Slewing bearing is an important part of the machinery industry. It is a mechanical force transmission element that the upper and lower parts need to do relative rotation movement. It can bear radial load, axial load and overturning torque at the same time. It is called "machine joint". In hydraulic excavator, slewing bearing is also one of the most vulnerable parts. When the upper slewing body of hydraulic excavator can not rotate, there is noise in the process of rotation, or the bucket swings at the end of rotation, these may be caused by the failure of slewing bearing.
