Friction Management and Top of Rail Lubrication

The rolling motion of a steel wheel on a steel rail is a complex issue where static and dynamic forces act simultaneously. Various factors and parameters are interrelated for the wheel-rail interface mechanism. Researchers and scientists are working on this area to achieve better outcomes. For effective rail operation, lubricant is applied on the wheel flange-rail gauge interface to reduce wheelrail wear on curved track. While this cannot effectively control curve squeal, flanging noises, adhesion problems etc., it has been found that application of friction modifiers at wheel-rail interfaces in sharp curves can manage the wheel guiding and curving forces, and stick/slip oscillation of the wheel-rail contact patch. The latter can also minimise noise and wheel squeal, lateral and longitudinal creep forces in curved sections and ultimately result in reduced wheel-rail wear, RCF, corrugation etc. In the long run, Top of Rail (TOR) friction management has a positive impact with regard to energy savings, increasing asset life and reduction of rail grinding losses. A wide variety of engineering approaches have been adopted for increasing the axle load to achieve optimal operating conditions. In Australia, the heaviest train systems are used for bulk ore transportation. TOR friction management techniques are being used in some of the North American heavy haul rail networks with beneficial results. In Australia, there has been limited use of top of rail lubrication, mainly applied to improve steering forces and mitigate wheel squeal. Engineering analysis and numerical modelling was undertaken in this research for studying wheel-rail interactive forces, tangential creep forces and their behaviour under various operating conditions with predefined frictional states. The simulations were run in the GENSYS environment (a rail vehicle dynamic simulation package) considering train operating practices and wagon-track input data in compliance with known characteristics of an Australian heavy haul rail network. The simulation outcomes considering two sharp curvatures (200m and 400m radii) have been further assessed for both high and low rail head loss in respect of wear indices. A life cycle cost analysis has been conducted based on rail grinding frequency and the resulting enhancement of rail life. This research project seeks a xviii holistic understanding regarding top of rail lubrication and management of wheel rail friction in the Australian context. It is evident from the simulation outcomes and engineering analysis that TOR friction management along with effective curve lubrication in heavy haul networks can significantly improve the curving performance of the vehicles as well as reduce the rate of head loss of the rails in the curved track. The TOR friction management improves the rail service life. From the undiscounted cost-benefit analysis, the cost saving was estimated to be a minimum of 22% and up to 46% depending on the operating conditions. The findings of this work can be extended for further simulation on various working conditions such as worn wheel-rail profiles, distributed power configurations for long trains, different track properties and impact forces etc.