ISO 7902-3:2026

Overview

ISO 7902-3:2026 defines the permissible operational parameters of hydrodynamic plain journal bearings, specifically circular cylindrical bearings, under steady-state conditions. Developed by ISO, this standard provides empirical values for key operational limits relating to lubrication film thickness (h_lim), temperature (T_lim), and specific bearing load (p_lim). These values serve as a reference for designers, manufacturers, and maintenance professionals to ensure the reliable and efficient operation of plain bearings. The parameters specified may be adjusted based on manufacturer recommendations or specific application requirements. Reference is made to ISO 7902-1 for symbol definitions and calculation methods.

Key Topics

• Minimum Lubrication Film Thickness (h_lim)
  • Prescribes the least permissible thickness to prevent mixed friction and minimize wear.
  • Takes into account surface roughness, misalignment, and deflection.
  • Tables provided for empirical minimum values based on shaft diameter and velocity, assuming proper assembly, shaft quality, and lubrication.
• Effective and Maximum Permissible Waviness
  • Addresses surface deviations (waviness) impacting lubrication and wear.
  • Offers methods to determine the effective waviness and its permissible limits for operational reliability.
• Maximum Permissible Specific Bearing Load (p_lim)
  • Defines allowable bearing load primarily based on the bearing material group.
  • Ensures structural integrity and prevents deformation or cracking under mechanical stress.
• Maximum Permissible Bearing Temperature (T_lim)
  • Establishes limits depending on lubrication method and bearing material.
  • Aims to prevent material weakening and lubricant degradation under thermal load.
• Permissible Bearing Clearance
  • Provides recommended ranges for relative bearing clearance based on shaft diameter and operation speed.
  • Addresses factors influencing operational performance, such as temperature and mechanical deformation.

Applications

ISO 7902-3:2026 is widely applicable in fields requiring the use of hydrodynamic plain journal bearings, including:

• Industrial machinery: Ensures reliable operation of rotating equipment such as turbines, motors, pumps, and compressors by specifying safe operational limits for bearings.
• Automotive and transportation sectors: Provides guidelines for engine and axle bearings to maximize durability.
• Power generation: Supports the design and maintenance of generator and turbine bearings, where operational safety and uptime are critical.
• Heavy equipment: Enhances service life of bearings in construction, mining, and agricultural machinery by preventing wear and failures.
• Maintenance and quality assurance: Guides maintenance teams in assessing bearing condition and operational suitability during inspection and repair.

Related Standards

• ISO 7902-1:2026: Calculation procedures for hydrodynamic plain journal bearings, including symbol definitions and worked examples.
• ISO 286-2: Defines tolerance classes and deviations for holes and shafts.
• ISO 4381: Specifies tin casting alloys for multilayer plain bearings.
• ISO 4382-1 and ISO 4382-2: Outline requirements for cast and wrought copper alloys used in plain bearings.
• ISO 4383: Details multilayer materials for thin-walled plain bearings.

ISO 7902-3:2026 integrates seamlessly with these standards, supporting best practices in the design, operation, and maintenance of circular cylindrical plain journal bearings. Adhering to these operational limits helps achieve maximum reliability, efficiency, and longevity in bearing applications worldwide.