Centrifuges with hydrojet drive were widely used in 1960-70 for oil cleaning in the engines. Nowadays some foreign companies apply them together with filters for oil cleaning in engines of vehicles and tractors. The most complex challenge in designing such centrifuges is the calculation of parameters of nozzle diaphragm. Its optimal solution depends on the specific technical requirements to separator under designing. Research objective is to substantiate the optimal geometrical parameters of hydrojet drive of cleaning centrifuges, and to develop its calculation method under different conditions of designing. Design parameters of hydrojet drive, such as nozzle diameter and its reactive arm, are calculated according to the condition of dynamic balance between the drive moment created by the liquid from nozzles, and the moment of resistance to rotation at the stable motion. Design, kinematic and power parameters of nozzle diaphragm that provide the driving kinetic moment of liquid are analyzed. The factors influencing on rotational resistance are determined. As a result, the equation of balance of specific energies is received: the energy spent for overcoming of rotational resistance, and the motive energy of fluid flow developed by hydrojet drive. The analysis of this equation allows to determine the optimal reactive arm and nozzle diameter. Formulas for calculation of minimal fluid consumption in hydrojet drive that provides the specific angular speed of rotor and the parameters of nozzle diaphragm corresponding to this consumption are received. With optimal design parameters of hydrojet drive, the coefficient of utilization of flow energy is maximal. The expression for calculation of the maximal efficiency coefficient of hydrojet drive is obtained. Results of theoretical researches are presented in graphic form. Design charts of optimal values of flow rate of liquid from nozzles, circumferential speed of nozzles, reactive arm, and also efficiency coefficient of hydrojet drive with its optimal parameters are given. A method and solution algorithm of two problems of hydrojet drive design are offered: the calculation of optimal design parameters of nozzle diaphragm for ensuring the maximal rotating speed of rotor, and also the calculation with the minimal power consumption of drive.

Reliability of results of computer simulation depends on the accuracy of specified dynamic characteristics of the elements of oscillating system. In this connection, identification of model parameters and verifying of its adequacy are of major importance. Bench tests of new elements of vibration protection of T-11 tractor cab and seat involving the hydropneumatic way of vibration damping were conducted. The equipment of test bench conforms with loading scheme of investigated elements and reproduces the cab and seat working conditions identical to these of tractor operation, in particular the impact of given random process and shock loading. The information-measuring unit provides the registration and processing of experimental data. Bench tests allowed to reveal the fundamental features of the dynamic characteristics of shock absorbing elements, determine the numerical values of parameters contained in them and substantiate a number of assumptions inherent in the mathematical model. Adequacy check of the model was made by comparing the simulation results with field tests of T-11 tractor. The layout of acceleration sensors at various points of the tractor allowed to describe quite adequately the overall picture of vibration loading of the system of «caterpillar truck - frame - cab - seat», and to reveal a number of regularities that correct the model and perform a comparison of simulation results and field tests. The laboratory tests of vibration protection elements for operator workplace increased the accuracy of simulation results. Field tests allowed to confirm the adequacy of calculation model. The possibility of substitution of the field tests for laboratory ones in case of determining a number of certification characteristics of vibration protection systems is substantiated.

Powder frictional materials are widely used in frictional couplings and brakes of tractors, automobiles and agricultural machinery. Today various terms are applied for these materials, such as: "ceramic-metal frictional material", "powder frictional material", "sintered frictional material". The term "ceramic-metal frictional material" is the most frequently used in scientific literature. Long-term experience of development and use of frictional materials indicates that the listed terms are not exact. There is the following definition of metal ceramics. It is the artificial material having heterogeneous composition of metals and alloys with nonmetals (ceramics). In modern sintered powder frictional materials the quantity of nonmetallic components could range from 10 to 30% of volume, including graphite, oxides, nitrides, sulfides and other components. For example, the volume of the most widespread composition of MK-5 sintered powder frictional material based on copper contains 23% of graphite that does not interact with the bronze base. According to earlier formulated definition of "ceramic-metal frictional material", the graphite should be qualified as ceramics, which is absolutely incorrect. When studying a microstructure of MK-5 sintered powder frictional material based on copper, it is established that graphite is uniformly distributed across the section surface. It does not interact with the components of frictional material and has the form of isolated particles. Therefore, it is incorrect to define this material as metal ceramics. For these materials it is suggested to use the term "sintered powder frictional materials" that indicates their application and production technology.

Wear intensity of working surface of a part is the major factor influencing its durability. To reduce the wear of parts of working organs of tillage machines, a number of processing methods of their hardening is created; one of them is welding reinforcement. The assessment of ploughshare thickness wear and of influence of its surface reinforcement on wear intensity is carried out. Ploughshares in as-delivered condition and ploughshares after reinforcement according to three processing methods are used as objects of the research. Wear of reinforcing beads height and wear of ploughshare thickness between them are determined. Attrition of the beads occurs unevenly along the length of sock because of the high pressure of soil on ploughshare sock. It is also necessary to consider the fan-shaped soil movement along the ploughshare sock. It is shown that reinforcing beads essentially slow down the abrasive wear of ploughshare thickness between them. That is related to the fact that riffles create the conditions for the formation of fluidized layer between them, and thereby less soil particles get into contacting area. The quantity of abrasive particles contacting with working surface and their pressure on ploughshare body are decreased. When attrition of welding bead is flush with working surface, the composite surface is formed; thereon the maximum hardness is observed, which contributes to the increase in abrasive wear resistance. Traces of reinforcing beads with high degree of hardness also have a positive effect. Due to breaking-in of surface and forming of composite surface, the wear intensity decreases.

To reduce the coalescence activity of drops in the slot spray cones of working fluid, a method of injecting of air jet by pneumatic device with subsequent transporting of air-and-drop flow to the plants is proposed. Reducing of coalescence of drops is proved by comparative data on the density of the covering of record cards using the developed method and traditional one. In case of the developed method, the spraying is carried out by means of pneumohydraulic devices at average unit speed of 19 km/h. In this case, the number of small and medium drops with trace diameters from 0 to 150 micrometers is increased, and the number of drops larger than 300 micrometers is decreased. With the average unit speed of 15.5 km/h and operating width of single pneumohydraulic device of 300 cm, the spray material consumption is 16.26 cubic decimeters on 1 hectare. In the traditional version of arrangement of sprayers on the boom at a pitch of 50 cm and motion speed of tractor unit of 14.8 km/h, the spray material consumption is 51.1 cubic decimeters on 1 hectare, which is by 3.14 times more than in case of the developed method. The advantage of the developed method of drops application on the treatment objects lies in the fact that the outer part of air jet emerging from the nozzle of pneumohydraulic device prevents the entrainment of drops into the environment. The results of these studies and laboratory tests are the basis for further research and practical application of economical, eco-friendly and high-performance technologies of use of pesticides in crop production.

Tuberous roots obviously benefit in comparison with other feeds, due to the high level of specific volume energy, productivity and good digestibility. When they are mixed with other components, the palatability of finished mixtures for animals increases. The quantity of digestible nutrients in tuberous roots can reach up to 90%. To make the nutrients more fully digested by animals, the correct preparation for feeding is necessary, including chopping. One of the problems of roots cutting process is the increased exudation, which results in undue losses of vitamins. Therefore creation of choppers providing the required quality of finished product is a crucial task. The aim of the research is to determine the optimum angle of inclination of the wall of charging hopper depending on the size of tuberous roots and on the offset of horizontal knife of a chopper. Brief description of the developed chopper of tuberous roots is given, as well as the sources of information containing the detailed description of the installation and its operation principles. In the process of theoretical calculations, the scheme of all forces acting in the moment of tuber pinching between the wall of charging hopper and the horizontal knife is drawn; the chain of discourse and theoretical reasoning are shown in detail. As a result of calculations, the analytical dependences are obtained through which assigning the thickness of slices and sizes of chopped tubers, it is possible to calculate the desired inclination angle of wall of charging hopper. Under estimated values, the tuber does not roll over the cutting knife, and the deformation is minimal. Therefore the exudation decreases, and nutrients losses are minimal. On the basis of the derived dependence, the graphs and their analysis are given.