ISO 17956:2025

Rolling bearings — Method for calculating the effective static safety factor for universally loaded rolling bearings

Scope

This document specifies the calculation of the effective static safety factor under consideration of tilt or misalignment, operating clearance of the bearing, and internal load distribution on rolling elements. The calculation method provided in this document covers influencing parameters in addition to those described in ISO 76.
The directions and limitations given in ISO 76 and ISO 20056-2 apply to this document. The calculation method pertains to the static safety factor of the bearings. Other mechanisms of failure, like false brinelling, fatigue life, wear or microspalling (gray-staining), lie outside the scope of this document.
This document applies to single and multi-row radial and thrust ball and roller bearings, subjected to radial and axial load and with radial clearance and tilt taken into account. References to methods for the analysis of the internal load distribution under general load are given.
The analysis of effective static safety factor for multi-row bearings or bearings of a more complex geometry can be derived from the formulae given in this document. For these bearings, the load distribution for each individual row is considered.
The calculation of effective static safety factor is also applicable to hybrid bearings, using the static load ratings according to ISO 20056-2.