Evaluation of current methods for extending the intervals between repairs of railway wheel sets

Abstract

The work is devoted to solving the urgent scientific and practical problem of evaluating and systematising modern methods for improving the operational reliability and extending the inter-repair mileage of railway wheel sets. It is substantiated that wheel sets are critical safety elements, accounting for about 10% of technical equipment failures, and that the processes in the wheel-rail system directly determine the level of resource conservation in transportation. The study analyses the dominant mechanisms of rolling surface degradation: contact fatigue, abrasive wear and thermal damage. Based on the study of domestic and foreign experience, methods for extending the service life have been systematised and classified into four main groups: structural, technological, operational and track maintenance methods. It has been established that among the design measures, the priority is the introduction of adaptive repair profiles (such as DMETI, ITM) with a non-linear generatrix. This ensures conformal contact, uniform load distribution and improved kinematic stability of movement. In terms of technological methods, the effectiveness of chemical-thermal treatment and plasma hardening has been assessed. It has been determined that the main quality criterion is the creation of a surface layer with an optimal balance of hardness and viscosity, as well as the formation of residual compressive stresses, which serve as a barrier to the development of fatigue cracks. Operational methods are considered in detail, among which forced lubrication of the ‘cam-rack’ zone demonstrates the highest efficiency, allowing the friction coefficient to be reduced to 0.08-0.12 and the wear intensity to be reduced by 2.5-4 times. The importance of the wheel set rotation strategy to compensate for uneven wear (the ridges of the running axle wear 40-60% faster) is substantiated. The impact of infrastructure is also emphasised: compliance with track width tolerances and preventive rail grinding can reduce wheel repair costs by 15-25%. Based on the results of the work, it is concluded that the maximum effect is achieved through the synergy of the methods considered. For freight traffic, a combination of ridge strengthening and lubrication is recommended, and for high-speed traffic, the use of adaptive profiles. A comprehensive approach allows for a 30-50% increase in the overall service life of wheel sets and minimises the life cycle cost of rolling stock.