General tolerance guideline for dis

General tolerance guideline for displacements and gaps is provided for the two bearings per rotor system (45° lines) and shared bearing systems (hatched area) as illustrated in Fig. 6.15. As can be seen, tighter tolerances are recommended for shared bearing rotor systems because they become very sensitive even with minor shaft misalignments. A coupling misalignment can easily be diagnosed using vibration and bearing metal temperature data for a two bearing per rotor system. As discussed before, a misaligned coupling on a shared bearing system could trigger vibration in a rotor located at two or three spans away. Therefore, it becomes a challenge sometimes to diagnose the symptoms of vibration for the shared bearing rotor systems. Consequently, it is highly recommended to always maintain tighter tolerances for shared bearing rotor systems