The article is devoted to the issues of truck power unit operability and reliability provision during the service life. They considered the need for repair work at a certain moment corresponding to the maximum permissible values of part wear. The analysis of the technical condition of the cylinder-piston group parts of KAMAZ diesel engines was carried out and the main causes of malfunctions during operation were established. The dynamics of wear processes was studied taking into account the working processes of the engine, the material and the state of the part surface, the physicochemical properties of engine oil and diesel fuel. The authors have proposed an original approach to the issue of the repair action timeliness, based on the information about the indicators of the engine technical condition undergoing preventive measures and overhaul. The paper provides expressions to determine the criterion of the residual life, by which it is proposed to assess the rationality of the repair impact. Based on the analysis of the known methods of diesel engine part restoration, the expediency of surfacing and plasticization of cylinder liner surfaces is substantiated. The advantages and disadvantages of the selected repair method are considered. They provided the assessment of engine part restoration economic efficiency during repair.
The article considers the features of performing kinematic and power analysis of a controlled power mechanism for the transmission of wheeled transport and transport-technological machines. Such mechanisms are currently used mainly on cars in order to improve handling, stability, traction and dynamic properties in severe road conditions. Such mechanisms are not produced in Russia, but theoretical studies are currently being conducted, the results of which will allow determining the main parameters of the mechanism and synthesizing its kinematic scheme. The proposed approaches are based on the methods used in the kinematic and force analysis of planetary gears, but it is taken into account that the mechanism of power distribution during operation has two degrees of freedom. It is indicated that there is a structural and functional similarity between the power distribution mechanism of the car and the turning mechanism of the tracked vehicle. A method is proposed for calculating the gear ratio of the power distribution mechanism according to the condition of matching the minimum possible turning radius provided by the steering trapezoid kinematics and the calculated turning radius.
Over a long period of operation, under the influence of corrosion and stresses from the acting forces, metal structures lose their strength. There is a need for their periodic non-destructive testing. The development of new methods is relevant in the field of control of building metal structures, such as bridge structures, structures of building cranes and other mechanical engineering products. The applied methods should be reliable and should not require huge material and labor costs. In this work, informational relationships between acoustic characteristics and parameters of metal microstructure are established. The proposed method can be useful for specialists and experts in the field of monitoring the technical condition of metal products requiring non-destructive testing. The safety of the operated objects depends on the accuracy of the applied criteria, as well as the degree of resource saving due to the full use of the product resource.
The purpose of this work is to select a rational concept of the transmission of the tractor being created on the basis of an objective quantitative comprehensive assessment of the considered possible design options. The object of research is the transmission of wheeled tractors of 4 and 6-8 traction classes and forest machines based on their chassis. Making a decision on the principles of building a transmission is an important stage that requires a proper analysis of known theoretical developments, production experience, competitors’ achievements, market conditions and other factors. The decision is based on the ranking of the options available for implementation of the object. It is advisable to support such a ranking with the results of an objective quantitative comprehensive assessment of the compared options. The key points in this case are the formation of a nomenclature of objective private performance indicators and the choice of a data processing method. The paper considers the issue of applying the method of expert assessments when choosing the concept of constructing a transmission and the type of transforming mechanism of a tractor. The algorithm of the method, initial data, and evaluation results are presented. The main solutions for the construction of the transmission of tractors of 4 and 6-8 traction classes have been formulated.
A variant of the electromechanical transmission scheme for mobile platforms of small mass, designed primarily for operation in an organized artificial environment under the conditions of dimensional restrictions, is proposed. Typical examples of such environments are greenhouses, gardens and parks. Distinctive features of the proposed transmission are the use of a single traction motor and a power distribution mechanism that allows the use of two modes of side turn: in the range from a given minimum radius to infinity and turning around the center of gravity. The transmission scheme, with some changes, can be extended to mobile chassis of a larger mass - tractors of various traction classes, forestry machines, loaders, mobile robots, etc.
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