Experimental Characterization and Modelling of a Side Buffer for Freight Trains

Abstract

A detailed investigation performed by European Rail Research Institute (ERRI) relevant to the safe running of heavy freight trains revealed how levels of buffer forces exceeding 240 kN can deeply reduce the safety margins of a train-set. Even if the analysis pointed out the role played by buffers in affecting running safety, little is known about their response; according to the UIC 526-1, buffers mounted on freight trains should satisfy general requirements in terms of stored and dissipated energy under quasi-static load cycles and during impacts between adjacent vehicles at given relative speeds. This work aims at characterizing the buffer response under working conditions close to the ones experienced during critical manoeuvres like braking while cornering or when passing over switches. A special test bench was thus set up to impose static and dynamics loads on a buffer through hydraulic actuators, considering also misaligned axial forces and the application of tangential forces reproducing the effect of friction between adjacent buffers; data collected through experimentation were then used to develop a complex rheological model of the component. The model of buffer was eventually introduced into a simulation code to investigate the effect of its response on the train-set dynamics.