Simulation of traction curving for active yaw — force steered bogies in locomotives

Abstract

Steering bogies and actively steered bogies are subjected to increasing interest. Self-steering bogies have been used in large numbers of hauling locomotives primarily in the USA to reduce flange wear and improve adhesion. However, the steering performance of self-steering bogies is reported to deteriorate under traction. This article compares several bogie types and proposes a new design of steering bogie featuring forced steering combined with control of the bogie yaw movement or actuated yaw forced steered bogie (AY-FS). The bogie stability of a force steered bogie is improved by yaw actuation using a negative derivative control of the bogie yaw misalignment. An additional benefit of the bogie design is that actuators and control sensors for the AY-FS bogie can be mounted on the vehicle body rather than on the bogie frame. The article presents simulation results for a yaw actuated force steered bogie under traction curving conditions. The AY-FS bogie is compared with rigid and force steered bogies and is shown to give superior performance at high traction adhesion levels during curving. The curving performance improvements achieved depend on the curvature, lateral forces on the vehicle, the traction load, and the rail friction. The greatest curving performance advantages occur in tighter curvatures with high traction loads and low rail friction and with high lateral forces to the inside rail such as would result from coupler loads on pulling locomotives.