Effect of Load on Vibrations of a Railway Gearbox

Condition monitoring of a railway gearbox installed on a metro vehicle is described. The peculiarities of the application, which led to a sort of "bouncing" of the whole gearbox when running in coasting at high speed, are such that extensive failures of the cage of a taper roller bearing were observed and related to the abnormal accelerations measured on the casing. The complexity of the signals led to the need to use numerical indicators more sophisticated than levels or energy. A proper combination of different indicators was checked during tests in different conditions and verified through the application of the procedure to signals from regular service. A combination of energy and kurtosis was found to give the best results in terms of reliability of detection.