ISO 6626-2:2024
(Main)Internal combustion engines — Piston rings — Part 2: Coil-spring-loaded oil control rings of narrow width made of cast iron
Internal combustion engines — Piston rings — Part 2: Coil-spring-loaded oil control rings of narrow width made of cast iron
This document specifies the essential dimensional features of coil-spring loaded oil control rings made of cast iron, types DSF-C, SSF, GSF, DSF, SSF-L, DSF-NG and DSF-CNP. It is applicable to those piston rings in sizes 60 mm up to 160 mm, inclusive for reciprocating internal combustion engines for road vehicles and other applications.
Moteurs à combustion interne — Segments de piston — Partie 2: Segments racleurs régulateurs d'huile étroits, en fonte, mis en charge par ressort hélicoïdal
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International
Standard
ISO 6626-2
Third edition
Internal combustion engines —
2024-07
Piston rings —
Part 2:
Coil-spring-loaded oil control rings
of narrow width made of cast iron
Moteurs à combustion interne — Segments de piston —
Partie 2: Segments racleurs régulateurs d'huile étroits, en fonte,
mis en charge par ressort hélicoïdal
Reference number
© ISO 2024
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Overview . 1
5 Piston ring types and designation . 2
5.1 Types DFS-C, DFS-CNP, SSF, GSF, DSF, DSF-NG, and SSF-L — General features and
dimensions .2
5.2 Type DSF-C ─ Coil-spring loaded bevelled edge oil control ring, chromium plated and
profile ground .2
5.2.1 General features and dimensions .2
5.2.2 Designation of a Type DSF-C piston ring in accordance with ISO 6626-2 .3
5.3 Type DSF-CNP ─ Coil-spring loaded bevelled edge oil control ring, chromium plated
not profile ground .4
5.3.1 General features and dimensions .4
5.3.2 Designation of a Type DSF-CNP piston ring in accordance with ISO 6626-2 .4
5.4 Type SSF ─ Coil-spring loaded slotted oil control ring with rectangular groove .5
5.4.1 General features and dimensions .5
5.4.2 Designation of a Type SSF piston ring in accordance with ISO 6626-2 .5
5.5 Type GSF ─ Coil-spring loaded double bevelled oil control ring .5
5.5.1 General features and dimensions .5
5.5.2 Designation of a Type GSF piston ring in accordance with ISO 6626-2 .6
5.6 Type DSF ─ Coil-spring loaded bevelled edge oil control ring .6
5.6.1 General features and dimensions .6
5.6.2 Designation of a Type DSF piston ring in accordance with ISO 6626-2 .7
5.7 Type DSF-NG ─ Coil-spring loaded bevelled edge oil control ring (face geometry similar
to type DSF-C or type DSF-CNP) .7
5.7.1 General features and dimensions .7
5.7.2 Designation of a Type DSF-NG piston ring in accordance with ISO 6626-2 .8
5.8 Type SSF-L ─ Coil-spring loaded slotted oil control ring with rectangular groove at
periphery and V-shaped groove beneath .8
5.8.1 General features and dimensions .8
5.8.2 Designation of a Type SSF-L piston ring in accordance with ISO 6626-2 .9
6 Common features . 9
6.1 Oil drainage by slots or holes .9
6.1.1 Arrangement of slots .9
6.1.2 Slot length .11
6.1.3 Arrangement of holes .11
6.1.4 Diameter and number of holes .11
6.2 Plating thickness — DSF-C and DSF-CNP (coil-spring loaded bevelled edge oil control
ring, chromium plated) .11
6.3 Peripheral edges at gap of chromium plated oil control rings . 12
6.4 Spring groove, slot, and land offsets . 12
7 Coil springs .12
7.1 Types of coil spring . 12
7.2 Latch pin and location of small pitch in the coil spring .14
7.3 Coil spring excursion (extended gap) .14
7.4 Position of coil spring gap and fixing . 15
7.5 Material . 15
8 Tangential force and nominal contact pressure .15
8.1 Tangential force, F . 15
t
iii
8.1.1 Force factors . 15
8.1.2 General tangential force, F . 15
t
8.1.3 Actual tangential force, F , and tolerance .16
t
8.1.4 Normalized tangential force, F .16
N
8.2 Nominal contact pressure, p .16
9 Dimensions .16
Bibliography .31
iv
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).
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 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.
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 22, Road vehicles, Subcommittee SC 34,
Propulsion, powertrain and powertrain fluids.
This third edition cancels and replaces the second edition (ISO 6626-2:2013), which has been technically
revised.
The main changes are as follows:
— classes of nominal contact pressure moved to ISO 6626-1:2024, Annex A and introduced normalized
tangential force;
— verification and correction of figures;
— update of dimension in Tables 8 to 16.
A list of all parts in the ISO 6626 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.
v
Introduction
The ISO 6626 series is one of a series of International Standards dealing with piston rings for reciprocating
internal combustion engines. Others are the ISO 6621 series, ISO 6622, ISO 6623, ISO 6624, ISO 6625, the
ISO 6626
...
FINAL DRAFT
International
Standard
ISO/FDIS 6626-2
ISO/TC 22/SC 34
Internal combustion engines —
Secretariat: ANSI
Piston rings —
Voting begins on:
2024-02-27
Part 2:
Coil-spring-loaded oil control rings
Voting terminates on:
2024-04-23
of narrow width made of cast iron
Moteurs à combustion interne — Segments de piston —
Partie 2: Segments racleurs régulateurs d'huile étroits, en fonte,
mis en charge par ressort hélicoïdal
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 6626-2:2024(en) © ISO 2024
FINAL DRAFT
ISO/FDIS 6626-2:2024(en)
International
Standard
ISO/FDIS 6626-2
ISO/TC 22/SC 34
Internal combustion engines —
Secretariat: ANSI
Piston rings —
Voting begins on:
Part 2:
Coil-spring-loaded oil control rings
Voting terminates on:
of narrow width made of cast iron
Moteurs à combustion interne — Segments de piston —
Partie 2: Segments racleurs régulateurs d'huile étroits, en fonte,
mis en charge par ressort hélicoïdal
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2024
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 6626-2:2024(en) © ISO 2024
ii
ISO/FDIS 6626-2:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Overview . 1
5 Piston ring types and designation . 2
5.1 Types DFS-C, DFS-CNP, SSF, GSF, DSF, DSF-NG, and SSF-L — General features and
dimensions .2
5.2 Type DSF-C ─ Coil-spring loaded bevelled edge oil control ring, chromium plated and
profile ground .2
5.2.1 General features and dimensions .2
5.2.2 Designation of a Type DSF-C piston ring in accordance with ISO 6626-2 .3
5.3 Type DSF-CNP ─ Coil-spring loaded bevelled edge oil control ring, chromium plated
not profile ground .4
5.3.1 General features and dimensions .4
5.3.2 Designation of a Type DSF-CNP piston ring in accordance with ISO 6626-2 .4
5.4 Type SSF ─ Coil-spring loaded slotted oil control ring .5
5.4.1 General features and dimensions .5
5.4.2 Designation of a Type SSF piston ring in accordance with ISO 6626-2 .5
5.5 Type GSF ─ Coil-spring loaded double bevelled oil control ring .5
5.5.1 General features and dimensions .5
5.5.2 Designation of a Type GSF piston ring in accordance with ISO 6626-2 .6
5.6 Type DSF ─ Coil-spring loaded bevelled edge oil control ring .6
5.6.1 General features and dimensions .6
5.6.2 Designation of a Type DSF piston ring in accordance with ISO 6626-2 .7
5.7 Type DSF-NG ─ Coil-spring loaded bevelled edge oil control ring (face geometry similar
to type DSF-C or type DSF-CNP) .7
5.7.1 General features and dimensions .7
5.7.2 Designation of a Type DSF-NG piston ring in accordance with ISO 6626-2 .8
5.8 Type SSF-L ─ Coil-spring loaded slotted oil control ring with 0,4 mm nominal land width .8
5.8.1 General features and dimensions .8
5.8.2 Designation of a Type SSF-L piston ring in accordance with ISO 6626-2 .9
6 Common features . 9
6.1 Oil drainage by slots or holes .9
6.1.1 Arrangement of slots .9
6.1.2 Slot length .11
6.1.3 Arrangement of holes .11
6.1.4 Diameter and number of holes .11
6.2 Plating thickness — DSF-C and DSF-CNP (coil-spring loaded bevelled edge oil control
ring, chromium plated) .11
6.3 Peripheral edges at gap of chromium plated oil control rings . 12
6.4 Spring groove, slot, and land offsets . 12
7 Coil springs .12
7.1 Types of coil spring . 12
7.2 Latch pin and location of small pitch in the coil spring .14
7.3 Coil spring excursion (extended gap) .14
7.4 Position of coil spring gap and fixing . 15
7.5 Material . 15
8 Tangential force and nominal contact pressure .15
8.1 Tangential force, F . 15
t
8.1.1 Force factors . 15
iii
ISO/FDIS 6626-2:2024(en)
8.1.2 General tangential force, F . 15
t
8.1.3 Actual tangential force, F , and tolerance .16
t
8.1.4 Normalized tangential force, F .16
N
8.2 Nominal contact pressure, p .16
9 Dimensions .16
Bibliography .31
iv
ISO/FDIS 6626-2:2024(en)
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).
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 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
...
ISO /FDIS 6626-2:2023(E)
ISO /TC 22/SC 34/WG 4
Date: 2023-10-12
Secretariat: DIN ANSI
Date: 2024-02-13
Internal combustion engines — Piston rings — —
Part 2:
Coil-spring -loaded oil control rings of narrow width made of cast
iron
Moteurs à combustion interne — Segments de piston —
Partie 2: Segments racleurs régulateurs d'huile étroits, en fonte, mis en charge par ressort hélicoïdal
FDIS stage
ISO/FDIS 6626-2:2023(E2024(en)
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'sISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CP 401 • Ch. de Blandonnet 8
CH-12111214 Vernier, Geneva 20
Tel.Phone: + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail: copyright@iso.org
Web www.iso.org
Website: www.iso.org
Published in Switzerland.
ii © ISO 2023 – All rights reserved
ii
ISO/FDIS 6626-2:2023(E2024(en)
Contents
Foreword . vii
Introduction. viii
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Overview .1
5 Piston ring types and designation .2
5.1 Types DFS-C, DFS-CNP, SSF, GSF, DSF, DSF-NG, and SSF-L — General features and dimensions .2
5.2 Type DSF-C ─ Coil-spring loaded bevelled edge oil control ring, chromium plated and profile ground .3
5.2.1 General features and dimensions .3
5.2.2 Designation of a Type DSF-C piston ring in accordance with ISO 6626-2 .5
5.3 Type DSF-CNP ─ Coil-spring loaded bevelled edge oil control ring, chromium plated not profile ground
5.3.1 General features and dimensions .5
5.3.2 Designation of a Type DSF-CNP piston ring in accordance with ISO 6626-2 .7
5.4 Type SSF ─ Coil-spring loaded slotted oil control ring .7
5.4.1 General features and dimensions .7
5.4.2 Designation of a Type SSF piston ring in accordance with ISO 6626-2 .9
5.5 Type GSF ─ Coil-spring loaded double bevelled oil control ring .9
5.5.1 General features and dimensions .9
5.5.2 Designation of a Type GSF piston ring in accordance with ISO 6626-2 . 11
5.6 Type DSF ─ Coil-spring loaded bevelled edge oil control ring . 11
5.6.1 General features and dimensions . 11
5.6.2 Designation of a Type DSF piston ring in accordance with ISO 6626-2 . 13
5.7 Type DSF-NG ─ Coil-spring loaded bevelled edge oil control ring (face geometry similar to type DSF-C
or type DSF-CNP) . 13
5.7.1 General features and dimensions . 13
5.7.2 Designation of a Type DSF-NG piston ring in accordance with ISO 6626-2 . 15
5.8 Type SSF-L ─ Coil-spring loaded slotted oil control ring with 0,4 mm nominal land width . 15
5.8.1 General features and dimensions . 15
5.8.2 Designation of a Type SSF-L piston ring in accordance with ISO 6626-2 . 17
6 Common features . 17
6.1 Oil drainage by slots or holes . 17
6.1.1 Arrangement of slots . 17
6.1.2 Slot length . 20
6.1.3 Arrangement of holes . 20
iii
ISO/FDIS 6626-2:2023(E2024(en)
6.1.4 Diameter and number of holes . 21
6.2 Plating thickness — DSF-C and DSF-CNP (coil-spring loaded bevelled edge oil control ring, chromium
plated) . 21
6.3 Peripheral edges at gap of chromium plated oil control rings . 22
6.4 Spring groove, slot, and land offsets. 22
7 Coil springs . 23
7.1 Types of coil spring . 23
7.2 Latch pin and location of small pitch in the coil spring . 25
7.3 Coil spring excursion (extended gap) . 26
7.4 Position of coil spring gap and fixing . 26
7.5 Material . 26
8 Tangential force and nominal contact pressure . 27
8.1 Tangential force, F .27
t
8.1.1 Force factors . 27
8.1.2 General tangential force, F . 27
t
8.1.3 Actual tangential force, F , and tolerance . 27
t
8.1.4 Normalized tangential force, F . 28
N
8.2 Nominal contact pressure, p . 28
9 Dimensions . 28
Bibliography . 48
Foreword . 5
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Overview . 6
5 Piston ring types and designation . 6
5.1 Types DSF-C, SSF, GSF, DSF, SSF-L, DSF-NG and DSF-CNP 6
5.1.1 General features and dimensions 6
5.2 Type DSF-C ─ Coil-spring loaded bevelled edge oil control ring, chromium plated and profile ground 8
iv © ISO 2023 – All rights reserved
iv
ISO/FDIS 6626-2:2023(E2024(en)
5.2.1 General features and dimensions 8
5.2.2 Designation of a Type DSF-C piston ring in accordance with ISO 6626-2 8
5.3 Type DSF-CNP ─ Coil-spring loaded bevelled edge oil control ring, chromium plated not profile ground 9
5.3.1 General features and dimensions 9
5.3.2 Designation of a Type DSF-CNP piston ring in accordance with ISO 6626-2 9
5.4 Type SSF ─ Coil-spring loaded slotted oil control ring 10
5.4.1 General features and dimensions 10
5.4.2 Designation of a Type SSF piston ring in accordance with ISO 6626-2 10
5.5 Type GSF ─ Coil-spring loaded double bevelled oil control ring 11
5.5.1 General features and dimensions 11
5.5.2 Designation of a Type GSF piston ring in accordance with ISO 6626-2 11
5.6 Type DSF ─ Coil-spring loaded bevelled edge oil control ring 12
5.6.1 General features and dimensions 12
5.6.2 Designation of a Type DSF piston ring in accordance with ISO 6626-2 12
5.7 Type DSF-NG ─ Coil-spring loaded bevelled edge oil control ring (face geometry similar to type DSF-C)
5.7.1 General features and dimensions 13
5.7.2 Designation of a Type DSF-NG piston ring in accordance with ISO 6626-2 13
5.8 Type SSF-L ─ Coil-spring loaded slotted oil control ring with 0,4 mm nominal land width 14
5.8.1 General features and dimensions 14
5.8.2 Designation of a Type SSF-L piston ring in accordance with ISO 6626-2 14
6 Common features .15
6.1 Oil drainage by slots or holes 15
6.1.1 Arrangement of slots 15
6.1.2 Slot length 15
6.1.2.1 Standard slot length 15
6.1.2.2 Reduced slot length – Code WK 15
6.1.3 Arrangement of holes 16
6.1.4 Diameterand number of holes 16
6.2 Plating thickness — DSF-C and DSF-CNP (coil-spring loaded bevelled edge oil control ring, chromium plated)
6.3 Peripheral edges at gap of chromium plated oil control rings 17
7 Coil springs .17
7.1 Types of coil spring 17
7.2 Coil spring excursion (extended gap) 19
7.3 Position of coil spring gap and fixing 19
7.4 Material 19
8 Tangential force and nominal contact pressure .20
8.1 Tangential force, Ft 20
...
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