ISO 76:2006

Overview

ISO 76:2006 - Rolling bearings - Static load ratings - defines standardized methods to calculate the basic static load rating and the static equivalent load for rolling bearings. It covers ball and roller bearings within the size ranges of relevant ISO bearing standards, manufactured from commonly used hardened bearing steel and of conventional contact geometry. The standard links calculated load ratings to tolerable permanent deformation and gives guidelines for static safety factors for heavily loaded applications.

Keywords: ISO 76:2006, static load rating, rolling bearings, basic static load rating, static equivalent load, static safety factor

Key topics and technical requirements

• Scope and applicability
  • Methods apply to conventional ball and roller bearings made from standard hardened bearing steels.
  • Not suitable when contact areas are truncated or load distribution deviates significantly (e.g., severe misalignment, large preloads/clearances, special coatings). In such cases the user should consult the bearing manufacturer.
  • Not applicable where rolling elements run directly on shaft/housing surfaces unless those surfaces are fully equivalent to bearing raceways.
• Definitions and symbols
  • Standardizes terms (static load, basic static radial/axial load rating, static equivalent load, static safety factor) and symbols used in calculations.
• Calculation methods
  • Provides equations and tables to compute basic static radial and axial load ratings and static equivalent loads for:
    • Radial ball bearings (including single-row, paired and tandem arrangements)
    • Thrust ball bearings
    • Radial roller bearings
    • Thrust roller bearings
  • Example: factors (f) and geometric parameters (number of rolling elements Z, pitch diameter D, contact angle α, etc.) are used to derive the basic static radial load rating.
• Contact stress basis
  • Load ratings are based on contact stress levels associated with a small permanent deformation (~0.0001 of rolling element diameter):
    • 4 600 MPa for self-aligning ball bearings
    • 4 200 MPa for other ball bearings
    • 4 000 MPa for roller bearings
• Static safety factors
  • Guidance on selecting a static safety factor (ratio of basic static load rating to static equivalent load) for heavy or safety-critical load cases.

Applications and who uses it

• Engineers and designers calculating bearing suitability for static or low-speed, heavily loaded installations.
• Bearing manufacturers for rating and data-sheet generation.
• Maintenance, reliability and condition-monitoring teams assessing risk of permanent deformation in bearings under static loads.
• Machinery OEMs specifying bearings for gearboxes, wind-turbine bearings, marine equipment, presses and other heavy static-load applications.

Related standards

• ISO 5593 - Rolling bearings - Vocabulary
• ISO 15241 - Rolling bearings - Symbols for quantities
• ISO/TR 10657 - Explanatory notes on ISO 76

Use ISO 76:2006 together with bearing manufacturer guidance when application conditions deviate from the standard assumptions to ensure accurate static load evaluation and safe bearing selection.