ISO/TS 31657-1:2020

Overview

ISO/TS 31657-1:2020 - Plain bearings - Hydrodynamic plain journal bearings under steady‑state conditions - Part 1: Calculation of multi‑lobed and tilting pad journal bearings provides an easy‑to‑use, practical calculation procedure for hydrodynamic plain journal bearings. The technical specification defines the general principles, assumptions and preconditions for predicting the approximate performance of multi‑lobed and tilting‑pad journal bearings under steady‑state operation (constant load and shaft speed). It is intended for designers and engineers who need a simplified, reliable method when more complex CFD or elastohydrodynamic solutions are not available.

Key topics and requirements

• Scope & assumptions
  • Steady‑state operation only (no unsteady/transient states).
  • Numerous simplifying assumptions; users must evaluate results against physical implications and practical measurements (e.g., bearing temperature).
  • Recommended for journal circumferential speeds up to ~90 m/s and specific p·U values up to ≈200 MPa·m/s.
• Calculation modules covered
  • Load‑carrying capacity (bearing load prediction)
  • Frictional power and coefficient of friction
  • Lubricant flow rates (entrance/exit and side flows)
  • Heat balance and maximum lubricant film temperature
  • Maximum lubricant film pressure and admissible limits
  • Operating state classification (transition to mixed friction)
• Outputs and design parameters
  • Minimum film thickness, maximum film pressure, lubricant temperature rise, frictional power
  • Reference parameters such as Sommerfeld number, Reynolds number and flow parameters
• Interlinked standards
  • Stiffness and damping coefficients needed for vibration and stability analyses are given in ISO/TS 31657‑2 and ISO/TS 31657‑3.

Applications

ISO/TS 31657-1:2020 is directly applicable to the design, optimisation and preliminary analysis of plain journal bearings used in:

• Turbines, compressors and generators
• Electric motors, pumps and gearboxes
• Rotating machinery where hydrodynamic lubrication and steady‑state operation dominate

The method is useful for bearing sizing, quick performance estimates, thermal checks and early‑stage optimisation when detailed numerical models are impractical.

Who should use this standard

• Bearing designers and rotating equipment engineers
• OEMs and maintenance engineers evaluating bearing performance
• Tribologists and consultants conducting preliminary bearing assessments
• Engineering teams needing a standardized calculation method for multi‑lobed and tilting‑pad journal bearings

Related standards

• ISO/TS 31657‑2 and ISO/TS 31657‑3 - stiffness and damping coefficients for vibration and stability investigations
• References to ISO 7902 series for low‑speed circular cylindrical bearings

Keywords: ISO/TS 31657-1:2020, plain bearings, hydrodynamic journal bearings, tilting‑pad, multi‑lobed, bearing calculation method, load carrying capacity, frictional power, lubricant flow rate, heat balance, bearing design, rotating machinery.