Identification of Bearing and Gear Tooth Damage in a Transmission System

The main objective of this article is to identify individual and combined damages in gear teeth and rolling element bearings based on vibration signatures. In this study, experimental vibration signals generated from a 75-HP test facility are used for the comparative studies. Vibration signatures from cases with no gear tooth or rolling element bearing damage (baseline healthy machine), preset gear tooth damage only, preset rolling element bearing damage only, and preset damages in both gear tooth and rolling element bearing system are examined. The vibration signatures obtained are compared in the original time domain, the frequency domain using the fast Fourier transform (FFT), the joint time-frequency domain using the Wigner-Ville distribution (WVD), and the statistical representations of the chaotic vibrations using the modified Poincare maps. Based on the results of this comparative study, special features in the vibration signatures for each type of damage are identified and categorized. Using the categorized results, general conclusions are drawn concerning the identification of both individual and combined gear tooth and rolling element bearing damages.