The paper substantiates an approach to assess a probability of electric equipment combustion in passenger cars. The method proposed is based on monitoring of parameters connected with physical processes that lead to combustion, and allows eliminating a human factor as a source of fire hazard from the consideration.

The paper is devoted to modeling of nonstationary field of a passenger car wheel at braking. The calculation is based on formulation of thermal conductivity equation for the wheel tread as a curved rod with the application of linear approximation of thermal field. At formulation of thermal conductivity equation it is necessary to consider a balance of heat in small volume of tread with the consideration for thermal flow from braking shoe, thermal emission to the environment and thermal conductivity in circular direction. The authors have set for the initial equation of thermal conductivity a functional and have formulated conditions of stationarity that leads after integration to the system of the first order differential equations of time. The authors have applied the Euler method at integration. The developed method has been realized in the C++ program. With the use of this application the authors have conducted a research of the thermal field of the passenger car wheel. The method can be used at designing of new rolling stock and for the analysis of reasons of flaws appearance on the surface of car wheels.

The paper is devoted to optimization of maintenance and repair system of passenger cars. The method is based on the use of profitability as a criterion of optimization. Revenue from car operation is supposed to be uniform during a service life. Costs include price of construction, expanses on utilization (with deduction of income from the writeoff), expanses on repairs of large volume, expanses of other railway services and variable expanses on current maintenance of a car in inter-repair periods that are assumed to change linearly and quadratically during each inter-repair period. The authors propose a method to consider dependence of current repairs cost on a car condition during its life cycle. They also have developed a method of optimization of costs on roundhouse servicing and major overhaul. The proposed methods are realised on C++ language in the form of software package that can be used to control the passenger car repair system and for development of new cars.

The work objective is to develop a mathematical model of the force characteristics of shock absorbers based on viscous friction, including elastomeric ones. For this purpose, the following tasks are solved in the work: the existing approaches to the mathematical modelling of hydraulic shock absorbers are analysed, a mathematical model based on hydraulic equations (the Darcy–Weisbach equation) is proposed, the developed mathematical model is verified and the results are compared with the results obtained based on the existing approach. Research methods: the equation of fluid flow through holes with hydraulic friction; D'Alembert's principle for composing the equation of car swaying motions; the Euler method for numerical integration of the differential equation. The novelty of the work consists in the fact that a mathematical model of the power characteristics of shock absorbers with viscous friction is proposed, based on the quadratic dependence of the reaction on the deformation rate. The results are the study of car swaying motions based on the traditional and proposed approaches. The proposed mathematical models can be used to develop shock absorbers with improved characteristics when designing passenger cars.

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