DEVELOPING A SINGLE-AXLE STEERING BOGIE USING REAR-AXLE CREEP FORCE

Railway vehicles negotiating sharp curves are subjected to significant lateral forces and high derailment coefficients. The derailment coefficient, defined as the ratio of the lateral force acting on a wheel to its vertical load, is a critical indicator of operational safety. At such curves, wheel flanges come into contact with the gauge corner of the outer rail, leading to increased wheel–rail interaction. To improve curve-negotiation performance, Wickens proposed a theory of steering based on the yaw angles of the leading and trailing wheelsets [1]. Steering bogies based on this theory have already been put into practical use [2,3]. To extend Wickens’ theory, this study investigated a novel steering method that focuses on the yaw angles of the wheelsets and the bogie frame. Based on the concept of rear-axle steering, a novel steering bogie was developed to improve curve-negotiation performance by accounting for the wheel–rail contact position. Rear-axle steering effectively reduced the lateral force acting on the outer rail and the attack angle of the leading wheelset. A dual-axle steering bogie that steers both front and rear wheelsets was also developed. The performance of the dual-axle steering bogie was evaluated based on onboard measurements. The steering rate of the bogie was higher than that of the single-axle steering bogie, with further improvements in wheelset posture and curve-negotiation performance across all curve radii. The performance improvements were verified via field tests. The results of this study can support mass production of the rear-axle steering bogie.