Modern methods of modifying the frictional state of the wheel-rail system

Abstract

The paper analyzes and provides a systematization of possible methods for increasing the coefficient of adhesion of locomotive wheels to rails. Ensuring a rational value of the friction coefficient at the point of contact between the wheel and the rail makes it possible to reduce the energy consumption for traction, significantly reduce the wear of the wheel and rail rolling surface when passing the curved sections of the railway track, and increase the smoothness of the carriage and its safety during braking. Two fundamentally different methods of improving the locomotive traction qualities have been established - by means of structural improvements of the carriage and a direct effect on the physicochemical properties of the wheel and rail contacting surfaces. Practical methods of increasing the value of the friction coefficient in the contact between the wheel and the rail which include the use of sand, materials of natural origin, abrasive magnetic powder, braking of moving wheels, mechanical cleaning of rails, chemical cleaning of rails, electric spark cleaning of rails, plasma cleaning of rails, cleaning with high-energy sources, cleaning with high-energy sources, transmission of electric current and magnetic flux in the contact zone, the use of various modifiers of friction surfaces, are considered in detail. Their main advantages and disadvantages are noted. It is established that when wheels friction is on rails, mechanical, electrical, vibration, thermal, chemical, and magnetic processes occur simultaneously. In view of this, the practical implementation of a multivariate analysis of the entire complex of these phenomena is in most cases impossible. In this connection, it is suggested to be limited to a small set of factors that could most fully characterize the tribological system under study and determine the basic requirements for the experimental and theoretical studies.