ISO 18955

Railway applications — Suspension components — Rubber diaphragms for pneumatic suspension springs

This international standard applies to suspension diaphragms designed to be fitted on railway vehicles and similar vehicles running on dedicated tracks with permanent guide systems, whatever the type of rail and the running surface. This international standard does not detail other components of pneumatic suspension assemblies or control systems such as air reservoirs, frames, stiffeners, emergency suspension systems or elastic supports (such as series springs), etc., which will affect the diaphragm performance. The international standard specifies terms and definitions,symbols and abbreviated terms, conditions of use, definition of the product, inspection and test methods, marking, definition documents, traceability, qualification and quality surveillance, inspection and quality surveillance.

Applications ferroviaires — Pièces de suspension — Membranes à base d'élastomère pour ressorts pneumatiques de suspension

General Information

• Status: Not Published
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: ISO/TC 269/SC 2 - Rolling stock
• Drafting Committee: ISO/TC 269/SC 2 - Rolling stock
• Current Stage: 6000 - International Standard under publication
• Start Date: 12-Sep-2025
• Completion Date: 13-Sep-2025

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/FDIS 18955
ISO/TC 269/SC 2
Railway applications — Suspension
Secretariat: AFNOR
components — Rubber diaphragms
Voting begins on:
for pneumatic suspension springs
2025-07-17
Applications ferroviaires — Pièces de suspension — Membranes à
Voting terminates on:
base d'élastomère pour ressorts pneumatiques de suspension
2025-09-11
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 18955:2025(en) © ISO 2025

FINAL DRAFT
ISO/FDIS 18955:2025(en)
International
Standard
ISO/FDIS 18955
ISO/TC 269/SC 2
Railway applications — Suspension
Secretariat: AFNOR
components — Rubber diaphragms
Voting begins on:
for pneumatic suspension springs
Applications ferroviaires — Pièces de suspension — Membranes à
Voting terminates on:
base d'élastomère pour ressorts pneumatiques de suspension
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 2025
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 18955:2025(en) © ISO 2025

ii
ISO/FDIS 18955:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 Three-dimensional definition of characteristics. 7
6 Definition documents . 9
6.1 General .9
6.2 Documents to be provided by the customer .9
6.3 Documents to be provided by the supplier .9
7 Conditions of use . 9
7.1 General .9
7.2 Operating temperatures .10
7.3 Environmental conditions . .10
7.4 Operating loading conditions .10
7.5 Recycling .10
8 Definition of the product .10
8.1 General .10
8.1.1 Definition of characteristics .10
8.2 Resistance to operating conditions .11
8.2.1 Low temperature .11
8.2.2 Ozone .11
8.2.3 Cleaning product . 12
8.2.4 Abrasion . 12
8.2.5 Fire behaviour . 12
8.2.6 Other conditions . 12
8.3 Physical characteristics . 12
8.3.1 Materials . 12
8.3.2 Adherence between plies . 12
8.3.3 Pressure resistance . 12
8.3.4 Airtightness . 12
8.3.5 Fatigue resistance . 13
8.3.6 Burst resistance . 13
8.4 Geometrical and dimensional characteristics. 13
8.4.1 Mass . 13
8.4.2 Space envelope and overall dimensions . 13
8.4.3 Appearance of diaphragms in new condition .14
8.4.4 Appearance of diaphragms under extreme deformations .14
8.5 Functional characteristics .14
8.5.1 Stiffnesses .14
8.5.2 Characteristic "internal pressure versus axial static force" .17
8.5.3 Axial isobar characteristic .18
9 Inspection and test methods . 19
9.1 General .19
9.1.1 General test conditions .19
9.1.2 Instrumentation. 20
9.1.3 Definition and preparation of test pieces . 20
9.2 Resistance to operating conditions . 20
9.2.1 Low temperature . 20
9.2.2 Ozone . 20

iii
ISO/FDIS 18955:2025(en)
9.2.3 Cleaning product .21
9.2.4 Abrasion .21
9.2.5 Fire behaviour .21
9.2.6 Other conditions .21
9.3 Physical characteristics .21
9.3.1 Materials .21
9.3.2 Adherence between plies . 22
9.3.3 Pressure resistance . 22
9.3.4 Airtightness . 22
9.3.5 Fatigue resistance . 23
9.3.6 Burst
...

ISO/FDIS 18955
ISO/TC 269/SC 2
ISO/DIS 18955:2024(en)
Secretariat: AFNOR
Date: 2025-07-01
Railway applications — Suspension components — Rubber
diaphragms for pneumatic suspension springs
First edition
Date: 2025-04-14
Applications ferroviaires — Pièces de suspension — Membranes à base d'élastomère pour ressorts
pneumatiques de suspension
FDIS stage
ISO/FDIS 18955:2025(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 copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email: E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland.
iii
ISO/FDIS 18955:2025(en)
Contents page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 4
5 Three-dimensional definition of characteristics. 12
6 Definition documents . 14
6.1 General. 14
6.2 Documents to be provided by the customer . 14
6.3 Documents to be provided by the supplier . 15
7 Conditions of use . 15
7.1 General. 15
7.2 Operating temperatures . 15
7.3 Environmental conditions . 15
7.4 Operating loading conditions . 16
7.5 Recycling . 16
8 Definition of the product . 16
8.1 General. 16
8.2 Resistance to operating conditions . 17
8.3 Physical characteristics . 18
8.4 Geometrical and dimensional characteristics . 19
8.5 Functional characteristics . 20
9 Inspection and test methods . 26
9.1 General. 26
9.2 Resistance to operating conditions . 28
9.3 Physical characteristics . 29
9.4 Geometrical and dimensional characteristics . 33
9.5 Functional characteristics . 34
10 Marking . 47
11 Traceability . 48
12 Supplier production plan qualification . 48
13 Approval and qualification of the product. 48
13.1 Approval . 48
13.2 Qualification . 48
14 Inspection and quality surveillance . 49
Annex A (informative) Types of diaphragm . 50
Annex B (informative) Example of fatigue test programme . 55
Annex C (normative) Qualification procedure . 59
Annex D (informative) Recommended tolerances for characteristics of diaphragms . 61
Bibliography . 62

iv
ISO/FDIS 18955:2025(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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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 269, Railway applications, Subcommittee SC 2,
Rolling stock.
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
ISO/FDIS 18955:2025(en)
Introduction
This document is based on EN 13597:2003.
Designing a suspension diaphragm requires knowledge of the mechanical system of which it forms part.
Specific characteristics are therefore needed for each case, which only the customer can specify.
The requirements of this document are intended to be implemented in conjunction with the conditions for the
supply of air spring suspension diaphragms.
This document is the result of studies and research to improve the performance and quality of rubber
diaphragms for pneumatic suspension springs in order to meet the requirements of railway rolling stock.
This document is designed for involved parties such as railway operators, manufacturers and equipment
suppliers of the railway industry as well as for suppliers of rubber diaphragms for pneumatic suspension
springs.
vi
ISO/FDIS 18955:2025(en)
DRAFT International Standard
Railway applications — Suspension components — Rubber
diaphragms for pneumatic suspension springs
1 Scope
This document specifies the characteristics for suspension diaphragms to achieve, together with applicable
inspection and test methods to be carried out for verification.
An air spring system usually consists of a diaphragm (subject of this document) and additional components
such as either emergency or additional springs, or both, and other assembly parts. This document does not
detail the other components of air suspension or control systems such as air reservoirs, air piping, levelling
system, frames, stiffeners, emergency suspension systems or elastic supports (such as series springs), etc.,
which will affect the diaphragm performance.
This document applies to suspension diaphragms (inflated with air) designed to be fitted on railway vehicles
and similar vehicles running on dedicated tracks with permanent guide systems, whatever the type of rail and
the running surface. These parts are typically made with elastomer, textile fabrics and metallic beads.
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 36, Rubber, vulcanized or thermoplastic — Determination of adhesion to textile fabrics
ISO 48--2, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: Hardness between
10 IRHD and 100 IRHD
ISO 48--4, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 4: Indentation hardness by
durometer method (Shore hardness)
ISO 1431--1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and dynamic
strain testing
ISO 1817, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 2781, Rubber, vulcanized or thermoplastic — Determination of density
ISO 4649, Rubber, vulcanized or thermoplastic –— Determination of abrasion resistance using a rotating
cylindrical drum device
ISO 24087, Rubber, vulcanized — Determination of the glass transition temperature and enthalpy by differential
scanning calorimetry
ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test methods
ISO 80000--3, Quantities and units — Part 3: Space and time
ISO/FDIS 18955:2025(en)
ISO 80000--4, Quantities and units — Part 4: Mechanics
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1 3.1
diaphragm
finished product, comprising rubber, carcass (3.4(3.4)) and beads (3.3(3.3)) for use as part of pneumatic
suspension system
Note 1 to entry: The diaphragm is also known as air bellows, air bag, cushion and membrane.
Note 2 to entry: Different types of diaphragm are illustrated in Annex AAnnex A.
3.1.1 3.1.1
new diaphragm
diaphragm in new condition and never yet used
3.1.2 3.1.2
used diaphragm
diaphragm which has been submitted to a fatigue test, and has, as a result, changed dimensionally
3.2 3.2
out layer of diaphragm
rubber layer located on t
...

PROJET FINAL
Norme
internationale
ISO/FDIS 18955
ISO/TC 269/SC 2
Applications ferroviaires — Pièces
Secrétariat: AFNOR
de suspension — Membranes à
Début de vote:
base d'élastomère pour ressorts
2025-07-17
pneumatiques de suspension
Vote clos le:
2025-09-11
Railway applications — Suspension components — Rubber
diaphragms for pneumatic suspension springs
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
NORMES POUVANT
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
Numéro de référence
ISO/FDIS 18955:2025(fr) © ISO 2025

PROJET FINAL
ISO/FDIS 18955:2025(fr)
Norme
internationale
ISO/FDIS 18955
ISO/TC 269/SC 2
Applications ferroviaires — Pièces
Secrétariat: AFNOR
de suspension — Membranes à
Début de vote:
base d'élastomère pour ressorts
2025-07-17
pneumatiques de suspension
Vote clos le:
2025-09-11
Railway applications — Suspension components — Rubber
diaphragms for pneumatic suspension springs
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
DOCUMENT PROTÉGÉ PAR COPYRIGHT
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
© ISO 2025 INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
NORMES POUVANT
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: [phone]
E-mail: [e-mail]
Web: www.iso.org
Publié en Suisse Numéro de référence
ISO/FDIS 18955:2025(fr) © ISO 2025

ii
ISO/FDIS 18955:2025(fr)
Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d'application . 1
2 Références normatives . 1
3 Termes et définitions . 2
4 Symboles . 3
5 Définition tridimensionnelle des caractéristiques . 7
6 Documents de définition . 9
6.1 Généralités .9
6.2 Documents à fournir par le client .9
6.3 Documents à fournir par le fournisseur .9
7 Conditions d'utilisation . 10
7.1 Généralités .10
7.2 Températures de service .10
7.3 Conditions d’environnement .10
7.4 Conditions de charge en service .10
7.5 Recyclage .10
8 Définition du produit .11
8.1 Généralités .11
8.1.1 Définition des caractéristiques .11
8.2 Résistance aux conditions de service . 12
8.2.1 Basse température. 12
8.2.2 Ozone . 12
8.2.3 Produit de nettoyage . 12
8.2.4 Abrasion . 12
8.2.5 Tenue au feu . 12
8.2.6 Autres conditions . 12
8.3 Caractéristiques physiques . 13
8.3.1 Matériaux . 13
8.3.2 Adhérence entre plis . 13
8.3.3 Résistance à la pression . 13
8.3.4 Étanchéité à l'air . 13
8.3.5 Tenue à la fatigue. 13
8.3.6 Résistance à l'éclatement . 13
8.4 Caractéristiques géométriques et dimensionnelles . 13
8.4.1 Masse . 13
8.4.2 Espace enveloppe et cotes d'encombrement.14
8.4.3 Aspect de la membrane à l'état neuf .14
8.4.4 Aspect des membranes en cas de déformations extrêmes .14
8.5 Caractéristiques fonctionnelles.14
8.5.1 Rigidités .14
8.5.2 Caractéristique «pression interne / force statique axiale » .18
8.5.3 Caractéristique axiale isobare .18
9 Contrôle et méthodes d'essai . 19
9.1 Généralités .19
9.1.1 Conditions générales d'essai .19
9.1.2 Instrumentation. 20
9.1.3 Définition et préparation des éprouvettes . 20
9.2 Résistance aux conditions de service . 20
9.2.1 Basse température. 20
9.2.2 Ozone . 20

iii
ISO/FDIS 18955:2025(fr)
9.2.3 Produit de nettoyage .21
9.2.4 Abrasion .21
9.2.5 Tenue au feu . 22
9.2.6 Autres conditions . 22
9.3 Caractéristiques physiques . 22
9.3.1 Matériaux . 22
9.3.2 Adhérence entre plis . 22
9.3.3 Résistance à la pression . 22
9.3.4 Étanchéité à l'air . 22
9.3.5 Tenue à la fatigue.
...