Rolling-Bearing L10 Rating Life (ISO 281)
The cube law that punishes a bearing overload: L10 = (C/P)^p x 10^6 rev, L10h = L10 / (60 x rpm), with p = 3 for ball and 10/3 for roller bearings. A ball bearing (C = 5,000 lbf, P = 1,000 lbf, 1,750 rpm) lasts 125 million rev = 1,190 hr; a 25% overload to P = 1,250 lbf drops it to 64 million rev = 610 hr -- the cube law turns a 25% load increase into a 49% life loss, which is why a small alignment or belt-tension improvement pays off. Basic L10 assumes clean, well-lubricated operation (contamination needs the modified aISO life) and is the life at which 10% have failed, not the average. A planning estimate; the mounting, lubrication, and application govern.
Formula and source
p = 3 (ball) or 10/3 (roller); L10 = (C/P)^p x 10^6 rev; L10h = L10 / (60 x rpm).
The ISO 281 / ABMA 9 & 11 basic rating life (L10) of a rolling-element bearing, by name; the mounting, lubrication, and application govern.
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