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.

In seed-production farms, the temperature of drying agent is often limited by the maximum permissible temperature of heating; the simultaneous moisture removal is 3-6%; seeds are dried to a moisture content that exceeds the normal one by 2-3%; the layer is stirred several times during drying process. All of this increases the process cost and could lead to crop losses. The paper analyzes the essential factors influencing the safe drying of seeds in dense layer. It is found that along with the maximum permissible temperature of heating, account must be taken of the rate of dehydration, the specific surface of seeds, the heat transfer coefficient and the unevenness of moisture of basic material and of a dried-up one. The estimation of parameters for safe drying of seeds is carried out on the basis of mathematical models and well-known empirical expressions of the heat resistance and maximum permissible moisture removal. The article proposes the calculation of drying agent temperature that ensures the complete safety of the process, for breeder seeds also. Permissible temperature of drying agent is calculated by the expression that takes into account the specific surface of grain, the heat transfer coefficient, the heat of vaporization and the coefficient that depends on the permissible rate of dehydration, as well as the maximum permissible temperature of seeds heating. The maximum height of the layer of seeds being dried without stirring depends on the speed of drying agent, the diameter of grain, the porosity of layer, the mass transfer coefficient and the moisture content of drying agent before and after the layer. The maximum permissible temperature of seeds heating should be calculated according to the formula of S.D. Ptitsyn, but the maximum humidity of 10% of weighed portion should be used as a basis.

Such operational parameters of small-scale mechanization means as grasp width and motion speed of a unit equally affect the machine performance and thereby determine its complex quality. The improvement of machine performance due to the extension of grasp width is reached by the use of three-, five-, six- and eight-furrow ploughs. This direction requires the constant increasing of traction force of power vehicles due to the increasing of engine power and trailing weight, which finally change the operational qualities of machine. Other direction of performance improvement is due to the increasing of operation speed; it is more complicated because when the speed increases, the traction resistance of working organs of tillage machines rises sharply, and the quality indicators of ploughed soil structure worsen. The transition to higher speeds of tillage requires a complex solution of such scientific and technical problem as development, creation and introduction of essentially new tillage machines for small-scale mechanization means. Special attention should be payed to a method for improvement of the engine power use by means of its transferring to working organs of the machine not through a hook but through a power shaft. Soil reaction to the active working organs is directed towards the power vehicle motion, therefore the trailing weight loses its functional necessity. It will allow to reduce the metal consumption of construction of small-scale mechanization means.

Foreign methods of tractor drawbar testing do not allow to evaluate the performance capabilities of movers and drive system in general with a number of other common characteristics, because of using a tar makadam as a surfacing. Methods of tractor testing used in Russia provide the experiments on real soils and aiming to a wide variety of the country's natural environments. But even these tests do not give a full picture of performance of a machine-tractor unit. Tractor is a multipurpose machine that aggregates with a variety of implements that have a wide range of draught resistance. Therefore, during aggregation it is necessary to load tractor’s axles efficiently. Tractor ballasting increases the rolling resistance force that affects negatively on the propulsive efficiency. In most cases, the front ballast is not removed and remains on a tractor permanently, which increases the fuel consumption. There is a search problem for technical solutions that would optimize the tractor performance without using front ballast. For solving this problem, it is proposed to improve the methods of drawbar testing by directing of pulling force at the angle. If this angle is controlled, it is possible to load a front axle without ballast. In this case, the rear axle is loaded, and its trailing weight is decreased. Additional loading of the rear axle is adjusted by adding ballast weights to the rear wheels or on a cross bar of lower arms. For each case of loading by pulling force, it is necessary to provide the proper rational weight distribution to achieve the highest propulsive efficiency.

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 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.

Nowadays the trend of development of combined units and devices for implementation of specified technological processes is widely spread. The use of combined working organs for graded subsurface tillage allows to reduce the energy and labor costs and to improve the technological process. Based on the comparison methods and monographic survey of existing designs of working organs, their shortcomings when using in arid conditions are revealed. It has been established that in such conditions it is advisable to apply graded subsurface tillage. The analysis of designs of working organs for graded tillage is performed, it allows to establish the advantage of curved elements for surface tillage. A number of shortcomings of subsurface cultivating working organs that have been revealed during years of researches allows for the conclusion about the prospects of replacing blades on curvilinear rippers for surface tillage. The data of content of valuable soil aggregates as a percentage of absolute dry chernozemic soil are given. Based on the analysis of the data, it is established that layer structure can be improved through the use of an element for surface tillage to the depth down to 16 cm in design of chisel working organ. The expediency of mounting of elements for deep and surface tillage on the same tine for graded subsurface tillage is proved. The scheme of a combined working organ is proposed: a chisel for deep tillage and a curvilinear ripper for surface tillage are mounted on its tine, which provides the required crumbling of layer.

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.