Design of a test rig for railway Axle-boxes

Railway axle-boxes are one of the more critical components of the railway vehicle. The axle-box is the housing of the bearings, which support the axle-load of the vehicle, and the confinement of the lubricant required to maintain the performances of the bearings. Therefore, the axle-box is involved both in problems related to vehicle safety, and in problems related to maintenance, becoming an important part of the life cycle cost of the vehicle. To improve safety and reliability of the axle-box, in recent years, diagnostic systems are adopted to detect malfunctions, damage or degradation of the performances of the bearings. This is made both using onboard or wayside monitoring systems, which can be based on vibration or thermal analysis. The effectiveness of these systems rely in the accuracy of the algorithms, that are used to predict the condition status of the bearings. Therefore, it is necessary to be able to validate and tune the algorithms, by means of experimental tests. The tests can be performed on the track, but this implies high variability, costs and the impossibility to experience critical conditions (due to the related risks). The aim of this work is to design an experimental test rig, able to perform tests on railway axle-boxes and to reproduce the real conditions (axle-load, velocity). Several design layout are considered, each one evidencing some benefits and some limitations. The use of the test rig allows to reproduce different failures of the bearings in a safe environment. The repeatability of the tests and the controlled environmental conditions, allow a better setup of the monitoring system being developed.