Influence of Self-steering Axles on the Directional Response of Commercial Vehicles

Application of self-steering axles to heavy vehicles in an effort to decrease tire wear and increase low-speed maneuverability has the potential to degrade the high-speed directional stability of the vehicle. This degradation comes from the axle developing a steer angle in response to lateral force or aligning torque in such a way as to reduce tire slip angle and thus reduce the lateral force generated at the steerable axle. The effect of replacing a fixed axle with one that possesses a passive self-steering mechanism is investigated analytically using a computer simulation. Variations in parameters of the steering mechanism itself and in the axle location on the vehicle are examined to evaluate their influence on both high- and low-speed maneuvering.