A locomotive’s dynamic response to in-service parameter variations of its hydraulic yaw damper

An improved hydraulic yaw damper model with series in-service clearance and comprehensive stiffness was proposed by Wang et al. (Nonlinear Dyn 65(1–2):13–34 2011). In order to study how in-service parameter variations to the hydraulic yaw damper affect the dynamics of a Chinese $$\hbox {SS}_{9}$$SS9 locomotive, this study continued that research by establishing a multibody system (MBS) model of the $$\hbox {SS}_{9}$$SS9 locomotive–rail coupling system, and then validating the MBS model using field test data from the $$\hbox {SS}_{9}$$SS9. Extensive simulations were performed, and the results demonstrated that both the effective stiffness and the small clearance accumulated between two ends of the damper due to wear and lack of maintenance had remarkable impacts on the locomotive’s critical speed and on its normal operation. The results also influenced the locomotive’s ride comfort, but the effect of the small clearance was more remarkable than that of the effective stiffness in this regard, and these parameters had little to no influence on the locomotive’s curve-negotiation performance. The small clearance and effective stiffness are usually omitted or simplified in engineering, and so it was important to apply the proposed in-service nonlinear damper model with series clearance and stiffness to a vehicle dynamics study and improve the accuracy of vehicle design. The study was also useful for setting pertinent vehicle maintenance standards in engineering to control the influence of such in-service parameter variations.