Rolling Element Bearings
Many years of experience have shown that in practice, less than 10 % of all bearings will run for their design lifetime. About 40 % of bearing failures are attributed to improper lubrication, and about 30% of failures are from improper mounting, i.e. misalignment or "cocking". About 20 % fail for other reasons, such as overloading and manufacturing defects, etc.
These are the formulas for calculating the frequencies of the bearing tones from the bearing geometry, but they are a little imprecise because the axial loading and slippage affects them in an unpredictable manner.
The number of rollers in most bearings is usually between 8 and 12, but in very large diameter bearings, such as the ones found in paper machines, the number of rollers can be much higher.
Misaligned ("cocked") Rolling Element Bearings
Rolling Element Bearing Looseness
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