The current work focuses into two main directions ofrotor dynamics object: the simulation ofa rotor-bearing system and the detection of defectsthat are commonly appeared in rotating systems. Thetransverse breathing crack in a rotor and the radialyextended wear in a bearing are the defects presentedin the simulations. The persuasion is initialy tomake a proposal in rotor-bearing system nonlinearsimulation and secondly to suggest methods able todetect the transverse breathing rotor crack and thebearing wear. Time-frequency analysis is performedusing continuous wavelet transform in numerical andexperimental time histories in order to extract thevariable coupling phenomenon exclusively due to thebreathing crack from the other two main reasons ofcoupling, the bearings and the shaft. The mainspeculations are that both defects have to bedetected in an early growth and without the demand ofinterrupting the operation of the system since thiscannot be always feasible in real rotating machinery.The growths of the defects have to be at least of 10%of rotor radius for the crack, and 20% of bearingradial clearance for bearing wear.