ISO 4378-1:2024
(Main)Plain bearings — Terms, definitions, classification and symbols — Part 1: Design, bearing materials and their properties
Plain bearings — Terms, definitions, classification and symbols — Part 1: Design, bearing materials and their properties
This document specifies the most commonly used terms relating to design, bearing materials and their properties of plain bearings with their definitions and classification. For some terms and word combinations, their short forms are given, which can be used where they are unambiguous.
Paliers lisses — Termes, définitions, classification et symboles — Partie 1: Conception, matériaux pour paliers et leurs propriétés
L'ISO 4378-1:2017 donne les termes les plus couramment utilisés concernant la conception, les matériaux pour paliers et les propriétés des paliers lisses, ainsi que leur définition et leur classification. Les formes abrégées données pour certains termes peuvent être employées dans les cas où elles ne créent aucune ambiguïté possible quant à leur interprétation. Les termes suffisamment explicites par eux-mêmes ne sont pas définis.
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 4378-1
Fifth edition
Plain bearings — Terms, definitions,
2024-11
classification and symbols —
Part 1:
Design, bearing materials and their
properties
Paliers lisses — Termes, définitions, classification et symboles —
Partie 1: Conception, matériaux pour paliers et leurs propriétés
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms .1
3.2 Terms related to types of plain bearings and classification .1
3.2.1 Classification according to the type of load .1
3.2.2 Classification according to the direction of the acting load .2
3.2.3 Classification according to the type of lubrication .3
3.2.4 Classification according to the design.9
3.3 Terms related to structural elements of plain bearing assembly .16
3.4 Terms related to structural elements of plain bearing .24
3.5 Terms related to dimensional characteristics of plain bearing .31
3.6 Terms related to materials and their properties .41
Bibliography .44
Index .45
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee TC 123, Plain bearings, Subcommittee SC 6, Terms and
common items.
This fifth edition cancels and replaces the fourth edition (ISO 4378-1:2017), which has been technically
revised.
The main changes are as follows:
— addition of several new terms, key references and an alphabetical index.
A list of all parts in the ISO 4378 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
As there is a large number of multiple designations in the domain of plain bearings, there is a considerable
risk of error in the interpretation of standards and technical literature.
This document is an attempt to establish a uniform basic system of designations of design, bearing materials
and their properties.
v
International Standard ISO 4378-1:2024(en)
Plain bearings — Terms, definitions, classification and
symbols —
Part 1:
Design, bearing materials and their properties
1 Scope
This document specifies the most commonly used terms relating to design, bearing materials and their
properties of plain bearings with their definitions and classification.
For some terms and word combinations, their short forms are given, which can be used where they are
unambiguous.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms
3.1.1
bearing
mechanical component by means of which a part in relative motion is supported and/or guided with respect
to other parts of a mechanism
3.1.2
plain bearing
sliding bearing
bearing (3.1.1) in which the type of relative motion is sliding
3.1.3
plain bearing unit
mechanical component of a tribological system including a plain bearing (3.1.2), its supporting part (e.g. a
housing), a shaft and a lubricating system
3.2 Terms related to types of plain bearings and classification
3.2.1 Classification according to the type of load
3.2.1.1
statically loaded plain bearing
plain bearing (3.1.2) operating under a load constant in magnitude and direction
3.2.1.2
dynamically loaded plain bearing
plain bearing (3.1.2) operating under a load changing in magnitude and/or direction
3.2.2 Classification according to the direction of the acting load
3.2.2.1
plain journal bearing
journal bearing
plain bearing (3.1.2) in which the load acts radially to the axis of the rotating shaft
Note 1 to entry: See Figures 1 and 3.
Key
1 plain journal bearing
2 journal (3.3.8)
d journal diameter (3.5.32), shaft diameter (3.5.33)
Figure 1 — Plain journal bearing
3.2.2.2
plain thrust bearing
thrust bearing
plain bearing (3.1.2) in which the load acts along the axis of the rotating shaft
Note 1 to entry: See Figure 2.
Key
1 support ring
2 thrust pad (3.3.7.2)
3 thrust collar (3.3.9)
d collar diameter (3.5.34)
Figure 2 — Plain thrust bearing
3.2.2.3
journal thrust bearing
flanged bearing
plain bearing (3.1.2) capable of supporting a load in both the axial and radial directions
3.2.3 Classification according to the type of lubrication
3.2.3.1
hydrodynamic bearing
plain bearing (3.1.2) operating under conditions of hydrodynamic lubrication
Note 1 to entry: See Figure 3.
Key
1 plain journal bearing (3.2.2.1)
2 journal (3.3.8)
F load
a
Fluid film pressure distribution.
Figure 3 — Hydrodynamic bearing
3.2.3.2
hydrostatic bearing
externally pressurized bearing
plain bearing (3.1.2) operating under conditions of hydrostatic lubrication
Note 1 to entry: See Figure 4.
Key
1 journal (3.3.8)
2 oil hole, lubrication hole (3.4.1)
3 oil pocket, lubrication indentation (3.4.3)
Figure 4 — Hydrostatic bearing
3.2.3.3
hydrodynamic gas bearing
hydrodynamic air bearing
aerodynamic bearing
plain bearing (3.1.2) operating under conditions of hydrodynamic gas/air lubrication
3.2.3.4
hydrostatic gas bearing
hydrostatic air bearing
aerostatic bearing
plain bearing (3.1.2) operating under conditions of hydrostatic gas/air lubrication
3.2.3.5
squeeze film bearing
plain bearing (3.1.2) in which complete separation of sliding surfaces is caused by the pressure developed in
the lubricant film as a result of their approach in the direction normal to the surface
Note 1 to entry: See Figure 5.
Key
1 journal (3.3.8)
F load
a
Squeezed fluid flow.
Figure 5 — Squeeze film bearing
3.2.3.6
hybrid bearing
plain bearing (3.1.2) operating under conditions of both hydrostatic and hydrodynamic lubrication
3.2.3.7
solid-film lubricated bearing
plain bearing (3.1.2) operating with a solid lubricant
Note 1 to entry: See Figure 6.
Key
1 plain bearing (3.1.2)
2 journal (3.3.8)
3 solid lubricant
Figure 6 — Solid film lubricated bearing
3.2.3.8
unlubricated bearing
plain bearing (3.1.2) operating without a lubricant
3.2.3.9
self-lubricating bearing
plain bearing (3.1.2) lubricated by the bearing material (3.6.1), by the material components or by solid
lubricant overlays
3.2.3.10
porous self-lubricating bearing
sintered bearing
oil-impregnated sintered bearing
plain bearing (3.1.2), the sliding part of which consists of material having communicating pores filled with
lubricant
Note 1 to entry: See Figure 7.
Key
1 porous bearing
2 journal (3.3.8)
a
Fluid flow.
Figure 7 — Porous self-lubricating bearing
3.2.3.11
self-contained plain bearing assembly
bearing assembly with a lubricant reservoir and means of circulating the lubricant to the bearing surface
Note 1 to entry: See plain bearing assembly (3.2.4.9).
3.2.3.12
foil bearing
hydrodynamic bearing (3.2.3.1) consisting of a thin solid material (3.6.2) with low bending stiffness, which
supports a load while allowing deflection of the thin solid material
Note 1 to entry: See Figure 8.
Key
1 journal (3.3.8)
2 top foil
3 bump foil
4 housing (3.3.11)
Figure 8 — Foil bearing
3.2.3.13
helical groove bearing
spiral groove bearing
hydrodynamic bearing (3.2.3.1) system with many shallow helical grooves on the surface of the bearing or
the shaft
Note 1 to entry: See Figure 9.
Note 2 to entry: The term “spiral groove bearing” is commonly used, although the design in Subfigures a) and b) make
use of helical grooves. In case of Subfigure c) the grooves are spiral shaped.
a) Spiral groove on the shaft surface: A
b) Spiral groove on the shaft surface: B c) Spiral groove on the thrust bearing surface
Key
1 grooves
2 journal (3.3.8)
3 plain journal bearing (3.2.2.1)
4 thrust collar (3.3.9)
5 plain thrust bearing (3.2.2.2)
Figure 9 — Spiral groove bearing
3.2.4 Classification according to the design
3.2.4.1
circular cylindrical bearing
plain journal bearing (3.2.2.1), every cross-section of the inside surface of which is a circle of the same
diameter
Note 1 to entry: See Figure 10.
Key
1 journal (3.3.8)
2 plain journal bearing (3.2.2.1)
C radial clearance of a circular cylindrical bearing (3.5.5)
Figu
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