ISO/TR 25269:2026

Rolling bearings — Calculation of theoretical reliability

Scope

This document contains information on the reliability analysis for rolling bearings. The method described only pertains to the fatigue life per ISO 281 or ISO 16281 of rolling bearings. Other mechanisms of failure, like wear, microspalling (gray-staining) or white etching cracks (WEC), lie outside the scope of this document.
A multi-row rolling bearing is considered as a single rolling bearing in the context of this document.
The method is based on the life analysis per ISO 281 or ISO 16281, thus the general directions and limitations given in these documents apply.
The calculated theoretical reliability is not suitable as the only criterion to select or optimize a rolling bearing or rolling bearing arrangements in powertrains, because the actual bearing reliability in service is also dependent on minimum load, rolling element slip, lubricant and lubricant supply, and heat dissipation.
The calculated theoretical reliability does not replace or substitute any safety factors used for consideration of uncertainties in load assumptions, e.g. operation factors for shock loads.