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In a heavy haul train operations the ruling grades that set the tractive power requirements for train consists are often associated with tight curvatures. Past studies of passive or active bogie steering developments have been mostly directed towards high-speed rail applications or light rail and commuter rail applications and hence studies have focused on two axle bogies. Linked passive steering three axle locomotive bogies such as produced by General Motors Electric Motor Division for the SD70 class locomotive are in widespread use however, there are few publications on traction and curving, and few papers on linked passive steering bogies. This paper presents a simulation study three axle bogie locomotives on various curve radii with traction and variable rail friction conditions. Curving performance is assessed showing body linked radial bogies to have considerable advantages over axle linked bogies that are significantly better than yaw relaxation bogies at improving steering under traction. As traction adhesion approaches the rail friction coefficient steering performance of all bogies without forced steering deteriorates to the same levels as a rigid bogie.

As heavy haul trains continue to push the limits of train size and mass and maximise locomotive performance, improving control of adhesion and slip will continue to be in demand. In considering the need to realise maximum adhesion forces for a rail vehicle, it is important to provide the development of new algorithms for traction control in a proper way that takes into account the need to avoid rail and track damage. This paper presents a strategy based on the Polach contact model for the detection of maximum adhesion force, and this strategy also includes slip compensation. The proposed traction control system has been verified by means of a co-simulation approach between the Gensys multibody code and the Simulink package.