Vol 89, No 2 (2022)

90 years ago, in 1932, Design and Experimental Department (DED STP) was established at Stalingrad Tractor Plant – the first specialized design department of tractor engineering in our country. During the time of existence of this department, the factory chief design engineers were V.G. Stankevich (1932–1938), M.M. Romanov (1938–1940), V.A. Kargopolov (1943–1949), A.K. Platonov (1949–1950), A.Ya. Merilov (1951–1957), M.A. Sharov (1958–1980), V.P. Shevchuk (1980–1996), V.Ya. Bokov (1996–1998), I.A. Dolgov (1998–2005), V.V. Kosenko (2006–2010). The article contains the review of main achievments, made by the department, led by each of them. Throughout these years 5 families of tracked agricultural tractors were developed at Stalingrad (Volgograd from 1961) Tractor Plant, such as STZ-NATI, DT-54, DT-75, DT-175S and VT-100, with a wide range of special modifications (transport, swamp, hillside, peat, plowing and cultivating, etc) and configurations. Short stories of the creation of these machines, their characterisics and advantages over the predcessors are given. The tractors of STP (VgTP) were used in agriculture as well as in many other areas of our country’s economy, were exported to foreign countries and deserved respect and love from tractor drivers and maintenance specialists. Overall about 4 million tractors were produced according to technical documentation, developed by design engineers of STP (VgTP) or with their direct involvement.

BACKGROUND: When conducting experimental studies aimed at finding optimal parameters of the diesel engine operating mode, as well as other objects, the issue of reducing the volume of the experiment becomes acute. The use of modern methods of planning, obtaining, processing and analyzing experimental data allows to reduce significantly the number of experiments conducted without notable loss of the reliability of the data obtained.

AIMS: The aim of this study is to determine the optimal operating characteristics of the diesel engine, which uses the multi-component bio-fuel composition.

METHODS: In order to determine the optimal values of the main parameters, affecting the effective indicators of the 4ChN 11.0/12.5 diesel engine when operating on the multicomponent biofuel composition and a mathematical description of their relationship, a second-order three-factor Box – Benken plan was implemented. These factors are effective load, crankshaft rotational speed, and fuel injection advance angle. The diesel engine operation studies were performed on the most stable mixture of the multicomponent biofuel composition, including the following ingredients, wt %: rapeseed oil – 34.5; ethanol – 31.0; diesel fuel – 34.5. The search of a compromise solution for the optimal combination of the levels of studied factors was performed with the method of superimposing of bidimensional sections of the response surfaces of the effective efficiency factor and the specific effective fuel consumption.

RESULTS: Adequate models of second-order regression analysis of changes in effective efficiency factor and specific effective fuel consumption have been obtained. The factor space is described and grapho-analytical studies are carried out. The analysis of regression models and bidimensional sections of response surfaces allowed to determine the optimal values of the studied factors. The method for determining the optimal load and speed ranges of the diesel engine operation, using the multicomponent biofuel composition, has been optimized due to the application of the experimental plan and the description of the factor space by mathematical models, while number of experiments was reduced.

CONCLUSIONS: The optimal area of the combination of the factors is in the range of varying the rotational speed of the diesel engine crankshaft n=1400...1550 rpm and the effective load P_e=0.68...0.85 MPa at the fuel injection advance angle Ѳ_inj=23.5 degrees to TDC. Considering the variable nature of the load and speed modes of a diesel engine in a real operation environment, the obtained data are of practical interest.

BACKGROUND: The issues of choosing reasonable properties for suspension system of wheeled vehicles, including vehicles for agricultural purposes, still remain relevant, especially for the vehicles, which load capacity is comparable to their curb mass. Significant difference between static loads, acting in suspension under the curb and total masses of a vehicle, is a consequence of high load capacity. Two or three times difference is possible (depending on axles load distribution), whereas 70% to 80% of mass of trailing load is on rear axles. Use of convenient suspension systems with metal springs is not able to ensure demanded nonlinearity of properties, where non-zero static wheel travel under the curb mass is kept with reasonable value of period of vertical eigenmodes for curb-massed and total-massed vehicle as well as with dynamic factor value. Air springs with two pressure stages are more advanced solution, as they allow choosing stiffness for small and large wheel travel by means of operation of different pressure stages, which volumes are conditioned by differents stiffnesses in area of static displacement.

AIMS: The aim of the study, which results are given in this paper, is to develop the method of determination of main design parameters and characteristics of air springs with two pressure stages (stiffnesses) and counterpressure, applicable for ensuring non-zero static wheel travel of curb-massed vehicles with keeping the given value of dynamic factor.

METHODS: The analytical analysis methods are used.

RESULTS: An example of implementation of the developed method for the KamAZ-53215 Sel’hoznik truck is given as the study result.

CONCLUSIONS: The dependencies, presented in the paper, make possible to determine main design parameters of uncontrolled air suspensions with two pressure stages (and stiffnesses) and counterpressure for wheeled vehicles, which give an opportunity to ensure given values of static wheel travel and dynamic factor and, in addition, provide insignificant increase of stiffness in comparison to air suspensions without counterpressure.

INTRODUCTION: The paper presents the operating conditions of tractor diesel engines that cause the appearance of thermal fatigue cracks on the edges of the piston combustion chamber. The presence of sharp edges of the combustion chamber in the pistons, which are stress concentrators, leads to an increase in the probability of their destruction and thereby limits the engine life of the diesel engine. The main reasons for the formation of cracks in the zone of the edge of the combustion chamber are indicated.

AIMS: The aim of this study is the assessment of the temperature state of pistons of the D-240 and the D-245 tractor diesel engines, produced by Minsk Motor Plant (MMP).

METHODS: Temperature gauging was carried out according to the method in order to identify the nature of changing of piston heads temperatures under stationary and nonstationary operation modes of diesel engines. Transfering of thermal electromotive force from thermocouples to measuring devices was carried out by means of an intermittent current collector. Imitaion of nonstationary operation modes was carried out by means of changing the cyclic feed of a high pressure fuel pump, using a reversible electric motor.

RESULTS: The data of the temperature state of pistons under various stationary and nonstationary operation modes of engines is provided. It is noted that the temperature state of the D-245 diesel pistons has a higher level of heat stress compared to the D-240 diesel pistons. The maximum amplitude of low-frequency temperature fluctuations at the edge of the combustion chamber and their radial differences along the piston bottom are determined, depending on the parameters of thermal loading cycles. It is noted that the most dangerous modes of diesel operation, in terms of the destruction of the edge of the combustion chamber, are sharply changing modes (eg.: the“loading – unloading” mode).

CONCLUSIONS: It is proposed to increase the fuel injection advance angle in the thermal loading cycle in order to conduct accelerated comparative tests of piston variants for thermal resistance. The developed thermal loading cycle, in which the total duration of the load increase is 180 s and the total duration of the load decrease is 90 s, can be recommended for accelerated motor tests of pistons for thermal cycling resistance. The obtained temperature measurement data is recommended to clarify boundary conditions of the first kind when calculating the piston using the FEM method.

BACKGROUND: Organic, mineral and organomineral fertilizers in both granular and powder form are used in agricultural production in order to increase of soil fertility significantly, as well as to replenish soil reserves of micro-, meso- and macroelements. For fertilizer screening on a surface of a field, agricultural producers use machines with centrifugal-type working bodies which have horizontal or vertical rotation axis. In pursuance of the task of reducing the shift time consumption, a number of researchers find it reasonable to use a low-frame design of the machine to make direct loading of it from the dump truck body possible. For machines, having such design, rotary spreading working bodies with blades on a horizontal rotation axis are the most suitable.

AIMS: The article is concerned with the justification of the design parameters of the blades of the rotary spreading working body of the low-frame body spreader of solid mineral and organomineral fertilizers.

METHODS: The length of the working surface of the rotor blade with a horizontal rotation axis is justified theoretically for the most uniform distribution of solid fertilizers. An example of calculating the length of the blade of such a device based on the previously established overall dimensions of the spreader is given.

RESULTS: On the basis of experimental data, the expediency of using trough-shaped blades with a length of 110 mm was confirmed. The most effective design parameters of the dimensions of the rotor blades for screening fertilizers were established, taking into account the reduction of possible options for fertilizer granules crushing by means of preventing their recirculation inside the rotor casing. The relevance of research of devices with rotary working bodies on horizontal axes of rotation is argued.

CONCLUSIONS: Possible prospects for future research and the possibility of further improvement of the low-frame granular fertilizer spreader are proposed.

BACKGROUND: The solving of priority tasks for the development of the agro-industrial complex considers the creation of advanced scientific developments. Innovative research of technical means and technologies of mechanization of agricultural production is not an exception in this regard. In the agricultural sector of Russia, crop production occupies a key place, in which the cultivation of grain crops is a priority. In the whole range of operations in the production of grain, the most important part of it is post-harvest processing of grain. One of the main stages in the post-harvest processing of grain is drying, in which the raw materials are brought to the moisture regain (down to 14%). Proper preparation of grain for storage ensures its reliable safety.

AIMS: Modernization of the granular materials dryer by means of new technical solution at the level of patentability.

METHODS: Research of the state of the issue on the topic under consideration with the help of a review of literary sources. Patent search for technical devices of grain dryers. Studying the principle of their functioning and design features. Analysis and generalization of the material for the adoption of a new design solution.

RESULTS: The use of innovative technologies with the new generation harvesters, characterized by high productivity, has significantly reduced the duration of harvesting, and this, in turn, has significantly aroused the interest in drying. The use of dryers with improved quality indicators of functioning significantly reduces the time for preparing raw materials for long-term storage, reduces grain losses in the field during harvesting, and, in addition, makes it possible to carry out the process of transferring grain from the field to a special long-term storage warehouse in the shortest possible time and with the least losses. There are various ways of drying granular materials. These are main methods based on increasing the temperature of the processed material. Drying of grain with the help of heated air has become the most widespread.

CONCLUSIONS: As a result of the conducted research, the drawbacks of existing technical devices for granular materials drying, as well as the principles of their functioning, have been revealed. A detailed analysis of literary sources, including a patent search, made it possible to upgrade the processed raw materials dryer, characterized by a simple and reliable design.