It may be obvious that excessive loads are a problem, but it is not so obvious that insufficient loads can lead to failures of certain bearing designs as well. Bearings that are lightly loaded can lead to a form of sub-synchronous rotor vibration called oil whirl (or oil whip). The amplitudes of this type of vibration can be very large, approaching the full-bore clearance of the bearing. Such large amplitude vibrations at fractional frequencies develop high pressure fluctuations in the oil film, and this phenomenon leads journal to bearing contact, to broken Babbitt, to Babbitt wipes, and ultimately, to bearing failure. Read More…
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