SIST-TP ISO/TR 10657:2022

TECHNICAL ISO/TR
REPORT 10657
Second edition
2021-11
Explanatory notes on ISO 76
Notes explicatives sur l'ISO 76
Reference number
© ISO 2021
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 1
4 Basic static load ratings . 3
4.1 General . 3
4.1.1 Basic formula for point contact . 3
4.1.2 Basic formula for line contact . 5
4.2 Basic static radial load rating C for radial ball bearings . 6
0r
4.2.1 Radial and angular contact groove ball bearings . 6
4.2.2 Self-aligning ball bearings . 8
4.3 Basic static axial load rating C for thrust ball bearings . 8
0a
4.4 Basic static radial load rating C for radial roller bearings . 10
0r
4.5 Basic static axial load rating C for thrust roller bearings . 10
0a
5 Static equivalent load .11
5.1 Theoretical static equivalent radial load P for radial bearings . 11
0r
5.1.1 Single-row radial bearings and radial contact groove ball bearings
(nominal contact angle α = 0°) . 11
5.1.2 Double-row radial bearings . 17
5.2 Theoretical static equivalent axial load P for thrust bearings . 18
0a
5.2.1 Single-direction thrust bearings . 18
5.2.2 Double-direction thrust bearings . 21
5.3 Approximate formulae for theoretical static equivalent load . 23
5.3.1 Radial bearings . 23
5.3.2 Thrust bearings . . 24
5.4 Practical formulae of static equivalent load . 24
5.4.1 Radial bearings . 24
5.4.2 Thrust bearings . .28
5.5 Static radial load factor X and static axial load factor Y .29
0 0
5.5.1 Radial bearings .29
5.5.2 Thrust bearings . 33
Annex A (normative) Values for γ, κ and E(κ) .35
Bibliography .38
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
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on the ISO list of patent declarations received (see www.iso.org/patents).
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expressions related to conformity assessment, as well as information about ISO's adherence to
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 4, Rolling bearings, Subcommittee SC 8,
Load ratings and life.
This second edition cancels and replaces the first edition (ISO 10657:1991), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— New subclause 0.4 and 0.5 included with explanations concerning the 2006 edition of ISO 76:2006
and ISO 76/Amd.1:2017;
— Inclusion of Clause 3 for symbols;
— Table 16 and Table 18 amended according to additional values in ISO 76:2006 (values of X and Y at
0 0
contact angles 5° and 10° of angular contact ball bearings).
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
0.1  ISO/R 76:1958
ISO/R 76, Ball and Roller Bearings — Methods of Evaluating Static Load Ratings, was drawn up by
Technical Committee ISO/TC 4, Ball and Roller Bearings.
[2],[3]
ISO/R 76 was based on the studies of A. Palmgren et al . The basic static load ratings were defined
to correspond to a total permanent deformation of rolling element and raceway at the most heavily
stressed rolling element/raceway contact of 0,000 1 of the rolling element diameter. Then the standard
values confined to the basic static load ratings for special inner design rolling bearings were laid down.
ISO/R 76:1958 was approved by 28 (out of a total of 38) member bodies and was then submitted to the
ISO Council, which decided, in December 1958, to accept it as an ISO Recommendation.
0.2  ISO 76:1978
ISO/TC 4 decided to include the revision of ISO/R 76 in its programme of work and ISO/TC 4/SC 8
secretariat was requested to prepare a draft proposal. As a result, the secretariat submitted a draft
[3]
proposal in January 1976.
The draft proposal was accepted by 6 of the 8 members of ISO/TC 4/SC 8. Of the remaining two, Japan
[4]
preferred further study and USA, its counter proposal, document ISO/TC 4/SC 8 N 64 . The draft was
then submitted to the ISO Central Secretariat. After the draft had been approved by the ISO member
bodies, the ISO Council decided in June 1978 to accept it as an International Standard.
ISO 76:1978 adopted the SI unit newton and was revised in total, but without essential changes of
substance. However, values of X and Y for the nominal contact angles 15° and 45° for angular contact
0 0
groove ball bearings were added to the table to calculate the static equivalent radial loads of radial ball
bearings (see ISO 76:1978, Table 2).
0.3  ISO 76:1987
[4]
During the revision of ISO/R 76:1958, USA had in 1975 submitted a counter proposal for the basic
static load ratings based on a calculated contact stress.
The secretariat requested a vote on the revision of the static load ratings based on a contact stress level
in January 1978 and afterward circulated the voted results in June 1978, and the item No. of revision
work had become No. 157 of the programme of work of TC 4.
[5] [6]
ISO/TC 4/SC 8, considering the proposals made in the documents TC 4/SC 8 N 75 and TC 4 N 865 ,
as well as the comments made by TC 4 members and that several SC 8 members expressed a need
for updating ISO 76, agreed to continue its study taking into account the possibility of using either
permanent deformation or stress level as a basis for static load ratings, and ISO/TC 4/SC 8 requested
its secretariat to prepare a new draft. The new draft was intended to be prepared with the principles
and formulae of the document TC 4/SC 8 N 75, and to include levels of contact stress for various rolling
element contact stated to be generally corresponding to a permanent deformation of 0,000 1 of the
rolling element diameter at the centre of the most heavily stressed rolling element/raceway contact.
For roller bearings a stress level of 4 000 MPa was agreed and then ISO/TC 4/SC 8 agreed, by a majority
vote, that static load ratings should correspond to calculated contact stresses of
4 000 MPa for roller bearings,
4 600 MPa for self-aligning ball bearings, and
4 200 MPa for all other ball bearings to which the standard applies.
For these calculated contact stresses, a total permanent deformation occurs at the centre of the most
heavily stressed rolling element/raceway contact, and its deformation is approximately 0,000 1 of the
rolling element diameter.
v
ISO 76 was submitted to the ISO Central Secretariat in 1985, and after it had been approved by the
ISO members, the ISO Council decided in February 1987 to accept it as an International Standard.
Furthermore, ISO/TC 4/SC 8 decided that supplementary background information, regarding the
derivation of formulae and factors given in ISO 76, should be published as a Technical Report. This
Technical report was published as ISO/TR 10657:1991.
An Amendment to ISO 76:1987 that explains the discontinuities in load ratings between radial- and
axial bearings was published as ISO 76:1987/Amd.1:1999.
0.4  ISO 76:2006
A systematic review of ISO 76:1987 was agreed in 2003, based on the prior held balloting process and
documents TC 4/SC 8 N 233 and N 235.
ISO 76:2006 includes editorial adaptations and updates as well as an extension by the static safety
factor S . Furthermore, ISO 76:1987/Amd.1:1999 was integrated and became the informative Annex A
“Discontinuiti
...