Gearbox mixed faults diagnosis under different working conditions based on meshing frequency modulation area

•Comparative study of vibration signatures for multiple gearbox faults.•Detection of Hunting tooth frequency and its modulation effect on the meshing frequency sidebands.•Original vibration signature for multiple gearbox tooth fault detection based on hunting tooth frequency and meshing frequency modulation effect. Condition monitoring of gearboxes is mainly based on vibration analysis. Traditionally, spectral lines related to shaft speeds and gear meshing frequency (GMF) are the key components that serve as fault indicators. However, due to the noise level and the dependence of signal energy on operating conditions, this technique can fail. In this article, we present an alternative technique based on the calculation of the area covered by a spectral band around the GMF. This band is observed in the envelope spectrum of the vibration data and covers the modulating components characterizing the appearance of the defects. The experimental results obtained from a gearbox test bench operating under different speeds and load levels show the effectiveness of the proposed fault indicator in the detection of combined faults. Compared to certain other known methods for diagnosing gear faults, the proposed technique shows its superiority in terms of processing time and simplicity of implementation.