Most research on the vehicle dynamics of railway locomotives has currently been conducted in multi-body software packages with purely mechanical systems. Consequently little information is available regarding the simulation of locomotives as mechatronic systems that are capable of modelling traction and braking capabilities, along with the use of coupler forces from longitudinal train simulation to provide more detailed results. This paper discusses a methodology for the modelling of locomotives as complex systems in order to evaluate the effects of lateral coupler forces on locomotive wheel-rail forces when under traction in corners, with a focus on Australian railways. Longitudinal train simulation is used to help generate lateral coupler forces for use with multi-body locomotive models that contain simplified traction control algorithms and have been tested using a Locomotive Model Acceptance Procedure. Differences in locomotive traction control systems and bogie types are also considered.