ISO 3548-1:2014
(Main)Plain bearings — Thin-walled half bearings with or without flange — Part 1: Tolerances, design features and methods of test
Plain bearings — Thin-walled half bearings with or without flange — Part 1: Tolerances, design features and methods of test
ISO 3548-1:2014 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 ISO 3548-1:2014 are predominantly used in reciprocating machinery and consist of a steel backing and one or more bearing metal layers on the inside.
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 del standarda ISO 3548 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 se v skladu s tem delom standarda ISO 3548 uporabljajo predvsem v batnih strojih ter
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
prirobnic.
Kot ležajne blazinice s prirobnicami se lahko 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
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 3548-1:2015
01-marec-2015
1DGRPHãþD
SIST ISO 3548:2002
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 3548-1:2014
ICS:
21.100.10 Drsni ležaji Plain bearings
SIST ISO 3548-1:2015 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 3548-1:2015
---------------------- Page: 2 ----------------------
SIST ISO 3548-1:2015
INTERNATIONAL ISO
STANDARD 3548-1
First edition
2014-06-15
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 3548-1:2014(E)
©
ISO 2014
---------------------- Page: 3 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Symbols . 1
4 Dimensions and tolerances . 3
4.1 Housing diameter, half bearing outside diameter and crush height. 3
4.2 Half bearing wall thickness and bearing bore . 4
4.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness . 5
4.4 Free spread . 6
5 Design features. 7
5.1 Locating lip and recess . 7
5.2 Reliefs and chamfers . 9
5.3 Transition between radial part and flange .10
5.4 Assembled flange scalloped toes .12
5.5 Oil grooves and holes .12
6 Test data for determining the peripheral length .15
6.1 Calculation of test force F . 15
6.2 Checking method A .16
6.3 Checking method B . .17
7 Test data for determining axial width, B , of flange bearings .17
2
7.1 Go between two parallel plates.17
7.2 Axial width B checked under force .18
2
8 Function and characteristics of assembled flange bearings .18
8.1 Characteristics .19
8.2 Classification .20
8.3 Checklist of items for ensuring the function of assembled flange bearings .20
Annex A (normative) Example of calculation .21
Bibliography .22
© ISO 2014 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 123, Plain Bearings, Subcommittee SC 3 Dimen-
sions, tolerances and constructions details.,
This first edition of ISO 3548-1 cancels and replaces the second edition of ISO 3548:1999, which has been
technically revised.
ISO 3548 consists of the following parts, under the general title Plain bearings — Thin walled half bearings
with or without flange:
— Part 1: Tolerances, design features and methods of test
— Part 2: Measurement of wall thickness and flange thickness
— Part 3: Measurement of peripheral length
iv © ISO 2014 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 3548-1:2015
INTERNATIONAL STANDARD ISO 3548-1:2014(E)
Plain bearings — Thin-walled half bearings with or
without flange —
Part 1:
Tolerances, design features and methods of test
1 Scope
This part of ISO 3548 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
o
outside diameter of D = 500 mm. Due to the variety of design, it is, however, not possible to standardize
o
the dimensions of the half bearings.
Half bearings according to this part of ISO 3548 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, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 4288, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Rules and
procedures for the assessment of surface texture
ISO 6524, Plain bearings — Thin-walled half bearings — Checking of peripheral length
ISO 6526, Plain bearings — Pressed bimetallic half thrust washers — Features and tolerances
3 Symbols
See Figures 1 and 2 and Table 1.
© ISO 2014 – All rights reserved 1
---------------------- Page: 7 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
Key
1 joint face
2 sliding surface
3 bearing metal
4 bearing back
5 steel back
Figure 1 — Half bearing without flange
(with positive free spread)
Figure 2 — Flange half bearing
(integral or assembled, excluding free spread)
2 © ISO 2014 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
Table 1 — Symbols and units
Symbol Term Unit
a Measuring point perpendicular to plane of joint face mm
1
2
A Reduced area of cross section (calculated value) of half bearing mm
cal
b Housing width mm
H
B Half bearing width (without flange) mm
1
B Flange half bearing width mm
2
B Distance between flanges mm
3
C Outside chamfer mm
1
C Inside chamfer mm
2
d Diameter of the checking block bore mm
ch
d Housing diameter mm
H
D Outside diameter of flange mm
fl
D Nominal Inside diameter of the half bearing (bearing bore) mm
i
D Nominal Outside diameter of the half bearing mm
o
Outside diameter of the half bearing in the free state (with free
D mm
o,E
spread)
e Amount of eccentricity mm
B
F Test force N
F Axial test force for assembled flange bearings N
ax
h Crush height, h = h + h (in checking method B) mm
1 2
p Amount of free spread mm
s Flange thickness mm
fl
s Thickness of the steel backing mm
1
s Bearing metal thickness mm
2
s Half bearing wall thickness mm
3
s Wall thickness at base of groove mm
4
u Amount of wall thickness reduction for eccentric bearing mm
4 Dimensions and tolerances
4.1 Housing diameter, half bearing outside diameter and crush height
The housing diameter should be manufactured to ISO H6 limits. Thereby 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 a grade 6 tolerance.
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). For the calculation of the effective
interference fit of the half bearings in the housing, see Reference [5].
© ISO 2014 – All rights reserved 3
---------------------- Page: 9 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
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.
4.2 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
[5]
press fit, reduced by twice the value of the half bearing wall thickness.
NOTE In certain applications it might 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
1
the plane of the joint face. (For guidance of draughtsmen, a is generally specified so that the angle α
1 2
is approximately 25° from the joint face). It is subject to agreement between the user and manufacturer.
Figure 3 — Eccentric bearing bore of half bearing
4 © ISO 2014 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
Key
1 crown
2 joint face
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
_= s × (1)
s BL
α,BL u
3,act
1 − sin
α
2
1 − sinα
ss=− UL × (2)
α, 3, act
u
UL
1 − sinα
2
where
BL is the bottom limit of u;
u
UL is the upper limit of u;
u
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
For an example of calculations, see Annex A.
4.3 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).
© ISO 2014 – All rights reserved 5
---------------------- Page: 11 ----------------------
SIST ISO 3548-1:2015
ISO 3548-1:2014(E)
4.4 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 part of ISO 3548, 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 of 0,2 mm up to 3 mm. For very
large, thin-walled half bearings, the free spread may be greater but it shall not be such that the half
bearing cannot be fitted into the housing.
Table 2 — Dimensions, tolerances and limit deviations for half bearings with and without
flange
Surface rough-
bc
ness
a
Tolerance or limit deviation for
μm
Flange Dis-
Wall Flange Hous- Bear- Sliding
Housing outside tance Crush
thick- Wall thickness thick- Half bearing width ing ing sur-
f
diamet
...
INTERNATIONAL ISO
STANDARD 3548-1
First edition
2014-06-15
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 3548-1:2014(E)
©
ISO 2014
---------------------- Page: 1 ----------------------
ISO 3548-1:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 3548-1:2014(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Symbols . 1
4 Dimensions and tolerances . 3
4.1 Housing diameter, half bearing outside diameter and crush height. 3
4.2 Half bearing wall thickness and bearing bore . 4
4.3 Width of half bearing, distance between flanges, outside diameter of flange and
flange thickness . 5
4.4 Free spread . 6
5 Design features. 7
5.1 Locating lip and recess . 7
5.2 Reliefs and chamfers . 9
5.3 Transition between radial part and flange .10
5.4 Assembled flange scalloped toes .12
5.5 Oil grooves and holes .12
6 Test data for determining the peripheral length .15
6.1 Calculation of test force F . 15
6.2 Checking method A .16
6.3 Checking method B . .17
7 Test data for determining axial width, B , of flange bearings .17
2
7.1 Go between two parallel plates.17
7.2 Axial width B checked under force .18
2
8 Function and characteristics of assembled flange bearings .18
8.1 Characteristics .19
8.2 Classification .20
8.3 Checklist of items for ensuring the function of assembled flange bearings .20
Annex A (normative) Example of calculation .21
Bibliography .22
© ISO 2014 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 3548-1:2014(E)
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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 123, Plain Bearings, Subcommittee SC 3 Dimen-
sions, tolerances and constructions details.,
This first edition of ISO 3548-1 cancels and replaces the second edition of ISO 3548:1999, which has been
technically revised.
ISO 3548 consists of the following parts, under the general title Plain bearings — Thin walled half bearings
with or without flange:
— Part 1: Tolerances, design features and methods of test
— Part 2: Measurement of wall thickness and flange thickness
— Part 3: Measurement of peripheral length
iv © ISO 2014 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 3548-1:2014(E)
Plain bearings — Thin-walled half bearings with or
without flange —
Part 1:
Tolerances, design features and methods of test
1 Scope
This part of ISO 3548 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
o
outside diameter of D = 500 mm. Due to the variety of design, it is, however, not possible to standardize
o
the dimensions of the half bearings.
Half bearings according to this part of ISO 3548 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, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 4288, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Rules and
procedures for the assessment of surface texture
ISO 6524, Plain bearings — Thin-walled half bearings — Checking of peripheral length
ISO 6526, Plain bearings — Pressed bimetallic half thrust washers — Features and tolerances
3 Symbols
See Figures 1 and 2 and Table 1.
© ISO 2014 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 3548-1:2014(E)
Key
1 joint face
2 sliding surface
3 bearing metal
4 bearing back
5 steel back
Figure 1 — Half bearing without flange
(with positive free spread)
Figure 2 — Flange half bearing
(integral or assembled, excluding free spread)
2 © ISO 2014 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 3548-1:2014(E)
Table 1 — Symbols and units
Symbol Term Unit
a Measuring point perpendicular to plane of joint face mm
1
2
A Reduced area of cross section (calculated value) of half bearing mm
cal
b Housing width mm
H
B Half bearing width (without flange) mm
1
B Flange half bearing width mm
2
B Distance between flanges mm
3
C Outside chamfer mm
1
C Inside chamfer mm
2
d Diameter of the checking block bore mm
ch
d Housing diameter mm
H
D Outside diameter of flange mm
fl
D Nominal Inside diameter of the half bearing (bearing bore) mm
i
D Nominal Outside diameter of the half bearing mm
o
Outside diameter of the half bearing in the free state (with free
D mm
o,E
spread)
e Amount of eccentricity mm
B
F Test force N
F Axial test force for assembled flange bearings N
ax
h Crush height, h = h + h (in checking method B) mm
1 2
p Amount of free spread mm
s Flange thickness mm
fl
s Thickness of the steel backing mm
1
s Bearing metal thickness mm
2
s Half bearing wall thickness mm
3
s Wall thickness at base of groove mm
4
u Amount of wall thickness reduction for eccentric bearing mm
4 Dimensions and tolerances
4.1 Housing diameter, half bearing outside diameter and crush height
The housing diameter should be manufactured to ISO H6 limits. Thereby 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 a grade 6 tolerance.
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). For the calculation of the effective
interference fit of the half bearings in the housing, see Reference [5].
© ISO 2014 – All rights reserved 3
---------------------- Page: 7 ----------------------
ISO 3548-1:2014(E)
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.
4.2 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
[5]
press fit, reduced by twice the value of the half bearing wall thickness.
NOTE In certain applications it might 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
1
the plane of the joint face. (For guidance of draughtsmen, a is generally specified so that the angle α
1 2
is approximately 25° from the joint face). It is subject to agreement between the user and manufacturer.
Figure 3 — Eccentric bearing bore of half bearing
4 © ISO 2014 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 3548-1:2014(E)
Key
1 crown
2 joint face
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
_= s × (1)
s BL
α,BL u
3,act
1 − sin
α
2
1 − sinα
ss=− UL × (2)
α, 3, act
u
UL
1 − sinα
2
where
BL is the bottom limit of u;
u
UL is the upper limit of u;
u
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
For an example of calculations, see Annex A.
4.3 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).
© ISO 2014 – All rights reserved 5
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ISO 3548-1:2014(E)
4.4 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 part of ISO 3548, 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 of 0,2 mm up to 3 mm. For very
large, thin-walled half bearings, the free spread may be greater but it shall not be such that the half
bearing cannot be fitted into the housing.
Table 2 — Dimensions, tolerances and limit deviations for half bearings with and without
flange
Surface rough-
bc
ness
a
Tolerance or limit deviation for
μm
Flange Dis-
Wall Flange Hous- Bear- Sliding
Housing outside tance Crush
thick- Wall thickness thick- Half bearing width ing ing sur-
f
diameter diam- between height
de
ness ness width back face
e
eter flanges
d s s s B B D B b h Ra Ra
H 3 3 fl 1 2 fl 3 H
preferred without with with- Inte- Assem-
nominal electro- electro- out gral bled
dimen- plated plated flange flange flange
sion antifric- anti- bear- bear-
h
tion layer friction ing ing
g
layer
> ≤
1,5
1,75
0 0 0 0 +0,05 -0,02
a
— 50 0,008 — ±1 0,03 0,8 0,8
-0,05 -0,3 -0,05 -0,12 0 -0,07
2
2,5
1,75
2
0 0 0 0
...
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