ROLLING BEARINGS (ISO 281 L10)

Rolling-element bearing fatigue life follows the L10 model: 90% of identical bearings under identical load survive at least L10 hours. L10 = (C/P)^p · 10^6 / (60·n) where C is dynamic load rating, P is equivalent load, n is rpm, and p = 3 for ball bearings, 10/3 for roller. For combined radial and axial loading, P = X·Fr + Y·Fa with X and Y from manufacturer tables based on Fa/Fr ratio.

• L10 = (C / P)ᵖ
• p = 3 (ball), 10/3 (roller)
• L10h = L10 · 10⁶ / (60·n) hours
• P = X·Fr + Y·Fa
• L_na = a1·a23·L10 (modified)

References & StandardsISO 281, ISO 76 (static), SKF/FAG/Timken catalogs

Pick bearings for any rotating equipment: motors, gearboxes, conveyors, machine spindles. Compute equivalent load from external forces, look up dynamic capacity from a bearing catalog, and verify L10 against the design service life (commonly 20,000-50,000 hours for industrial). For lightly loaded bearings, use the static capacity rating instead. Adjust L10 for reliability (L5, L1) using the modified rating-life equation.