The figure shows the frequency domain diagram of bearing 1 and bearing 3 when root crack and raceway fault occur simultaneously. The main frequency components in figure (a) are as follows: frequency domain 𝑓i (162.1hz) and its multiple frequency, the meshing frequency 𝑓m (570.4hz) of the fault gear and the interval is the sideband of the rotor frequency. The main frequency components in figure (b) are: frequency doubling of outer raceway fault frequency of bearing 3, inner raceway fault frequency of bearing 1 and meshing frequency of fault gear.