A Survey of Suspension Component Specifications and Vehicle Vibration Measurements in an Operational Railway System

Abstract

Primary and secondary suspensions are essential in railway vehicles. In this study, the specifications of suspension components were discussed in detail by referring to the component procurement documents to ensure satisfactory ride quality. These specifications were compared with those obtained from simulations and measurements of an operational railway system through a transverse vehicle model using the equations of motion derived from the Lagrange equation. The equivalent rail stiffness and damping were also derived. Results showed that the stiffness should be altered according to the vehicle’s load, i.e., the number of passengers on board. The secondary suspension stiffness could be determined based on the specification. The primary suspension stiffness was 26% higher than the upper limit of the specification with a load of full-seated passengers. According to the maintenance instructions, a 7-Hz low-pass filter (LPF) was used for car body vibration measurements. It is suggested that the cutoff frequency of the LPF had to be increased to 9 Hz at least for suspension defect diagnoses. Furthermore, a smartphone with a gravity sensor could also be used for measuring car body vibrations. A sampling rate of 100 Hz could obtain the desired results, which could be an effective and efficient method for vibration analyses.