Non-linear stiffness analyzing of a hydraulic assisted turning system in low-floor trams

The paper is focused on investigating the stiffness characteristic of a hydraulic assisted turning system in low-floor trams. Equations to illustrate the operating processes of the simplified and the completed systems are presented respectively. Simulation works done in Matlab/Simulinkshow that the throttle valve and damping cylinder will reduce the stiffness of the system. The results also display that the system stiffness is related to the input signal and varies non-linearly. The model is verified with the dynamically outputting signals of the Simpack tram model. Researches accomplished in this paper will benefit to obtain an accurate analysis of tram´s dynamic characteristics and tuning principles of system´s stiffness.