Rolling bearing rating life L10 (ISO 281)
Basic rating life of a bearing in millions of revolutions and in operating hours from the dynamic load rating and the equivalent load, and the life at a higher reliability.
L_10 = (C / P)^pL_10h = 10⁶ · L_10 / (60 · n)L_nh = a_1 · L_10hL_10 is the life that 90 % of a group of identical bearings reach or exceed. The calculation follows ISO 281 for steel bearings; the modified life with the factor a_ISO (lubricant viscosity, contamination, fatigue limit) can be longer or shorter and is calculated by the manufacturer's method. For pumps, API 610 requires L_10h of at least 25 000 h at rated conditions.
Source: ISO 281:2007 (reliability factors a_1 per this edition); API 610 — bearing life of pumps
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
From the manufacturer's catalogue (C_r for radial bearings).
P = X · F_r + Y · F_a with X and Y from the catalogue; for a pure radial load P = F_r.
Unit converter for this formulaForce and load · Rotational speed · Time
- kN1
- N1,000
- MN0.001
- tf0.101972
- kgf101.972
- lbf224.809
- klbf (kip)0.224809
- L_10 — Basic rating life in revolutions–10⁶ rev
- L_nh — Life at the required reliability–
More in Drives and transmissions
Torque from the transmitted power and speed — for a motor, pump, gearbox or coupling — and the smallest diameter of a solid shaft for an allowable torsional stress.
Strokes per minute from the motor speed, the V-belt sheave diameters and the gearbox ratio, and the motor sheave diameter for a required stroke rate.
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.