence the soil, the following processes take place: the partial soil casting back and aside, soil layer hoeing, clods crumbling, plant remains burial and their extraction from soil, weed destruction and leveling of microrelief roughness. Quality indicators of performance of soil cultivation process by means of experimental section of soil spiker are determined. Investigations of soil cultivation process by means of experimental and serial sections of soil spiker are carried out on an experimental unit. Experimental section contains a disk with needles having the wedge angle of 9 and 5 degrees. The section of universal multifunction 5.4 beet hoe is used as a serial one. The soil samples are obtained in soil layers at a depth of 0-5; 5-10 and 10-20 cm. Soil quality indicators are determined according to state standards of the Ukraine 11465-2001 «The quality of the soil. Determination of dry matter and mass humidity» and 11272-2001 «The quality of the soil. Determination of density of structure on dry weight». The experiments are conducted in three replications. Following quality indicators of soil loosening by means of soil spiker are established as results of the studies: the cutting (destruction) of weeds in treatment area is 98.5%; the content of fractions of size up to 25 mm for needles with wedge angle of 5 degrees is 88.2%, for needles with wedge angle of 7 degrees - 90.5%, for needles with wedge angle of 9 degrees - 93.5%.
Tractors and Agricultural Machinery. 2016;(10):11-13
pages 11-13 views

Determination method of rational design parameters for four-shaft not-coaxial preselector transmissions of agricultural tractors

Sharipov V.M., Nyunin B.N., Kryuchkov V.A., Fedotkin R.S., Alendeev E.M., Timofievskiy A.A.

Abstract

Developing the preselector transmissions for different vehicles, designers of machine-building enterprises face the absence of methods that would allow to define unambiguously the design parameters of those transmissions. Particularly, during determination of shafts arrangement diagram in four-shaft preselector transmissions with not-coaxial arrangement with necessity to keep the minimum overall width, there is the mutual interference of parameters of geometry and arrangement of gear wheels on each other and overall width simultaneously. For the solution of this problem, it is necessary to resort to using of graphical analytic method with a great number of iterations, which is labor consuming and does not provide a guarantee of result repeatability. The article deals with the method that allows to choose the rational parameters of main kinematic links to provide minimum overall width and to define unambiguously their position in space. During method preparation, the authors’ experience in development of transmissions for agricultural tractors of 4 drawbar category was taken into account. The design sequence of preselector transmission is reduced to choice of gear ratios and to forming of rational shafts arrangement diagram, due to which the minimization of overall width of preselector transmission is achieved. It is established that on the basis of kinematic parameters of links, it is possible to form the rhombus that completely defines shafts arrangement in transmission. For complete description of the rhombus geometry and its position in space, the analytical dependences are obtained. As a result, it is possible to determine accurately the overall dimensions of preselector transmission and the distance between input and output shafts without using graphical analytic method. The developed determination method of rational design parameters of preselector transmissions could be used in development of similar constructions for traction and transport machines.
Tractors and Agricultural Machinery. 2016;(10):13-18
pages 13-18 views

Calculation of nominal values of the main indicators of agricultural tractor

Samsonov V.A.

Abstract

As optimal values of the main indicators of tractor (energy intensity, power, operating weight, traction force, working speed) their nominal values are taken. Their calculation is a critical task of tractor theory. The aim of the study is to determine the nominal values of main indicators of tractor for maximum of propulsive coefficient and minimum of energy consumption. The objects of research are a wheel tractor with front steering wheels of smaller diameter than the rear ones and a caterpillar tractor. The main research method is calculation using computer programs with change of indicators by dichotomy method with given step in cycle. Low value of nominal energy intensity is determined by minimizing the function of specific power consumption that is the relationship of energy consumption during cultivating of a unit of area to a unit of performance and a unit of working speed. Low nominal values of power, operating weight, traction force and working speed are determined by the low value of nominal energy intensity, maximum propulsive coefficient and minimum energy consumption corresponding to tractor operation with permissible slipping. To determine the high values of nominal energy intensity a generalized non-dimensional coefficient of tractor efficiency is used, that is geometric mean values of partial non-dimensional coefficients of tractor efficiency on the operating weight, propulsive coefficient, fuel consumption per unit of area, performance, fuel consumption per unit of performance. With increasing of energy intensity the performance of tractor increases, but its efficiency on other indicators reduces. As upper limit of nominal energy intensity, a value is taken in which the reduction of generalized coefficient of tractor efficiency does not exceed 5%. At that the performance increases on 11-19%. Using the adopted optimality criteria, the intervals of changing of the nominal energy intensity of tractors are determined: 15,69-20 W/kg for wheeled tractors; 18,63-26 W/kg for caterpillar ones. For these intervals the nominal values of power, operating weight and working speed of wheeled and caterpillar tractors of 3-6 drawbar categories are determined.
Tractors and Agricultural Machinery. 2016;(10):19-24
pages 19-24 views

Loading conditions of pistons of internal combustion engines and causes of crack formation on combustion chamber edge

Gots A.N., Glinkin S.A.

Abstract

In order to develop the methods for assessment of durability of pistons of tractor diesel engines, it is necessary to conduct the research of causes of failures in their operation, in particular crack formation on the edge of combustion chamber. Tractor engines operate in transient regimes due to periodic changes of control organ position and resisting moment when tractor performs agricultural, logging and other works. In transient regimes, the stress-strain state of piston varies in time, which leads to the formation of fatigue cracks on the edge of combustion chamber. The paper reviews the studies on regularities of change in the rate of propagation of fatigue cracks on the edge of combustion chamber of tractor diesel engine. The peak values of heat flows passing through the heat-absorbing surface of piston head in transient regimes exceed by 2.5 times the same values in steady-state regimes. According to the researches, for the 4ChN 11/12.5 tractor diesel engine stress intensity on the edge of combustion chamber caused by temperature gradients equals to 92-98 MPa, and exceeds more than by 2 times the stresses caused by gas pressure forces in cylinder (38-42 MPa). With the increase of engine forcing, the edge of combustion chamber becomes a local concentrator of thermal stresses, that leads to elastic-plastic deformations of cyclical pattern and microdefects. Stresses appearing on the edge of combustion chamber under rapid change of loading modes typically exceed the values of yield stress of piston material. This leads to the appearance of plastic deformations on the edge of combustion chamber. The analysis of causes of crack formation on the edge of combustion chamber of piston of a tractor diesel engine shows that when assessing the durability of piston, the whole range of indicators and parameters of the engine should be taken into account.
Tractors and Agricultural Machinery. 2016;(10):25-29
pages 25-29 views

Rational choice of parameters of powered disk of a soil cultivation unit

Akimov A.P., Konstantinov Y.V.

Abstract

The paper aims to show the advantage of solution of the non-formal problem of rational choice of parameters of powered disk of a soil cultivation unit when it is formalized as bi-criteria optimization problem in comparison with its formalization as one-criterion optimization problem. An earlier suggested mathematical model of interaction between disk and soil is used. This model allows to determine the driving force and power consumption required for disk motion in soil depending on the parameters determining its operating mode. The taken dimensionless parameters are: the kinematic coefficient equal to the ratio of peripheral disk speed to forward speed of soil cultivation unit, and the relative depth of disk equal to the ratio of its operating depth to its radius. The problem of rational choice of parameters of powered disk is formalized as optimization problems by the following criteria: the maximal driving force; the maximal efficiency coefficient of powered disk; the maximal driving force and efficiency coefficient; the maximal driving force and minimal power consumption for disk motion in soil. The solutions of these optimization problem are obtained. It is found that in the case of two bi-criteria problem statements the compromise curves are almost identical in the parameter plane. It is also shown that the advantage of formalization as bi-criteria optimization problems lies in the fact that it allows to find such values of parameters whereby the required driving force is achieved with maximal efficiency coefficient and minimal power consumption for disk motion in soil.
Tractors and Agricultural Machinery. 2016;(10):29-33
pages 29-33 views

Universalization of plow-bottom surface of working organ of a plow

Blednykh V.V., Svechnikov P.G., Troyanovskaya I.P.

Abstract

Economical cultivation of different soils on different speeds requires working organs with different parameters. Using plows with optimal parameters of plow-bottom surface will allow to minimize the cost of tillage with no loss in quality. Such parameters of working surfaces as setting angles of plowshare, bend of mouldboard and others are considered. Adjustment of working organ of a plow by rotating and offsetting will provide the most useful type of plow-bottom surface and better quality of tillage with the use of a single working organ for different soils and speeds. The paper presents a newly developed way to compare the topology of two plow-bottom surfaces with the use of criterial filter-function, as well as original methods to input the data on the topology of plow-bottom surfaces and to approximate these data by polynomial dependencies for smoothing and providing the unimodality of objective function of optimization when using the Hooke and Jeeves method. The optimal angles of rotation (12 degrees) are obtained whereby the deviations of a comparison plow-bottom surface and a basic one are minimal. According to the agrotechnical and technological requirements on the overlap of operating widths between the working organs, the first working organ of plow should be attached without offset, the second one depending on the realized speed should have an offset of 70 mm, the third - of 140 mm, the fourth - of 210 mm. The practical results of using the developed method for universalization of plow-bottom surface are presented.
Tractors and Agricultural Machinery. 2016;(10):34-37
pages 34-37 views

Increase of abrasive wear resistance of parts by means of variation of welding technique of double-layer coatings with hard surface

Kozarez I.V., Mikhal'chenkova M.A., Lavrov V.I., Sinyaya N.V.

Abstract

The double-layer welding applied for restoration of parts of construction, road and tillage machinery allows to create a coating that resists shock loading and prevents abrasive wear. It is determined by significant differences between the properties of the lower layer that is relatively soft and the upper hard layer. Known researches of this method do not consider the influence of welding technology on the wear resistance of obtained coating in an environment with high content of abrasive inclusions. The aim of the paper is to determine the degree of influence of technological methods of double-layer coatings formation on the wear of parts used in soil medium. The welding was carried out manually during restoration of ploughshares with ray-shaped wear according to four variants of technology. The wear was controlled by weight loss. Experiments reveal that the wear in function of operating time is in straight-line dependence for all technology variants. Operating time before reaching the steady state mode of wear and the limit state depends on welding technique. The influence of methods of coating formation technology on abrasive wear resistance that is due to the difference of thermal influences on weld metal is considered. The optimal technology variant for maximum wear resistance of coating is cooling of each bead by applying both first and second layers. The implementation of such welding technology allows to increase the abrasive wear resistance by 30% in comparison with other methods. The use of double-layer welding technology increases the resource of restored ploughshare by two times in comparison with a factory-made one.
Tractors and Agricultural Machinery. 2016;(10):38-40
pages 38-40 views

Unmanned mobile power unit for agricultural purposes

Godzhaev Z.A., Grishin A.P., Grishin A.A., Grishin V.A.

Abstract

It is shown that the basis of robotic technologies in plant cultivation is an unmanned mobile power unit for agricultural purposes on wheeled or tracked platform with hybrid power plant, motion control and machine vision equipment. Description of software algorithm and schematic circuit diagram of motion control are given. It is noted that machine vision is an integral part of working organs, because much of the information about the state of plants (growth rate, maturity degree, disease) is received through visual contact, as well as through systems of motion control and precise positioning. This information allows the robotic working organs to find the technological solutions and implement the required operations, and the unmanned mobile power unit to move on process route. Another fundamental function of unmanned mobile power unit is positioning and motion control on required trajectory. A brief analysis of implementation of this function by means of satellite navigation or ground facilities of positioning including machine vision and target indication is given. Satellite navigation systems provide positioning and identification on large areas, but do not work indoors. Network wireless system of local positioning allows to control the location and motion of objects and reliably identify them both outside and inside the premises. Combined application of such systems allows to extend the motion control of vehicles and agricultural machines to areas not directly visible for satellites: covered yards, buildings. That creates additional opportunities for control of local movements of products and personnel in industrial and non-industrial premises of closed and open type.
Tractors and Agricultural Machinery. 2016;(10):41-44
pages 41-44 views

Experimental research of conditions of cylinder oil supply in high-speed four-stroke internal-combustion engine

Putintsev S.V., Ageev A.G.

Abstract

The research is relevant because oil supply processes in the cylinders of four-stroke piston engines with traditional cranking mechanism and combined lubricating system are understudied. The research aims to receive the experimental data on pattern of motor oil distribution by circumference of cylinder for the specified type of internal-combustion engine. The measurement method is based on organization of drainage and following quantity control of oil that is removed by piston rings from internal surface of the cylinder. Experimental device corresponding to this method represents the low-sized high-speed four-stroke air-cooled TMZ-450D diesel engine having a cylinder with six oil-catch through holes executed in its bottom support belt and supplied with thin-walled tubes. Tests were performed under rotation of crankshaft by means of outside source (balanced engine) with nominal speed. The oil filling of any first of six tubes was considered as a moment of ending for each experience. The quantity of oil in tubes was controlled by measuring of oil column length in every tube. During cranking both with air compression and without it, experiments show that quantity of motor oil removed by piston rings from non-loaded cylinder wall side in all cases is more by 15-18% than from the loaded one. Such pattern of oil distribution by circumference of a cylinder at which non-loaded side receives more oil than the loaded one, points to the infringement of principle of coordination between lubricating and loading conditions. That increases the risk of wear and bore scuffing in cylinder-piston unit. In spite of limitation by only one method and one object, the received results show the expediency of following studies of features of cylinder oil supply for the specified type of engines to increase their work reliability.
Tractors and Agricultural Machinery. 2016;(10):45-49
pages 45-49 views

Noise in cab of a crawler agricultural tractor

Belyy I.F., Bogdanova I.A.

Abstract

The working conditions of operator are considered as one of the most important indicators of technical level of a machine and its competitiveness in agricultural machinery market. The article presents the measuring data of noise level on operator workplace, based on the results of long-term tests of crawler agricultural tractors of 3 drawbar category for general purposes. Measurements of noise level in tractor cabs were carried out according to the requirements of state standards when performing the main type of works, namely the stubble tillage after harvesting of spiked cereals. Tractors produced by Volgograd tractor plant in 1993-2000 conformed to the sanitary regulations of tractors’ and agricultural machines' technology and had the noise level about 78-80 dBA. Subsequent upgrading of crawler tractor’s cab led to worsening of work conditions in respect of noise. Noise level in cab of the Agromash-90TG 1040А tractor produced by Volgograd tractor plant in 2012-2015 reached 88-90 dBA. The analysis of the results of measurement of noise levels allows to make a conclusion that the main noise source in upgraded cab is the exhaust tube of engine. The construction of cab does not protect the operator against the noise of engine. Furthermore, the use of microclimate normalization system in cab of the Agromash-90TG tractor does not provide the reduction in air temperature to a comfortable level of 24-27 degrees C. Test results revealed that working conditions on the new tractor do not conform to the requirements of standards. Specialists of tractor industry organizing a new production of crawler agricultural tractors should take into account the previous experience of engineering developments in Volgograd tractor plant and results of state tests of tractors.
Tractors and Agricultural Machinery. 2016;(10):50-52
pages 50-52 views

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