Gear reducer is a very important gear transmission product, and gear transmission is one of the main forms of mechanical transmission. At present, gear reducers are widely used in industrial sectors such as metallurgy, petrochemical, mining, transportation and so on. However, due to the material of the gear itself, the workmanship, and the working environment, it is easy to be damaged and malfunction. 80% of the failure of the gear reducer is caused by the gear. The failure of the gear will directly affect the safe and reliable operation of the gear reducer, and even lead to the paralysis of the entire equipment. Therefore, the monitoring of the working state of the gear and the research of fault diagnosis technology have received more and more attention.

There are various failure modes of gears. The more common crack failure is a serious failure mode. The crack further expands, which may cause the gear teeth to break and even cause complete failure of the entire gear. Therefore, it is very important to analyze the fault mechanism of cracks and find an effective method to diagnose crack faults.

With the use of gear reducers becoming wider and wider, and the time is getting longer, people have done a lot of research on the diagnosis method of tooth root cracks, and have achieved many results. The conventional diagnostic method is vibration spectrum analysis. It is based on the traditional vibration theory. The diagnostic instrument is used to collect the vibration data and waveform, and then analyze and diagnose to find out the cause and location of the fault. However, the precondition for this is that the fault model must be established accurately enough to correctly identify the vibration signal in the fault state. This method requires the diagnostic personnel to have rich experience in fault diagnosis.