The fuel evaporation in combustion chamber of diesel engine is decisive for the subsequent destruction of fuel molecules. The evaporation process in combustion chamber of diesel engine operating on alternative fuels is understudied. The paper is devoted to the theoretical study of evaporation process of ethanol and rape oil in combustion chamber of diesel engine. It is assumed that fuel spray consists of a great number of identical droplets. The diameter of these theoretical droplets is equal to the average volume diameter of real droplets. A mathematical model given in the paper takes into account the physical characteristics of fuel, design features of sprayer, temperature and pressure of gases in combustion chamber. The engine performance (temperature and gas pressure in combustion chamber) has been determined on a test bench in the Vyatka State Agricultural Academy. The engine worked on rape oil and ethanol with the use of binary system of fuel supply. The paper presents the results of theoretical calculations of evaporation of rape oil and ethanol in combustion chamber.

The aim of the paper is to find the mathematical dependence of temperature of heat-receiving surface of heat accumulator of a solar collector on its operating time under conditions of variable external factors. In this case, variable solar activity throughout the day is considered as the key external factor. Air solar collector with heat accumulator is a basic element of solar power plants intended, for example, for grain drying, water heating, natural ventilation systems of livestock houses etc. By the example of operation of a drum solar grain dryer with water heat accumulator, the differential equation of heat balance of solar collector is obtained. The equation takes into account the following components of heat balance: amount of heat coming into solar collector with atmospheric air; amount of heat coming from solar energy and absorbed by heat-receiving surface of water accumulator; amount of heat taken away by drying agent (warmed-up atmospheric air) after heat exchange with heat-receiving surface; amount of heat for heating of accumulator walls; amount of heat for heating of water in accumulator; external heat loss. On the basis of available experimental data, it is assumed that water temperature in accumulator is directly proportional to the temperature of its walls, and the enthalpy of atmospheric air is proportional to the flow density of solar energy. Required dependence of temperature of heat-receiving surface of a heat accumulator is found by solving the Cauchy problem for differential equation of heat balance of solar collector. The obtained exponential expression connects the parameters of variable external factors with design and technological parameters of a solar collector. This allows to model the output thermal performance of solar power plants used in agriculture depending on various external conditions.

The article explores the startability of diesel engine with and without turbocharger under cold conditions. It is known that under subzero temperatures typical for many regions of Russia, the startability of diesel engines is significantly deteriorated. The aim of research is to study the impact of supercharger on startability of diesel engines. In the process of experimental researches by means of light-beam oscillograph, the indices characterizing the starting sequence have been received, namely: rotational frequencies of crankshaft and turbocharger rotor, air output, time of starting, cylinder pressure. It is found that the startability of engine with supercharger conforms to the state standard requirements at the temperature of 8 degrees C below zero, whereas the startability of engine without supercharger conforms to these requirements at 12 degrees C below zero. The starting time of turbocharged engine is extended due to the resistance in inlet line, that leads to increase of inlet manifold vacuum, to decrease of final compression pressure and therefore to decrease of maximum cylinder pressure. The article determines the operation modes of turbocharger at the starting time and at post-launch warm-up. It is found that operating in these modes leads to the shortage of oil in turbocharger bearing under cold conditions. The research has shown that turbocharger mounted on the engine causes the significant reducing of delivery ratio, and therefore the deterioration of startability. Sustainable startability is possible with installation of circulation valve on engine inlet manifold or compressor, and also with use of turbocharger that can be switched off. It is found that turbocharger can operate in the mode of oil starvation at the beginning of post-launch warm-up under cold conditions. In order to reduce the wear of sleeve-shaft coupling, it is recommended to change the current scheme of oil filling or the design of turbocharger to provide oil inlet directly to turbocharger bearings in the moment of starter switching-on.

The article deals with the kinematic analysis of forwarder crane; it determines the parameters of extension of hydraulic-cylinder rods for execution of defined trajectory of grapple motion. The current systems of forwarder crane control do not allow an operator to realize optimal trajectories and speed ability of motion of crane links. This disadvantage can be partly corrected, for example, with the use of automatic control of crane motion in certain phases of technological cycle. The analysis of matched connection of hydraulic cylinders of a typical forwarder crane is presented in the article. It determines how hydraulic-cylinder rods should move to provide the linear trajectory of grapple at the stage of motion from the moment of log gripping to the moment of its lodging in the middle of upper edge of a forwarder load space. It is necessary to provide a smooth acceleration at the start and a smooth deceleration at the end of grapple motion. The hydraulic-cylinder rods should also smoothly accelerate at the start of motion and smoothly decelerate at its end. The kinematic analysis uses well-known methods that are presented in the article in shortened form. It is shown that for typical design of a forwarder crane both conditions of smooth motion and linearity of trajectory cannot be fulfilled simultaneously. The results can be used for developing the algorithms of automatic control of crane at a separate phase of log loading when there are numerous points of log gripping (gripping control provided by operator) and one delivery point. There is no necessity in additional systems of environmental objects recognition at this phase, that allows to integrate these algorithms into the control system of a forwarder by low-cost facilities.

The service life of engines and transmissions of agricultural machinery and equipment depends on wear intensity of their interacting parts (friction units). In its turn, the wear intensity of friction units is determined by friction losses and heat liberation in them. Optimization of operation of interacting parts and extension of their service life are provided by supply of rational amount of lubricant. Existing calculation methods of oil supply systems are based on the determination of volumetric flows. It is known that in engines, transmissions and hydraulic drives of agricultural machines, the oil is saturated with gas bubbles and gets the physical and chemical properties that differ from the properties of pure oil. That has significant influence on friction losses and heat liberation and causes more intense wear. On the base of the developed mathematical models, the impact of gas bubbles contained in oil on its physical properties (density, viscosity) has been analyzed. The lubrication systems of engines and transmissions of agricultural machinery have been analyzed, their parameters have been determined, including the types of channels of force lubrication systems which significantly influence on the formation of two-phase gas-oil medium. The article proposes the computational dependencies of motion of two-phase gas-oil mixture through the channels of force lubrication systems, which allow to determine rational parameters of channels at the stage of machinery design. That allows to ensure the supply of necessary amount of lubricant for minimization of friction losses, maintaining the required thermal regime of parts and minimization of their wear. Application of suggested mathematical model will allow to decrease the amount of life tests.

New generation of transport and technological vehicles and agricultural transport means has been developed, based on the principle of design modularity with application of three-dimensional supporting systems of frame construction. Design decisions were implemented and introduced as the Ural-432065 all-wheel vehicle chassis with replaceable technological superstructures. A device for removing of replaceable technological superstructures from vehicle chassis and for their installing on support for storage was also developed. Three-dimensional supporting construction in the form of weld-fabricated steel pipe frame was selected. It was adapted for installation on technological superstructures and unified for bracketry on vehicle frame. Strength calculations were carried out. Sections of structural elements and method of their manufacturing were selected. Prototypes of devices were made on the basis of developed design documentation and installed on the superstructures: on the distributor of solid mineral fertilizers by means of threaded assembly; on the superstructure for hauling and subsoil fertilizing of liquid fertilizer organics by welding to load-carrying parts of the tanker. Computer simulation of the functional of replaceable technological superstructures allowed to estimate the efficiency of design decisions. Test results confirmed the data of analytical studies. Consequently, transport and process operations are implemented, both on open roads and in the field with satisfying of environmental and agrotechnical requirements. If there are several technological superstructures in the farm, it is possible to use only one vehicle chassis, which reduces the dead time and the impact of seasonality works factor.

The deterioration of soil properties as a result of repeated impact of undercarriage of tractor units leads to the reduction in crop yields. Increasing of soil density caused by the impact of movers of tractors and agricultural machines results in increase of soil hardness by 2-3 times. To forecast the indices of undercarriage impact on soil taking into account the type and condition of soil fertility, as well as to determine the promising ways of improvement of undercarriages’ designs and their agro-ecological characteristics, it is necessary to substantiate the regularities of accumulation of repeated soil settlements under the impact of undercarriage. It is also necessary to determine the regularity of rise of settlement deformer under repeated soil load. The deformation at each subsequent soil loading is followed by stress rise in the contact zone as compared to the previous one. This is due to the increase in load intensity under repeated deformations, in particular due to the reduction of contact area of wheels with soil during repeated passing of tracks. This paper observes some dependencies which allow to determine the deformation of soils with different physical and mechanical properties under various operating conditions and parameters of undercarriages of tractor units. For the soil with high degree of compaction, the depth of track should be reduced by increasing the number of axles of undercarriage. For the moist soil with low degree of compaction, the movers with larger width of wheels should be used to reduce the depth of track.