Vol 83, No 8 (2016)

The article describes the present state of mechanization of horticulture and fruit-tree nursery, analyses the mechanization of technological process of parent bushes hilling. Production of planting material for establishing new type orchards depends on the degree of mechanization of technological processes in fruit-tree nurseries, more specifically on the availability of special equipment for work in mountain and foothill areas on stony and heavy soils. At this stage, the urgent task is to increase the efficiency of work of fruit-tree nurseries with simultaneous reduction of labour and power intensity by means of mechanization of production processes based on new technologies and technical tools for cultivation of planting material. The new type orchards, as a rule, are short-growing, high-yielding and require a 5-6 times bigger planting stock compared to old type orchards. Therefore, it is necessary to intensify the production of transplants in fruit-tree nurseries of a new type, and to lay for it the industrial foundation with the use of mechanization means for the care of parent bushes. This intensification is only possible on the basis of application of modern industrial technologies of reproduction of planting material taking into account the landscapes of the Republic of North Ossetia - Alania and the use of high-performance agricultural machinery, tractors and other equipment. The article proposes a technology and a combined unit for parent bushes hilling and row spacing cultivation, as well as a tent for budding of planting stock of fruit and berry crops when establishing the new orchards up to world standards. These devices allow to increase labour productivity under production of planting stock in conditions of mountain and foothill areas.

The check of compliance with legislative requirements for vibration protection of operators is carried out at the stage of certification testing of new and upgrading products. At this stage, the further development is associated with high time and material costs. The article substantiates the possibility of use of a calculation and experimental method which allows to determine at the development stage the level and frequency content of potentially dangerous sources of vibration; to develop a computer model for the system «excitation source - frame - cab - antivibration seat - operator»; to make out proposals to comply with legislative requirements by means of parametric forecasting. As an example, the problem of vibration in the low frequency range of 2-14 Hz is considered. This vibration is the result of the process of rolling of track rollers on track chain that lies on the yieldable soil foundation. According to biomedical research, the resonance frequencies of critical parts of human body are in this low frequency range, which is displayed in sanitary norms. Based on the analysis of field test results, the kinematic impact of track rollers on tractor frame is represented as stationary narrow-band random processes. Mathematical model of the system is described by a set of differential equations with random input processes. The methods of statistical dynamics are used to implement the model. The simulation results are presented as a set of transfer functions. They represent the distribution of resonance frequencies of angular and heave oscillations of the separate system elements and the spectral density functions. These results allow to obtain the quantitative estimations in the form of mean-square values of the output processes. The use of this approach allows to solve the problems of vibration protection of operator at the stages of design and testing of prototypes of road-building machinery. It is achieved by tuning-out of the system «track assembly - frame - cab - antivibration seat» from resonance phenomena and by introducing some design solutions.

During the primary cultivation by means of general-purpose ploughs, the circular disk knives do not provide a reliable cutting; with that, the traction resistance of plough is increased, productivity and quality of its work are reduced. The purpose of the research is to increase the operational efficiency, the quality of soil cultivation and to reduce the energy intensity of general-purpose ploughs equipped with disc knives. Different designs of knives are studied in order to find the optimal shape providing a reliable pinching of plant and straw mass. A formula for determining the angle of pinching of a polygonal disc depending on the cultivation depth and number of angles in the polygon is given. The studies show that the hexagonal disk knives have the minimum angle of pinching, thus this shape is rational. The operating conditions are defined, in which the stalks of straw mass do not slip out of the knife blade when cutting. Motion paths of blades of hexagonal and circular knives at different positions of the instantaneous center of disk rotation are studied graphically. An empirical formula is obtained; dependences of pinching coefficient on the position of instantaneous center of disk rotation are constructed. It is found that with decreasing of nominal diameter of a knife the pinching coefficient is increased, and the quality of pinching of crop materials is improved. As a result of the research, the dependences are obtained showing that the areas of reliable pinching and cutting linearly depend on the kinematic parameter. With the cultivation depth of 0.08-0.12 m, the efficiency of pinching of hexagonal knife is increased by 1.8-2 times compared to the circular one.

The article shows the effect of compacted soil lump which forms on the blade and in front of it on the characteristics of performance and lifetime of soil cutting working organs. Facts proving the presence of compacted soil lump on the blade in process of cutting soil layer are given. The results of theoretical and experimental researches are brought, allowing to obtain the design parameters and to improve the technical level of working organs used in soil cultivating and cutting. Negative factors that affect the efficiency of parts of tillage equipment in the conditions of compacted soil lump effect are substantiated and listed. The cyclical nature of its formation on the blade cutting the soil layer is noted. The article presents a hypothetical scheme of soil lump effect on the blade of working organ with different degrees of bluntness. This scheme explains the physical meaning of negative effects that are associated with deterioration of energy and agronomic indicators of parts and equipment during the operating wear in conditions of clear-cut compacted soil lump (on relatively strong soils). The article determines the fundamental reasons for the sharp increase in resistance of soil in the presence of chamfered edge on the blade of cutting working organ, which is associated with movement of compacted soil lump under the blade. Regularities defining the values of specific loads acting on the blade are given. The differences in variation of total and specific loads on working organ under formation of compacted soil lump are noted. The article substantiates a special role of the rear face of the blade of working organ in connection with heavy conditions of loading of soil layer under it. It describes the practical design and technological methods of protection of parts against the effects of compacted soil lump. Substantiated values of the parameters of working organs of agricultural machines interacting with soil are given, that provide the increase in their operational, agronomic and life characteristics.

Promising directions of design improvement of combine harvester by means of the maximal adaptation of algorithm of its impact on plants with different physical and mechanical properties are presented. The technological algorithm of work with grain heap is optimized. It is proposed to separate previously the light impurities directly in the stripper header, the rear wall of which should be equipped with inertial tilted-plate separator. The light impurities are removed along with excessive airflow from the stripper header, but heavier free grain and tailings remain inside. In the terms of design, such technical effect is achieved due to the fact that the separator is formed by a set of longitudinal plates mounted with overlapping and imbedding of greater part of the cross section of each of them into the body of stripper header. The cross section of the plate has a curved surface, and its concavity is oriented towards the rear wall of the body. Remaining grain heap (tailings and free grain) is subjected to the secondary separation on perforated bottom of grain conveyor. Elongated holes are made in bottom; they have a particular cross-sectional shape and are inclined from the motion direction of conveyor flights on acute angle. As a result, the awns of spikes do not catch hold of the rear edge of the hole, and climb up the angled surface to the level of bottom of grain conveyor. Implementation of set of these technical solutions in the design of modern combine harvester will increase its performance when stripping of standing plants with eliminating the possibility of free grain crushing by working organs of the threshing device.

The results of the studies of mechanochemical activation of motor fuels aimed to increase their calorific value and reduce their consumption in automotive internal combustion engines are summarized. Traditionally, the improvement in fuel efficiency and environmental friendliness of such engines is achieved by high-tech modernization of fuel systems. But it can also be achieved by modification of fuels that changes their properties and increases the calorific value. By means of methods of mechanochemistry, using the equipment with low power consumption and a simple process, the mixtures and separate oil fractions are destroyed with the formation of low molecular homologs, as well as hydrogen and carbon. The degradation of saturated hydrocarbons is the breaking of chains, and unsaturated ones are destroyed through the formation of saturated products. The hydrogenation by degradation products of the starting material is possible. The mechanochemistry of fuels is investigated on the example of a combined static mixer-activator. The activator in the form of cylinder of 150 mm length and 30-50 mm diameter is used for modifying motor fuels; it has three serial camera, embeds in any of the fuel systems of internal combustion engine, does not require the drive, is free of chemical substances, does not affect the performance of gasoline, diesel fuel, aviation kerosene, fuel oil, does not reduce the engine lifetime. The tests were performed on a test bench with YaMZ-236 diesel engine using three different diesel fuels, at first with installation of activator in the fuel supply line of fuel high pressure pump, and then in its main drain line. When idling of diesel engine with engine speed of 900-1300 rpm, the reduction of activated fuel consumption on average by 26.3% is revealed in eleven tests. The methods for improving the calorific value of fuels by different impacts are reviewed.