A Study on the Effect of Running Vibration Caused by Suspension Stiffness Changes of Subway Vehicles

A suspension system of subway vehicles is composed of 1 st. and 2 nd. spring. The suspension system is the most important parameter of running vibration. Application of the 1 st. suspension with a strong stiffness is the main design direction in order to improve the running performance at a high speed, but it causes severe vibration problems of the vehicle. In this paper, it was studied how much the stiffness changes of the 1 st. suspension in EMU(Line 5), which consists of chevron rubber springs, has effects on the vibration of the subway vehicle. We measured the chevron rubber spring stiffness and the vibration of the subway vehicle. We found out that if 35% (0.7kN/mm) of the vertical stiffness exceeded over the standard vertical spring stiffness (2.0kN/mm), the maximum vibration acceleration to the vertical and lateral directions increased by 0.045g (58%) and 0.008g(10%), respectively.