HORBUNOV Nykolai, KOVTANETS’ Maksim, NOZHENKO Elena & KOVTANETS’ Tatiana
At present, rail transport in connection with the economic situation is very important for solving the problems associated with increasing the efficiency and economy of the railway transport. It is necessary to modernize not only the infrastructure, but also locomotives and other railway equipment.
It is proposed for the most rational use of air from brake cylinders, which, after release of the brakes, is vented into the atmosphere, passed through the Rank-Hilsh vortex tube, and by means of a flexible hose system to be sent to the friction zones requiring cold (in the contact area of the brake pad and wheel or brake pad and brake disc while braking) or hot air (to the contact area of the wheel with the rail when started).
It is established that when the compressed hot air is fed into the contact area of the wheel with the rail, the drying from the moisture and the cleaning of the zone of friction contact from the "third body" occurs. Such a technical solution will reduce the wear of the wheels of the locomotive and rails, reduce the consumption of equipment and eliminate clogging of the ballast prism. In this case, the coupling properties of the surfaces of the wheels and rails will be increased due to their preliminary heating and cleaning from the unfavorable "third body". Excessive heat emission leads to a decrease in the strength of the surface layers, the destruction of the binder in the composite materials of brake pads locomotives, thermal stresses, the dissociation of adsorbed films on the metal. The analysis of the temperature curves of the friction characteristics and of the physical and mechanical properties of steels shows that at a temperature of 350 ° C there is a decrease in the values of tangential stresses and the coefficient of friction, but with increasing this temperature, the diffusion mobility of the atoms and the tendency of the steels to grip increase. The achievement of the surface temperature in a local contact over 450 ° C leads to a significant deterioration of the mechanical properties of the interacting surfaces, which leads to a decrease in the frictional force and their intense wear of the contact surfaces. The authors of the work propose the control of the process of frictional interaction of the contact by controlling the temperature by forced cooling, which will stabilize the coefficient of adhesion
he principle of using compressed air from brake cylinders, which is fed into the atmosphere during braking, is proposed to improve the coupling properties of friction surfaces when moving and braking. It has been established that by selecting rational structural parameters of the Ranka-Hilsha tube and the basic parameters of the flow of compressed air at the inlet, it is possible to control the temperature in the zone of the tribological contact, creating conditions for controlling the clutch process, and the forced maintenance of the constant of the temperature in the contact leads to stabilization of the coefficient of adhesion at the maximum level, providing optimal contact conditions. The work contains studies that were conducted within the framework of the state budget project DN-01-17, funded by the Ministry of Education and Science of Ukraine.
Keywords: rail transport, coefficient of friction, Rank-Hilsh tube, temperature