ISO TS 31657-1-2020 PDF

Full title and description

ST 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. This technical specification provides a simplified, easy-to-use calculation procedure (with stated assumptions and preconditions) to estimate the steady-state performance of multi-lobed and tilting-pad hydrodynamic journal bearings for design and optimisation purposes.

Abstract

This technical specification defines general principles, assumptions and preconditions for calculating multi-lobed and tilting-pad journal bearings using a simplified numerical procedure. It is intended to give approximate performance predictions for steady-state operation (constant load and angular velocity) where more complex numerical methods are not available. The document emphasises awareness of the simplifying assumptions and recommends comparison with practical experience (for example temperature measurements) to evaluate results. The specification excludes unsteady operating states; related properties such as stiffness and damping coefficients are covered in companion parts.

General information

• Status: Withdrawn (was published as a Technical Specification in 2020; later revised by an International Standard).
• Publication date: June 2020 (ISO/TS edition).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 21.100.10 (Plain bearings).
• Edition / version: Edition 1 (Technical Specification, 2020).
• Number of pages: 37 (published ISO technical specification length).

Scope

Specifies a simplified calculation method for multi-lobed and tilting-pad hydrodynamic journal bearings under steady-state (stationary) operating conditions. The procedure provides characteristic values and operational guidance for design and optimisation of plain journal bearings used in machinery such as turbines, compressors, generators, electric motors, gears and pumps. The scope excludes unsteady (transient) operating states; stiffness and damping data for vibration/stability analyses are provided in companion parts of the series.

Key topics and requirements

• Presentation of an easy-to-use calculation procedure for multi-lobed and tilting-pad journal bearings, based on simplifying assumptions intended to give conservative/approximate results.
• Definition of the required input parameters, boundary conditions and assumptions for steady-state analysis.
• Guidance on interpretation of results and the need to compare calculated values with practical measurements and engineering judgement.
• Pointers to companion documents for tabulated characteristic functions, stiffness/damping coefficients and permissible operational parameter limits (Parts 2, 3 and 4 of the series).
• Explicit limitation to steady-state operation; unsteady phenomena, transient loads and time-varying operating conditions are outside the method’s validity.

Typical use and users

Engineers and designers of rotating machines (turbines, compressors, generators, motors, pumps, gearboxes) who need a practical method to estimate bearing performance when detailed CFD or full numerical solutions are unavailable. Tribologists, bearing manufacturers, maintenance engineers, and researchers performing preliminary design, sizing, operational-limit checks or comparative evaluations also commonly use this specification as a design reference.

Related standards

Companion and related documents in the same series include: ISO/TS 31657-2 (functions for multi-lobed bearings), ISO/TS 31657-3 (functions for tilting-pad bearings), and ISO/TS 31657-4 (permissible operational parameters and guide values). The technical specification ISO/TS 31657-1:2020 has been revised and replaced by ISO 31657-1:2025 (International Standard).

Keywords

plain bearings; hydrodynamic; journal bearings; multi-lobed bearings; tilting-pad bearings; steady-state; bearing calculation; tribology; bearing design.

FAQ

Q: What is this standard?

A: ST ISO TS 31657-1-2020 is a Technical Specification that provides a simplified calculation method for hydrodynamic plain journal bearings (multi-lobed and tilting-pad types) under steady-state conditions.

Q: What does it cover?

A: It covers the general principles, assumptions, input parameters and an easy-to-use calculation procedure to predict approximate performance (loads, film thicknesses, pressures, temperatures guidance) of multi-lobed and tilting-pad journal bearings in steady operation. It does not cover transient/unsteady behaviour; related numerical data and functions are supplied in Parts 2 and 3 and operational limits in Part 4.

Q: Who typically uses it?

A: Bearing and rotating‑equipment designers, tribologists, OEMs, maintenance engineers and researchers who require a practical calculation method for preliminary design, optimisation and operational checks of plain journal bearings.

Q: Is it current or superseded?

A: ISO/TS 31657-1:2020 has been withdrawn as a technical specification and superseded by the International Standard ISO 31657-1:2025; therefore the 2020 TS should be considered superseded by the 2025 published standard. Users should consult the 2025 edition for the current normative text.

Q: Is it part of a series?

A: Yes. It is part of a multi-part series addressing hydrodynamic plain journal bearings under steady-state conditions: Part 1 (calculation method), Part 2 (functions for multi-lobed bearings), Part 3 (functions for tilting-pad bearings) and Part 4 (permissible operational parameters / guide values).

Q: What are the key keywords?

A: Plain bearings, hydrodynamic, journal bearings, multi-lobed, tilting-pad, steady-state, calculation method, bearing design.