Based on the research of a technique of time domain averaging and the theory and the experiment of time and frequency domains entropy of Hilbert-Huang transformation

the vibration signals of the horizontal gear box in a working rolling mill are measured.The signals are pretreated by using the technique of time domain averaging

the entropies of Hilbert-Huang transformation is calculated.They are used as fault feature when the fault of the horizontal gear box is diagnosed.It brought forth a good fruit and confirmed that the method is advanced

reliable and practical.A new method is provided for fault diagnosis of the horizontal gear box in a rolling mill.