A study on the wear allowance of a railway vehicle hydraulic damper

Abstract

Railway vehicle hydraulic dampers are usually subject to wear-induced premature failures, so it is meaningful to evaluate the wear allowance of the hydraulic damper. Mathematical modelling of damping characteristics of a railway vehicle hydraulic damper under wear conditions is carried out, the model describes the functions of main damping characteristics indices vs. inner tube wear M1 and rod wear M2 . Simulation is then performed using the model, and indicates that increase of M1 would lead to significant drop of the maximum extension damping force, fading of the damping coefficient and significant rising of the damping force asymmetry rate, but the maximum compression damping force keeps to be constant, while increase of M2 would lead to significant drop of almost all of the indices except for the asymmetry rate. A wear allowance line for the damper is finally obtained when both of M1 and M2 work in real situations, the area enclosed by the wear allowance line and two axles is a safe area, any dot with a combination of M1 and M2 outside the safe area means the damper has exceeded its wear allowance and should be maintained or replaced. The mathematical model and the wear allowance line obtained in this work can be used for health status evaluation and design optimization of railway hydraulic dampers.