SIST ISO 3548-1:2023

Plain bearings - Thin-walled half bearings with or without flange - Part 1: Tolerances, design features and methods of test

This document specifies tolerances, design features and test methods for thin-walled half bearings with integral flange up to an outside diameter of Do = 250 mm and without flange up to an outside diameter of Do = 500 mm. Due to the variety of design, it is, however, not possible to standardize the dimensions of the half bearings.
Half bearings according to this document are predominantly used in reciprocating machinery and consist of a steel backing and one or more bearing metal layers on the inside.
In reciprocating machinery, flanged half bearings can be used in connection with half bearings without flange.
Alternatively, to serve as a flanged half bearing, it is possible to use a half bearing without flange together with two separate half thrust washers according to ISO 6526, or a half bearing with assembled flanges.
NOTE All dimensions and tolerances are given in millimetres.

Paliers lisses - Demi-coussinets minces à ou sans collerette - Partie 1: Tolérances, caractéristiques de conception et méthodes d'essai

Drsni ležaji - Tankostene ležajne blazinice s prirobnico ali brez nje - 1. del: Tolerance, konstrukcija in metode preskušanja

Ta dokument določa tolerance, konstrukcijo in metode preskušanja za tankostene ležajne blazinice z integralno prirobnico z zunanjim premerom Do = 250 mm in brez prirobnice z zunanjim premerom do Do = 500 mm. Zaradi različne konstrukcije ni mogoče standardizirati mer ležajnih blazinic.
Ležajne blazinice v skladu s tem dokumentom se uporabljajo predvsem v batnih strojih in so sestavljene iz jeklene podlage in ene ali več ležajnih kovinskih plasti na notranji strani.
V batnih strojih je mogoče ležajne blazinice s prirobnicami uporabiti skupaj z ležajnimi blazinicami brez prirobnice.
Alternativno se lahko kot ležajne blazinice s prirobnicami uporabijo ležajne blazinice brez prirobnice skupaj z dvema ločenima opornima podlogama iz standarda ISO 6526 ali ležajne blazinice s sestavljenimi prirobnicami.
OPOMBA: Vse mere in tolerance so navedene v milimetrih.

General Information

• Status: Published
• Publication Date: 13-Mar-2023
• ICS: 21.100.10 - Plain bearings
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 08-Mar-2023
• Due Date: 13-May-2023
• Completion Date: 14-Mar-2023
• Ref Project: ISO 3548-1:2022 - Plain bearings - Thin-walled half bearings with or without flange - Part 1: Tolerances, design features and methods of test

Relations

• Revises: SIST ISO 3548-1:2015 - Plain bearings - Thin-walled half bearings with or without flange - Part 1: Tolerances, design features and methods of test
• Effective Date: 23-Apr-2020

Overview

ISO 3548-1:2022 - Plain bearings: Thin-walled half bearings with or without flange - Part 1 specifies tolerances, design features and test methods for thin-walled half bearings used predominantly in reciprocating machinery. The standard covers half bearings with integral flanges up to an outside diameter Do = 250 mm and without flanges up to Do = 500 mm. All dimensions and tolerances are given in millimetres. This second edition (2022) updates symbols, figures and normative references to reflect current measurement and manufacturing practice.

Key topics and technical requirements

• Scope & limits: Flanged half bearings ≤ 250 mm outside diameter; non‑flanged ≤ 500 mm. Dimensions are flexible and peripheral length is measured rather than direct outside diameter.
• Tolerances: Specified for crush height, wall thickness and widths - tolerances differ for “as‑machined” versus “as‑plated” bearing bores. Housing diameter manufacturing tolerance recommended as H6 (ISO 286‑2).
• Measurement methods: Peripheral length measured with special checking fixtures; two checking methods (A and B) and procedures for calculating the effective test force F are defined.
• Design features: Guidance on locating nicks and recesses, reliefs and chamfers, transition between radial part and flange, assembled flange toes, oil grooves and oil holes, and permissible surface roughness of sliding surfaces.
• Eccentric bores: Accepts eccentric (crowned) bore designs; eccentricity controlled via a specified wall‑thickness reduction u measured at defined angles/points.
• Assembled flange function: Test data and classification for assembled flange bearings including axial width checks and checklist items to ensure correct function under load.
• Units and symbols: Complete symbol table and diagrams for dimensions such as a (crush height), s (wall thickness), B (width), P (free spread), and Ra (surface roughness).

Applications and users

• Who uses it: Mechanical designers, plain bearing manufacturers, OEMs of reciprocating engines and compressors, quality/control engineers, test laboratories and procurement/specification writers.
• Practical uses:
  • Specify and verify bearing components for reciprocating machinery.
  • Ensure correct interference fit and housing tolerances (H6) for reliable service.
  • Define inspection and test procedures for peripheral length, crush height and assembled flange performance.
  • Guide layout of oil grooves, locating nicks and chamfers to optimize function and assembly.

Related standards

• ISO 3548-3 - Measurement of peripheral length for thin-walled half bearings
• ISO 6526 - Pressed bimetallic half thrust washers - features and tolerances
• ISO 21920-3 - Surface texture (profile) - specification operators

Practical takeaway: ISO 3548-1:2022 is the authoritative reference for designers and manufacturers of thin‑walled half bearings, providing standardized tolerances, mandatory testing approaches and design guidance to ensure interchangeability and reliable operation in reciprocating machinery. Keywords: ISO 3548-1:2022, thin-walled half bearings, plain bearings, tolerances, test methods, flanged half bearings, crush height, peripheral length.

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2023
Drsni ležaji - Tankostene ležajne blazinice s prirobnico ali brez nje - 1. del:
Tolerance, konstrukcija in metode preskušanja
Plain bearings - Thin-walled half bearings with or without flange - Part 1: Tolerances,
design features and methods of test
Paliers lisses - Demi-coussinets minces à ou sans collerette - Partie 1: Tolérances,
caractéristiques de conception et méthodes d'essai
Ta slovenski standard je istoveten z: ISO 3548-1:2022
ICS:
21.100.10 Drsni ležaji Plain bearings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 3548-1
Second edition
2022-08
Plain bearings — Thin-walled half
bearings with or without flange —
Part 1:
Tolerances, design features and
methods of test
Paliers lisses — Demi-coussinets minces à ou sans collerette —
Partie 1: Tolérances, caractéristiques de conception et méthodes
d'essai
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Dimensions and tolerances .4
5.1 Housing diameter, half bearing outside diameter and crush height . 4
5.2 Half bearing wall thickness and bearing bore . 4
5.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness . 6
5.4 Free spread . 7
6 Design features .10
6.1 General . 10
6.2 Locating nick and recess . 10
6.3 Reliefs and chamfers . 11
6.4 Transition between radial part and flange .12
6.5 Assembled flange scalloped toes. 14
6.6 Oil grooves and holes . 14
7 Test data for determining the peripheral length .17
7.1 Calculation of test force F. 17
7.2 Checking method A . 18
7.3 Checking method B . 19
8 Test data for determining axial width, B , of flange bearings .19
8.1 General . 19
8.2 Go between two parallel plates . 19
8.3 Axial width B checked under force . 20
9 Function and characteristics of assembled flange bearings .20
9.1 General . 20
9.2 Characteristics. 21
9.3 Classification . 22
9.4 Checklist of items for ensuring the function of assembled flange bearings.22
Bibliography .23
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions 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 ISO/TC 123, Plain Bearings, Subcommittee SC 3,
Dimensions, tolerances and constructions details.
This second edition cancels and replaces the first edition (ISO 3548:2014), which has been technically
revised.
The main changes are as follows:
— normative references have been revised in Clause 2;
— symbols and terms with units have been added to Table 1;
— symbols in Figure 2 have been modified;
— symbols and measures in Figure 7 have been modified;
— Figures 3, 10 and 11 have been modified;
— symbols in 7.2 and 7.3 have been modified.
A list of all parts in the ISO 3548 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
INTERNATIONAL STANDARD ISO 3548-1:2022(E)
Plain bearings — Thin-walled half bearings with or
without flange —
Part 1:
Tolerances, design features and methods of test
1 Scope
This document specifies tolerances, design features and test methods for thin-walled half bearings with
integral flange up to an outside diameter of D = 250 mm and without flange up to an outside diameter
o
of D = 500 mm. Due to the variety of design, it is, however, not possible to standardize the dimensions
o
of the half bearings.
Half bearings according to this document are predominantly used in reciprocating machinery and
consist of a steel backing and one or more bearing metal layers on the inside.
In reciprocating machinery, flanged half bearings can be used in connection with half bearings without
flange.
Alternatively, to serve as a flanged half bearing, it is possible to use a half bearing without flange
together with two separate half thrust washers according to ISO 6526, or a half bearing with assembled
flanges.
NOTE All dimensions and tolerances are given in millimetres.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3548-3, Plain bearings — Thin-walled half bearings with or without flange — Part 3: Measurement of
peripheral length
ISO 6526, Plain bearings — Pressed bimetallic half thrust washers — Features and tolerances
ISO 21920-3, Geometrical product specifications (GPS) — Surface texture: Profile — Part 3: Specification
operators
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology 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/
4 Symbols
Symbols and units are shown in Figures 1 and 2 and Table 1.
Key
1 joint face
2 sliding surface
3 bearing metal
4 bearing back
5 steel bearing backing
Figure 1 — Half bearing without flange with positive free spread
Figure 2 — Flange half bearing, integral or assembled, excluding free spread
Table 1 — Symbols and units
Symbol Description Unit
a Crush height mm
a Crush height in checking method A mm
A
a Crush height in checking method B mm
B
a Crush height on first joint face side in checking method B mm
B1
a Crush height on second joint face side in checking method B mm
B2
a Measuring point perpendicular to plane of joint face mm
a Circumferential length of locating nick mm
a Locating nick protrusion mm
a Locating recess depth mm
a Bearing bore relief length mm
a Sliding relief length mm
a Sliding relief length under 10° inclination mm
a Bending transition length mm
a Undercut length mm
a Groove centre distance mm
A Reduced area of cross section (calculated value) of half bearing mm
cal
A Face area of flange mm
f
b Distance to locating nick mm
b Locating nick width mm
b Distance recess centre to locating nick mm
b Distance locating nick groove to lubrication hole mm
b Locating recess width mm
b Clearance mm
b Oil groove width mm
G
b Housing width mm
H
B Half bearing width (without flange) mm
B Flange half bearing width mm
B Distance between flanges mm
c Inside chamfer mm
i
c Outside chamfer mm
o
d Diameter of the checking block bore mm
cb
d Housing diameter mm
H
D Outside diameter of flange mm
D Nominal inside diameter of the half bearing (bearing bore) mm
i
D Nominal outside diameter of the half bearing mm
o
D Outside diameter of the half bearing in the free state (with free spread) mm
o,E
e Amount of eccentricity mm
B
F Test force N
F Axial test force for assembled flange bearings N
ax
i Bearing bore relief height mm
i Flange bearing, sliding relief length mm
i Flange bearing, sliding relief length under 10° inclination mm
L Bottom limit of u —
Bu
L Upper limit of u —
Uu
Table 1 (continued)
Symbol Description Unit
P Amount of free spread mm
Ra Arithmetic average surface roughness µm
s Wall thickness (general) mm
s Steel backing thickness mm
s Bearing metal thickness mm
s Half bearing wall thickness mm
s Actual value of s —
3, act 3
s Wall thickness at the base of the groove mm
s Contact width assembled flange with half bearing mm
s Assembled flange joint thickness mm
s Flange thickness mm
s Wall thickness at different angle mm
α
s Bottom value of s —
α, BL α
s Upper value of s —
α, UL α
u Amount of wall thickness reduction for eccentric bearing mm
x Tolerance, position limit of oil groove and oil hole mm
x Centre of the bearing outside surface —
x Centre of the bearing bore —
α Angle °
α Angle at eccentricity measuring point °
β Chamfer angle of oil groove °
5 Dimensions and tolerances
5.1 Housing diameter, half bearing outside diameter and crush height
The housing diameter should be manufactured to limit deviations H6 as defined in ISO 286-2. The half
bearing outside diameter shall be selected with such an oversize that an adequate interference fit is
ensured in the housing diameter.
In the case of housings made from materials having a high coefficient of expansion or where other
factors such as housing dimensional stability are involved, the housing size may depart from tolerance
class H6 but shall always be produced in accordance with standard tolerance grade 6 values.
The half bearing in a free state is flexible so that its outside diameter cannot be measured directly.
Instead of this, its peripheral length is determined by means of special checking fixtures. The peripheral
length results from the periphery of the checking block bore and the crush height taking into account
the reduction under a given checking load per joint face (see Clause 6). The calculation of the effective
interference fit of the half bearings in the housing is provided in Reference [7].
The tolerances given in Table 2 for the crush height apply to half bearings with machined joint faces.
Different materials and housing design require different interference fits, therefore only tolerances are
given in Table 2.
5.2 Half bearing wall thickness and bearing bore
Nominal dimensions to be preferred for the wall thickness of the bearing are given in Table 2 (the
particulars of the wall thickness for each application cannot be specified in general). Therefore, only
tolerances can be given for the wall thickness. These tolerances and the surface roughnesses of the
bearing back and the sliding surface of half bearings with or without electroplated antifriction layers
are given in Table 2.
The tolerance for the half bearing wall thickness depends on the fact whether the bearing bore is
subject to a final machining operation (i.e. “as machined”) or whether the bearing bore is electroplated
without further machining (i.e. “as-plated”).
Slight surface deformations are acceptable on the outside diameter of the bearing provided that they
are not numerous. However, the measurement of the wall thickness shall not be carried out in these
areas.
The bearing bore in the fitted state results from the housing bore which is elastically enlarged by the
[7]
press fit, reduced by twice the value of the half bearing wall thickness .
NOTE In certain applications, it can be necessary to use plain or flange half bearings with eccentric bores,
i.e. the wall thickness of the half bearing decreases uniformly from the crown to the joint faces (see Figures 3 and
4).
The eccentricity e is characterized in a radial plane by the distance between the centre x of the
B 1
bearing outside surface and the centre x of the bearing bore. e is not dimensioned specifically. The
2 B
eccentricity is controlled by the specified reduction u which is measured at a vertical distance a from
the plane of the joint face. For guidance of draughtsmen, a is generally specified so that the angle α is
1 2
approximately 25° from the joint face. The measuring point is subject to agreement between the user
and manufacturer.
Key
x centre of the bearing outside surface
x centre of the bearing bore
Figure 3 — Eccentric bearing bore of half bearing
Key
1 joint face
2 crown
Figure 4 — Example of the wall thickness at different angles
The tolerance limit for the behaviour of wall thickness can be calculated using Formulae 1 and 2:
1−sinα
ss=−L ⋅ (1)
α,,BL 3 actBu
1−sinα
1−sinα
ss=−L ⋅ (2)
α,,UL 3 actUu
1−sinα
where
L is the bottom limit of u;
Bu
L is the upper limit of u;
Uu
s is the actual value of s ;
3, act 3
s is the bottom value of s ;
α, BL α
s is the upper value of s .
α, UL α
5.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness
The nominal dimension for the half bearing width and the distance between flanges depends upon the
type of application, the common ratio being B (B )/D ≤ 0,5. The tolerances for the half bearing width
1 2 i
are given in Table 2. The flange outside diameter should be smaller than the diameter of the shoulder of
the shaft and smaller than the diameter of the housing block.
In most cases, the flange thickness is fixed in conformity with the half bearing wall thickness and, in
general, a tolerance is fixed only for the flange thickness of the pressure loaded side in order to ensure
that these flanges of the upper and lower half bearing have approximately the same thickness. In this
case, the position of these flanges with respect to the locating lips is fixed.
If the upper and lower half bearings are of the same design, then generally the two flanges of one half
bearing shall have the same thickness within the tolerance range fixed in Table 2. In that case, the flange
thicknesses result from the bearing width and the distance between flanges. Nevertheless, another
tolerance can be accepted after agreement between the user and the manufacturer (see Clause 7).
5.4 Free spread
Free spread is influenced by factors such as the lining material, its thickness and its physical properties,
by the bearing backing material and its properties, and by the operating temperature of the assembly.
Since these features are not specified in thi
...

INTERNATIONAL ISO
STANDARD 3548-1
Second edition
2022-08
Plain bearings — Thin-walled half
bearings with or without flange —
Part 1:
Tolerances, design features and
methods of test
Paliers lisses — Demi-coussinets minces à ou sans collerette —
Partie 1: Tolérances, caractéristiques de conception et méthodes
d'essai
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Dimensions and tolerances .4
5.1 Housing diameter, half bearing outside diameter and crush height . 4
5.2 Half bearing wall thickness and bearing bore . 4
5.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness . 6
5.4 Free spread . 7
6 Design features .10
6.1 General . 10
6.2 Locating nick and recess . 10
6.3 Reliefs and chamfers . 11
6.4 Transition between radial part and flange .12
6.5 Assembled flange scalloped toes. 14
6.6 Oil grooves and holes . 14
7 Test data for determining the peripheral length .17
7.1 Calculation of test force F. 17
7.2 Checking method A . 18
7.3 Checking method B . 19
8 Test data for determining axial width, B , of flange bearings .19
8.1 General . 19
8.2 Go between two parallel plates . 19
8.3 Axial width B checked under force . 20
9 Function and characteristics of assembled flange bearings .20
9.1 General . 20
9.2 Characteristics. 21
9.3 Classification . 22
9.4 Checklist of items for ensuring the function of assembled flange bearings.22
Bibliography .23
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions 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 ISO/TC 123, Plain Bearings, Subcommittee SC 3,
Dimensions, tolerances and constructions details.
This second edition cancels and replaces the first edition (ISO 3548:2014), which has been technically
revised.
The main changes are as follows:
— normative references have been revised in Clause 2;
— symbols and terms with units have been added to Table 1;
— symbols in Figure 2 have been modified;
— symbols and measures in Figure 7 have been modified;
— Figures 3, 10 and 11 have been modified;
— symbols in 7.2 and 7.3 have been modified.
A list of all parts in the ISO 3548 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
INTERNATIONAL STANDARD ISO 3548-1:2022(E)
Plain bearings — Thin-walled half bearings with or
without flange —
Part 1:
Tolerances, design features and methods of test
1 Scope
This document specifies tolerances, design features and test methods for thin-walled half bearings with
integral flange up to an outside diameter of D = 250 mm and without flange up to an outside diameter
o
of D = 500 mm. Due to the variety of design, it is, however, not possible to standardize the dimensions
o
of the half bearings.
Half bearings according to this document are predominantly used in reciprocating machinery and
consist of a steel backing and one or more bearing metal layers on the inside.
In reciprocating machinery, flanged half bearings can be used in connection with half bearings without
flange.
Alternatively, to serve as a flanged half bearing, it is possible to use a half bearing without flange
together with two separate half thrust washers according to ISO 6526, or a half bearing with assembled
flanges.
NOTE All dimensions and tolerances are given in millimetres.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3548-3, Plain bearings — Thin-walled half bearings with or without flange — Part 3: Measurement of
peripheral length
ISO 6526, Plain bearings — Pressed bimetallic half thrust washers — Features and tolerances
ISO 21920-3, Geometrical product specifications (GPS) — Surface texture: Profile — Part 3: Specification
operators
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology 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/
4 Symbols
Symbols and units are shown in Figures 1 and 2 and Table 1.
Key
1 joint face
2 sliding surface
3 bearing metal
4 bearing back
5 steel bearing backing
Figure 1 — Half bearing without flange with positive free spread
Figure 2 — Flange half bearing, integral or assembled, excluding free spread
Table 1 — Symbols and units
Symbol Description Unit
a Crush height mm
a Crush height in checking method A mm
A
a Crush height in checking method B mm
B
a Crush height on first joint face side in checking method B mm
B1
a Crush height on second joint face side in checking method B mm
B2
a Measuring point perpendicular to plane of joint face mm
a Circumferential length of locating nick mm
a Locating nick protrusion mm
a Locating recess depth mm
a Bearing bore relief length mm
a Sliding relief length mm
a Sliding relief length under 10° inclination mm
a Bending transition length mm
a Undercut length mm
a Groove centre distance mm
A Reduced area of cross section (calculated value) of half bearing mm
cal
A Face area of flange mm
f
b Distance to locating nick mm
b Locating nick width mm
b Distance recess centre to locating nick mm
b Distance locating nick groove to lubrication hole mm
b Locating recess width mm
b Clearance mm
b Oil groove width mm
G
b Housing width mm
H
B Half bearing width (without flange) mm
B Flange half bearing width mm
B Distance between flanges mm
c Inside chamfer mm
i
c Outside chamfer mm
o
d Diameter of the checking block bore mm
cb
d Housing diameter mm
H
D Outside diameter of flange mm
D Nominal inside diameter of the half bearing (bearing bore) mm
i
D Nominal outside diameter of the half bearing mm
o
D Outside diameter of the half bearing in the free state (with free spread) mm
o,E
e Amount of eccentricity mm
B
F Test force N
F Axial test force for assembled flange bearings N
ax
i Bearing bore relief height mm
i Flange bearing, sliding relief length mm
i Flange bearing, sliding relief length under 10° inclination mm
L Bottom limit of u —
Bu
L Upper limit of u —
Uu
Table 1 (continued)
Symbol Description Unit
P Amount of free spread mm
Ra Arithmetic average surface roughness µm
s Wall thickness (general) mm
s Steel backing thickness mm
s Bearing metal thickness mm
s Half bearing wall thickness mm
s Actual value of s —
3, act 3
s Wall thickness at the base of the groove mm
s Contact width assembled flange with half bearing mm
s Assembled flange joint thickness mm
s Flange thickness mm
s Wall thickness at different angle mm
α
s Bottom value of s —
α, BL α
s Upper value of s —
α, UL α
u Amount of wall thickness reduction for eccentric bearing mm
x Tolerance, position limit of oil groove and oil hole mm
x Centre of the bearing outside surface —
x Centre of the bearing bore —
α Angle °
α Angle at eccentricity measuring point °
β Chamfer angle of oil groove °
5 Dimensions and tolerances
5.1 Housing diameter, half bearing outside diameter and crush height
The housing diameter should be manufactured to limit deviations H6 as defined in ISO 286-2. The half
bearing outside diameter shall be selected with such an oversize that an adequate interference fit is
ensured in the housing diameter.
In the case of housings made from materials having a high coefficient of expansion or where other
factors such as housing dimensional stability are involved, the housing size may depart from tolerance
class H6 but shall always be produced in accordance with standard tolerance grade 6 values.
The half bearing in a free state is flexible so that its outside diameter cannot be measured directly.
Instead of this, its peripheral length is determined by means of special checking fixtures. The peripheral
length results from the periphery of the checking block bore and the crush height taking into account
the reduction under a given checking load per joint face (see Clause 6). The calculation of the effective
interference fit of the half bearings in the housing is provided in Reference [7].
The tolerances given in Table 2 for the crush height apply to half bearings with machined joint faces.
Different materials and housing design require different interference fits, therefore only tolerances are
given in Table 2.
5.2 Half bearing wall thickness and bearing bore
Nominal dimensions to be preferred for the wall thickness of the bearing are given in Table 2 (the
particulars of the wall thickness for each application cannot be specified in general). Therefore, only
tolerances can be given for the wall thickness. These tolerances and the surface roughnesses of the
bearing back and the sliding surface of half bearings with or without electroplated antifriction layers
are given in Table 2.
The tolerance for the half bearing wall thickness depends on the fact whether the bearing bore is
subject to a final machining operation (i.e. “as machined”) or whether the bearing bore is electroplated
without further machining (i.e. “as-plated”).
Slight surface deformations are acceptable on the outside diameter of the bearing provided that they
are not numerous. However, the measurement of the wall thickness shall not be carried out in these
areas.
The bearing bore in the fitted state results from the housing bore which is elastically enlarged by the
[7]
press fit, reduced by twice the value of the half bearing wall thickness .
NOTE In certain applications, it can be necessary to use plain or flange half bearings with eccentric bores,
i.e. the wall thickness of the half bearing decreases uniformly from the crown to the joint faces (see Figures 3 and
4).
The eccentricity e is characterized in a radial plane by the distance between the centre x of the
B 1
bearing outside surface and the centre x of the bearing bore. e is not dimensioned specifically. The
2 B
eccentricity is controlled by the specified reduction u which is measured at a vertical distance a from
the plane of the joint face. For guidance of draughtsmen, a is generally specified so that the angle α is
1 2
approximately 25° from the joint face. The measuring point is subject to agreement between the user
and manufacturer.
Key
x centre of the bearing outside surface
x centre of the bearing bore
Figure 3 — Eccentric bearing bore of half bearing
Key
1 joint face
2 crown
Figure 4 — Example of the wall thickness at different angles
The tolerance limit for the behaviour of wall thickness can be calculated using Formulae 1 and 2:
1−sinα
ss=−L ⋅ (1)
α,,BL 3 actBu
1−sinα
1−sinα
ss=−L ⋅ (2)
α,,UL 3 actUu
1−sinα
where
L is the bottom limit of u;
Bu
L is the upper limit of u;
Uu
s is the actual value of s ;
3, act 3
s is the bottom value of s ;
α, BL α
s is the upper value of s .
α, UL α
5.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness
The nominal dimension for the half bearing width and the distance between flanges depends upon the
type of application, the common ratio being B (B )/D ≤ 0,5. The tolerances for the half bearing width
1 2 i
are given in Table 2. The flange outside diameter should be smaller than the diameter of the shoulder of
the shaft and smaller than the diameter of the housing block.
In most cases, the flange thickness is fixed in conformity with the half bearing wall thickness and, in
general, a tolerance is fixed only for the flange thickness of the pressure loaded side in order to ensure
that these flanges of the upper and lower half bearing have approximately the same thickness. In this
case, the position of these flanges with respect to the locating lips is fixed.
If the upper and lower half bearings are of the same design, then generally the two flanges of one half
bearing shall have the same thickness within the tolerance range fixed in Table 2. In that case, the flange
thicknesses result from the bearing width and the distance between flanges. Nevertheless, another
tolerance can be accepted after agreement between the user and the manufacturer (see Clause 7).
5.4 Free spread
Free spread is influenced by factors such as the lining material, its thickness and its physical properties,
by the bearing backing material and its properties, and by the operating temperature of the assembly.
Since these features are not specified in this document, it is not possible to specify free spread. Free
spread shall in all circumstances be positive. After operation in the combustion engine at normal
conditions, a sufficient amount of free spread remains in the bearing to enable it to be refitted. The
actual amount of free spread shall be the subject of agreement between the manufacturer and user.
Half bearings for reciprocating machinery normally have a free spread
...