Bearing failure is one of the most common faults in industrial machines. Proper condition monitoring is therefore of the highest importance. There are two main groups of bearing types:
1. REB covers the whole family of Roller and Ball bearings, and the monitoring method is similar for Radial bearings of both types. The condition monitoring is normally done with one radial accelerometer and the use of some special measurement techniques with envelope detection as most important. REBs with thrust loads need additional measurements in the axial direction
2. Journal and plain bearings are in general tight-fitting cylinders, which encompass a shaft with some lubrication in between. The plane bearings are monitored with vibration, temperature and oil pressure as the most important parameters. Bigger radial bearings are normally monitored with a pair of displacement sensors, in order to measure shaft position, and shaft orbit and spectra are the major part of the vibration monitoring task.