ISO TS 31657-2-2020 PDF

Full title and description

Plain bearings — Hydrodynamic plain journal bearings under steady-state conditions — Part 2: Functions for calculation of multi-lobed journal bearings. This technical specification provides tabulated and plotted functions used for the operationally safe design and calculation of selected two-, three- and four-lobe hydrodynamic journal bearings under stationary (steady‑state) conditions.

Abstract

This document specifies characteristic values and calculation functions for selected two‑, three‑ and four‑lobe hydrodynamic journal bearings (multi‑lobed bearings) under steady‑state operation. The functions are intended to be used with the calculation principles and symbols given in Part 1 and apply only to stationary operating states; calculation examples and symbol definitions are referenced in Part 1.

General information

• Status: Withdrawn (superseded by ISO 31657-2:2025).
• Publication date: June 2020 (edition 1).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 21.100.10 (Plain bearings).
• Edition / version: Edition 1 — ISO/TS 31657-2:2020 (Technical Specification).
• Number of pages: 67 pages.

Scope

Specifies characteristic values and functions required for the safe design and operational evaluation of selected multi‑lobed (two-, three- and four‑lobe) hydrodynamic plain journal bearings under steady‑state conditions. The values and functions are based on the assumptions and boundary conditions defined in Part 1 and are intended for use in stationary operating states only. The document does not cover unsteady/transient operation or non‑standard geometries outside the tabulated selections.

Key topics and requirements

• Tabulated and plotted characteristic functions for selected multi‑lobed journal bearing geometries (two‑, three‑ and four‑lobe configurations).
• Data intended to be used together with the calculation method and symbols in Part 1.
• Assumptions and boundary conditions for steady‑state hydrodynamic calculations (laminar flow assumptions, defined lubrication pocket widths, etc.).
• Guidance for selecting characteristic values for design checks (load capacity, film thickness, frictional power and temperature considerations within the steady‑state framework).

Typical use and users

Used by mechanical design engineers, rotating‑equipment designers, bearing specialists, OEMs (turbines, compressors, generators, pumps), maintenance engineers and standards committees for bearing design, selection and verification when simplified, standardized characteristic data are required. It is useful where full CFD or elastohydrodynamic analyses are not feasible and a practical, standardized calculation route is preferred.

Related standards

Part of the ISO 31657 series on hydrodynamic plain journal bearings. Closely related documents include: ISO/TS 31657-1:2020 (Part 1 — calculation methods; later revised as ISO 31657-1:2025) and subsequent Parts addressing tilting‑pad bearings and permissible operational parameters; the whole series was revised and published as ISO 31657‑x in 2025.

Keywords

plain bearings, hydrodynamic journal bearings, multi‑lobed bearings, characteristic values, calculation functions, steady‑state, ISO/TS 31657, bearing design, load capacity, film thickness.

FAQ

Q: What is this standard?

A: ISO/TS 31657-2:2020 is a technical specification titled "Plain bearings — Hydrodynamic plain journal bearings under steady‑state conditions — Part 2: Functions for calculation of multi‑lobed journal bearings" that provides tabulated and graphical characteristic functions for selected multi‑lobed journal bearings.

Q: What does it cover?

A: It covers characteristic values and functions (for two‑, three‑ and four‑lobe journal bearings) to be used with Part 1 calculation methods for steady‑state hydrodynamic design checks (e.g., load capacity, minimum film thickness, frictional power and temperature estimates). It does not address transient operation or geometries outside the tabulated selections.

Q: Who typically uses it?

A: Bearing designers, rotating‑equipment OEMs, mechanical engineers, maintenance and reliability engineers, and standards committees use it for bearing sizing, design verification and conservative checks where standardized characteristic data are required.

Q: Is it current or superseded?

A: ISO/TS 31657-2:2020 has been withdrawn and superseded by ISO 31657-2:2025 (the 2025 edition republishes and replaces the 2020 technical specification as an International Standard). Users should reference the 2025 edition for the current, published normative content.

Q: Is it part of a series?

A: Yes — it is Part 2 of the ISO 31657 series on hydrodynamic plain journal bearings; Part 1 covers calculation methods (ISO/TS 31657-1:2020, now revised as ISO 31657-1:2025), and other parts in the series address tilting‑pad bearings and permissible operational parameters.

Q: What are the key keywords?

A: Plain bearings; journal bearings; hydrodynamic lubrication; multi‑lobed bearings; characteristic values; calculation functions; steady‑state operation; bearing design.