ISO 7902-2:2020

Overview

ISO 7902-2:2020 is Part 2 of the ISO 7902 series for hydrodynamic plain journal bearings. It specifies the numerical values of the basic functions used in the calculation procedure for oil‑lubricated, circular cylindrical hydrodynamic bearings operating under steady‑state and full‑lubrication conditions. The document provides tables, graphs and formulae that support the calculation procedure described in ISO 7902-1 and uses the assumptions and boundary conditions given in that Part 1.

Key topics and technical content

• Tables of basic bearing characteristics (Tables 1–30) - tabulated values for multiple configurations (angular span Ω, relative bearing width B/D) and eccentricities ε. Key tabulated quantities include:
  • Attitude angle (β)
  • Sommerfeld number (So)
  • Specific coefficients of friction (loaded area f/φ and accounting for unloaded area f′/φ)
  • Lubricant flow rate coefficient (Q3) due to internal pressure generation
• Graphs of basic bearing characteristics - graphical forms of the tabulated functions for design and interpolation.
• Friction power loss - methods and values used to estimate power dissipation in the lubricant film.
• Lubricant flow rate from feed pressure - calculated for multiple feed geometries (see sections):
  • lubrication hole opposite to load, holes at 90°, pairs of holes, circumferential grooves (full and partial), lubrication pockets (single and pairs)
• Effective dynamic viscosity (ηeff) - relationship between effective lubricant viscosity and effective bearing temperature.
• Provided calculation support: values can be obtained from tables, graphs or formulae; symbol descriptions and worked calculation examples are referenced in ISO 7902-1.

Practical applications and users

ISO 7902-2:2020 is intended for:

• Bearing designers and mechanical engineers performing bearing calculation and sizing
• Tribology engineers predicting frictional losses and lubricant flow
• Rotating‑machinery designers for turbines, compressors, pumps, electric machines and machine tools who need validated bearing characteristic data
• Maintenance and reliability engineers evaluating bearing performance under steady operation

Using this standard helps ensure consistent, reproducible calculations for hydrodynamic journal bearings and supports selection of bearing geometry, lubricant specifications and feed/groove arrangements.

Related standards

• ISO 7902-1 - Hydrodynamic plain journal bearings - Part 1: Calculation procedure (symbols, assumptions and worked examples)
• Other parts of the ISO 7902 series addressing additional geometries or conditions (refer to ISO catalogue)

Keywords: ISO 7902-2:2020, hydrodynamic plain journal bearings, circular cylindrical bearings, bearing calculation, Sommerfeld number, friction power loss, lubricant flow rate, effective dynamic viscosity, ISO 7902-1.