Glossary
Basic rating life L10
Nominelle Lebensdauer L10
The basic rating life L10 is the number of revolutions — or operating hours L10h at constant speed — that 90 percent of a sufficiently large group of identical bearings will reach or exceed before the first signs of material fatigue. Per ISO 281 it is calculated as L10 = (C/P)^p, with life exponent p = 3 for ball bearings and p = 10/3 for roller bearings.
L10 is a statistical value; an individual bearing may fail much earlier or later. The modified rating life additionally accounts for lubrication, cleanliness and the fatigue load limit. Bearings that consistently fail far short of L10 usually suffer from lubrication, mounting or contamination problems, not fatigue.