ISO/FDIS 13284
(Main)Industrial trucks — Fork arm extensions and telescopic fork arms — Technical characteristics and strength requirements
Industrial trucks — Fork arm extensions and telescopic fork arms — Technical characteristics and strength requirements
This document specifies technical characteristics and strength requirements for fork arm extensions and telescopic fork arms for industrial trucks. It applies to fork arm extensions and telescopic fork arms, as defined in ISO 5053‑2, designed for use on industrial trucks and stacking lift trucks, as defined in ISO 5053‑1, having fork arm carriers and, in the case of fork arm extensions, fork arms conforming to ISO 2330. This document does not apply to integral transverse telescopic fork devices or scissor-action reach devices.
Chariots de manutention — Extensions de bras de fourche et bras de fourche télescopiques — Caractéristiques techniques et prescriptions de résistance
Le présent document spécifie les caractéristiques techniques et les prescriptions de résistance pour les extensions de bras de fourche et les bras de fourche télescopiques pour les chariots de manutention. Il s'applique aux extensions de bras de fourche et aux bras de fourche télescopiques, tel que défini dans l'ISO 5053-2, conçus pour une utilisation sur des chariots de manutention et des chariots élévateurs gerbeurs, tels que définis dans l'ISO 5053-1, ayant un tablier porte-équipement et dans le cas des extensions de bras de fourche, des bras de fourche conformes à l'ISO 2330. Le présent document ne s'applique pas aux dispositifs à fourches télescopiques transversales intégraux ou des dispositifs à ciseaux.
General Information
- Status
- Not Published
- Technical Committee
- ISO/TC 110/SC 2 - Safety of powered industrial trucks
- Drafting Committee
- ISO/TC 110/SC 2/WG 1 - Fork arms
- Current Stage
- 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
- Start Date
- 30-Jan-2026
- Completion Date
- 30-Jan-2026
Relations
- Effective Date
- 04-Nov-2023
Overview
ISO/FDIS 13284 establishes comprehensive technical characteristics and strength requirements for fork arm extensions and telescopic fork arms used with industrial trucks. Developed by ISO Technical Committee ISO/TC 110 and Subcommittee SC 2, this standard applies to fork attachments designed according to ISO 5053-1 and ISO 5053-2, primarily handling safe load management on stacking lift trucks and industrial trucks with fork arm carriers complying with ISO 2330. Notably, the standard excludes integral transverse telescopic fork devices and scissor-action reach devices.
This standard reflects the latest industry consensus on safety factors, load capacities, and design parameters to ensure operational efficiency and reduce risk of mechanical failure during material handling operations.
Key Topics
Scope of Fork Arm Extensions and Telescopic Fork Arms
- Defines the types of fork extensions (closed rectangular or open inverted-channel cross-sections)
- Addresses temporary extension usage vs. permanent telescopic fork arms
- Specifies exclusion criteria: integral transverse and scissor-action reach devices
Technical and Strength Requirements
- Rated capacity and rated load center distances for fork arms, extensions, and telescopic arms
- Detailed load testing requirements in both fully retracted and fully extended positions
- Safety factors mandated for design and testing reliability
- Retaining system efficacy to prevent accidental disengagement of extensions
- Lateral clearance limits with specified upper and lower bounds for extensions
Verification and Testing Procedures
- Standardized test protocols for evaluating fork arm strength and durability
- Procedures to verify compliance with load-bearing and safety criteria
- Documentation of test results for conformity assessment
Marking and User Information
- Mandatory marking requirements for traceability and safety compliance
- User instructions to optimize safe operation and maintenance of fork extensions and telescopic arms
Applications
ISO/FDIS 13284 is critical for manufacturers, safety inspectors, and end users of industrial trucks involved in logistics, warehousing, and materials handling. Its application enhances:
Industrial Truck Safety
By complying with stringent strength and load criteria, the standard reduces the risk of accidents caused by fork failures or improper load management.Material Handling Efficiency
Telescopic fork arms offer flexible load handling by adjusting fork lengths, ideal for stacking and transporting palletized goods of varying sizes. Fork arm extensions provide a safe temporary solution to extend reach without replacing entire fork sets.Quality Assurance for Manufacturers
Provides clear design and testing guidelines that help maintain consistent product quality, ensuring that all forks and extensions meet international safety standards.Regulatory Compliance
Supports enterprises in meeting workplace safety and equipment standards stipulated by occupational safety authorities around the world.
Related Standards
ISO 5053-1 and ISO 5053-2: Define industrial truck and stacking lift truck classifications and fork arm carrier specifications, foundational to this standard’s scope.
ISO 2330: Specifies dimensions and classifications of fork arms, relevant for ensuring compatibility with extensions studied in ISO/FDIS 13284.
ISO 3691 Series: Covers safety requirements for industrial trucks, complementing fork component standards with overarching vehicle safety norms.
ISO/IEC Directives, Part 1 & 2: Outline the procedural framework ISO follows to develop international standards, providing context on document maintenance and approval.
By integrating ISO/FDIS 13284, stakeholders advance the safety, reliability, and adaptability of industrial truck fork attachments, contributing to safer workplaces and optimized material handling operations globally. For further information and updates, visit ISO official site.
ISO/FDIS 13284 - Industrial trucks — Fork arm extensions and telescopic fork arms — Technical characteristics and strength requirements Released:16. 01. 2026
REDLINE ISO/FDIS 13284 - Industrial trucks — Fork arm extensions and telescopic fork arms — Technical characteristics and strength requirements Released:16. 01. 2026
Frequently Asked Questions
ISO/FDIS 13284 is a draft published by the International Organization for Standardization (ISO). Its full title is "Industrial trucks — Fork arm extensions and telescopic fork arms — Technical characteristics and strength requirements". This standard covers: This document specifies technical characteristics and strength requirements for fork arm extensions and telescopic fork arms for industrial trucks. It applies to fork arm extensions and telescopic fork arms, as defined in ISO 5053‑2, designed for use on industrial trucks and stacking lift trucks, as defined in ISO 5053‑1, having fork arm carriers and, in the case of fork arm extensions, fork arms conforming to ISO 2330. This document does not apply to integral transverse telescopic fork devices or scissor-action reach devices.
This document specifies technical characteristics and strength requirements for fork arm extensions and telescopic fork arms for industrial trucks. It applies to fork arm extensions and telescopic fork arms, as defined in ISO 5053‑2, designed for use on industrial trucks and stacking lift trucks, as defined in ISO 5053‑1, having fork arm carriers and, in the case of fork arm extensions, fork arms conforming to ISO 2330. This document does not apply to integral transverse telescopic fork devices or scissor-action reach devices.
ISO/FDIS 13284 is classified under the following ICS (International Classification for Standards) categories: 53.060 - Industrial trucks. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO/FDIS 13284 has the following relationships with other standards: It is inter standard links to ISO 13284:2022. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO/FDIS 13284 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
FINAL DRAFT
International
Standard
ISO/TC 110/SC 2
Industrial trucks — Fork arm
Secretariat: SIS
extensions and telescopic fork arms
Voting begins on:
— Technical characteristics and
2026-01-30
strength requirements
Voting terminates on:
2026-03-27
Chariots de manutention — Extensions de bras de fourche et
bras de fourche télescopiques — Caractéristiques techniques et
prescriptions de résistance
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
FINAL DRAFT
International
Standard
ISO/TC 110/SC 2
Industrial trucks — Fork arm
Secretariat: SIS
extensions and telescopic fork arms
Voting begins on:
— Technical characteristics and
strength requirements
Voting terminates on:
Chariots de manutention — Extensions de bras de fourche et
bras de fourche télescopiques — Caractéristiques techniques et
prescriptions de résistance
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 2026
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
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Requirements for rated capacity and rated load centre distance . 2
5.1 Fork arm .2
5.2 Fork arm extension .3
5.3 Telescopic fork arm .3
5.4 Safety factor .3
6 Requirements for fork arm extensions. 3
6.1 Length .3
6.2 Accidental disengagement .3
6.3 Test/design load .3
6.4 Fork arm extension retaining system .4
6.5 Lateral clearance .5
7 Requirements for telescopic fork arms . 5
7.1 General .5
7.2 Test load in fully retracted mode with pallet stop .5
7.3 Test load in fully retracted mode without pallet stop .6
7.4 Test load in fully extended mode with pallet stop .7
7.5 Test load in fully extended mode without pallet stop .7
8 Verification and testing . 8
8.1 General .8
8.2 Procedure .8
8.3 Results . .8
9 Information for use . 9
9.1 Fork arm extensions .9
9.2 Telescopic fork arms .9
10 Marking . . 9
10.1 Fork arm extensions .9
10.2 Telescopic fork arms .10
Annex A (informative) Buckling in fork arm extensions .11
Bibliography .12
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 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 110, Industrial trucks, Subcommittee SC 2,
Safety of powered industrial trucks.
This third edition cancels and replaces the second edition (ISO 13284:2022), which has been technically
revised.
The main changes are as follows:
— the lateral clearance for fork extensions has been changed to include upper and lower limits.
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
This document was developed in response to worldwide demand for specifications for fork arm extensions
and telescopic fork arms.
Fork arm extensions are used as a temporary means of extending the effective blade length of fork arms
on industrial trucks. They are available with either a closed rectangular cross-section or an open inverted-
channel cross-section.
Whenever possible, longer forks should be used instead of fork arm extensions.
Telescopic fork arms replace standard fork arms and provide the truck operator with the means of adjusting
the fork arm blade length. They are available either as simple variable-length fork arms for handling loads
of varying dimensions or for reaching out or retracting palletized loads in double-deep stacking and de-
stacking operations.
v
FINAL DRAFT International Standard ISO/FDIS 13284:2026(en)
Industrial trucks — Fork arm extensions and telescopic fork
arms — Technical characteristics and strength requirements
1 Scope
This document specifies technical characteristics and strength requirements for fork arm extensions and
telescopic fork arms (as defined in ISO 5053-2) for industrial trucks (as defined in ISO 5053-1). It applies to
fork arm extensions and telescopic fork arms that are designed for use on industrial trucks that have fork
arm carriers and, in the case of fork arm extensions, fork arms that conform to ISO 2330.
This document does not apply to integral transverse telescopic fork devices or scissor-action reach devices.
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 ed
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ISO/DISFDIS 13284:2025(en)
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ISO /TC 110/SC 2/WG 1
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Date: 2025-11-18 .
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Secretariat: SIS
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Date: 2026-01-15
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Industrial trucks — Fork arm extensions and telescopic fork arms —
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Technical characteristics and strength requirements
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Chariots de manutention — Extensions de bras de fourche et bras de fourche télescopiques — Caractéristiques Style Definition
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techniques et prescriptions de résistance
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St l D fi iti
ISO/CDFDIS 13284:20252026(en)
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© ISO 2026
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication Formatted: Default Paragraph Font
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
E-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
Formatted: German (Germany)
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ii © ISO 2025 – All rights reserved
ii
ISO/DISFDIS 13284:20252026(en)
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Contents
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Foreword . v
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Introduction . vi
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1 Scope . 1
stops: Not at 14.02 cm
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Requirements for rated capacity and rated load centre distance . 2
5.1 Fork arm . 2
5.2 Fork arm extension . 2
5.3 Telescopic fork arm . 3
5.4 Safety factor . 3
6 Requirements for fork arm extensions . 3
6.1 Length. 3
6.2 Accidental disengagement . 3
6.3 Test/design load . 3
6.4 Fork arm extension retaining system . 4
6.5 Lateral clearance . 5
7 Requirements for telescopic fork arms . 6
7.1 General. 6
7.2 Test load in fully retracted mode with pallet stop . 6
7.3 Test load in fully retracted mode without pallet stop . 8
7.4 Test load in fully extended mode with pallet stop . 9
7.5 Test load in fully extended mode without pallet stop . 10
8 Verification and testing . 11
8.1 General. 11
8.2 Procedure . 12
8.3 Results . 12
9 Information for use . 12
9.1 Fork arm extensions . 12
9.2 Telescopic fork arms . 13
10 Marking . 13
10.1 Fork arm extensions . 13
10.2 Telescopic fork arms . 13
Annex A (informative) Buckling in fork arm extensions . 15
Bibliography . 17
Foreword . iv
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Introduction . v
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1 Scope . 1
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2 Normative references . 1
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3 Terms and definitions . 1
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4 Symbols . 2
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iii
ISO/CDFDIS 13284:20252026(en)
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5 Requirements for rated capacity and rated load centre distance . 2
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5.1 Fork arm . 2
5.2 Fork arm extension . 3
5.3 Telescopic fork arm . 3
5.4 Safety factor . 3
6 Requirements for fork arm extensions . 3
6.1 Length. 3
6.2 Accidental disengagement . 3
6.3 Test / design load . 3
6.4 Fork arm extension retaining system . 4
6.5 Lateral clearance . 5
7 Requirements for telescopic fork arms . 5
7.1 General. 5
7.2 Test load in fully retracted mode with pallet stop . 5
7.3 Test load in fully retracted mode without pallet stop . 6
7.4 Test load in fully extended mode with pallet stop . 7
7.5 Test load in fully extended mode without pallet stop . 7
8 Verification and Testing . 8
8.1 General. 8
8.2 Procedure . 8
8.3 Results . 9
9 Information for use . 9
9.1 Fork arm extensions . 9
9.2 Telescopic fork arms . 9
10 Marking . 10
10.1 Fork arm extensions . 10
10.2 Telescopic fork arms . 10
Annex A (informative) . 11
Buckling in fork arm extensions . 11
Bibliography . 12
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iv © ISO 2025 – All rights reserved
iv
ISO/DISFDIS 13284:20252026(en)
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Formatted: Font: Bold, English (United Kingdom)
Formatted: Font: Bold, English (United Kingdom)
Foreword
Formatted: Font: Bold
ISO (the International Organization for Standardization) is a worldwide federation of national standards
Formatted: HeaderCentered, Left
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
Formatted: Adjust space between Latin and Asian text,
ISO technical committees. Each member body interested in a subject for which a technical committee has been
Adjust space between Asian text and numbers
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).
Formatted: English (United Kingdom)
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.
Formatted: English (United Kingdom)
This document was prepared by Technical Committee ISO/TC 110, Industrial trucks, Subcommittee SC 2,
Formatted: Adjust space between Latin and Asian text,
Safety of powered industrial trucks.
Adjust space between Asian text and numbers
This third edition cancels and replaces the second edition (ISO 13284:2022), which has been technically
Formatted: Default Paragraph Font
revised.
Formatted: Default Paragraph Font
Formatted: Default Paragraph Font
The main changes are as follows:
— the lateral clearance for fork extensions has been changed to include upper and lower limits.
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
Any feedback or questions on this document should be directed to the user’s national standards body. A
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
complete listing of these bodies can be found at www.iso.org/members.html.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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v
ISO/CDFDIS 13284:20252026(en)
Formatted: Font: Bold
Formatted: Font: Bold
Formatted: Font: Bold
Introduction
Formatted: HeaderCentered
This document was developed in response to worldwide demand for specifications for fork arm extensions
and telescopic fork arms.
Fork arm extensions are used as a temporary means of extending the effective blade length of fork arms on
industrial trucks. They are available with either a closed rectangular cross-section or an open inverted-
channel cross-section.
Whenever possible, longer forks should be used instead of fork arm extensions.
Telescopic fork arms replace standard fork arms and provide the truck operator with the means of adjusting
the fork arm blade length. They are available either as simple variable-length fork arms for handling loads of
varying dimensions or, alternatively, for reaching out or retracting palletized loads in double-deep stacking
and de-stacking operations.
Formatted: FooterPageRomanNumber
vi © ISO 2025 – All rights reserved
vi
DRAFT International Standard ISO/DIS 13284:2025(en)
Industrial trucks — Fork arm extensions and telescopic fork arms —
Technical characteristics and strength requirements
1 Scope
This document specifies technical characteristics and strength requirements for fork arm extensions and
Formatted: Body Text, Space Before: 0 pt, After: 0 pt
telescopic fork arms (as defined in ISO 5053-2) for industrial trucks (as defined in ISO 5053-1). It applies to
fork arm extensions and telescopic fork arms that are designed for use on industrial trucks that have fork arm
carriers and, in the case of fork arm extensions, fork arms that conform to ISO 2330.
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers
This document does not apply to integral transverse telescopic fork devices or scissor-action reach devices.
Formatted: Default Paragraph Font
2 Normative references Formatted: Default Paragraph Font
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The following documents are referred to in the text in such a way that some or all of their content constitutes
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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.
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
ISO 3691--1, Industrial trucks — Safety requirements and verification — Part 1: Self-propelled industrial
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
trucks, other than driverless trucks, variable-reach trucks and burden-carrier trucks 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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ISO 3691--2, Industrial trucks — Safety requirements and verification — Part 2: Self-propelled variable-reach
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trucks
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ISO 2330:2002, Fork-lift trucks — Fork arms — Technical characteristics and testing
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3 Terms and definitions
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For the purposes of this document, the following terms and definitions apply.
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
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— ISO Online browsing platform: available at https://www.iso.org/obp
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Formatted: English (United States)
— IEC Electropedia: available at https://www.electropedia.org/
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3.1
and Asian text, Adjust space between Asian text and
numbers
parent fork arm
fork arm having the rated capacity at the rated load centre distance, blade length and blade cross-section for
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which a fork arm extension is specifically designed
Asian text, Adjust space between Asian text and
numbers
3.2
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test load
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F and F test/design load for each open-section and closed-section extension, F , and test/design load for
EX T EX
and Asian text, Adjust space between Asian text and
each telescopic fork arm, F , applied load for verifying the strength of fork arm extension and telescopic fork
T
numbers
arms, respectively, by physical testing or calculation
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spacing: single, Tab stops: Not at 17.2 cm
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ISO CD/FDIS 13284:20252026(en)
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4 Symbols
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b fork arm blade width mm
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C rated capacity of each parent fork arm kg Formatted
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CE rated capacity of each fork arm extension kg .
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C rated capacity of each telescopic fork arm in the fully retracted mode kg .
R
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C rated capacity for each telescopic fork arm in the fully extended mode kg
R-EXT
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D rated load centre distance of each parent fork arm mm
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DE rated load centre distance of each fork arm extension mm
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D rated load centre distance of each telescopic fork arm in the fully retracted mode mm
R
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D rated load centre distance for each telescopic fork arm in the fully extended mode mm
R-EXT
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FEX test/design load for each open-section and closed-section extension N
Formatted
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FT test/design load for each telescopic fork arm N
Formatted
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l blade length of the parent fork arm or of the fully retracted telescopic arm mm
Formatted
...
l fork extension length mm
f Formatted
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l1 blade length of the fork arm extension or of the fully extended telescopic arm mm
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l = 0,9 l − l mm .
2 1
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M stress modulator -–
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R safety factor -–
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S total lateral clearance between the parent fork and the fork arm extension mm
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Y actual material yield strength of extension material MPa
a
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Y minimum specified material yield strength of extension material MPa
m
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Z section modulus of the extension of the fork arm tip mm
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σ buckling strength in the fork arm extension MPa
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g acceleration due to gravity (9,8) m/s
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P pallet stop distance for each telescopic fork arm in fully retracted mode mm
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5 Requirements for rated capacity and rated load centre distance
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5.1 Fork arm
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The rated capacity (, C), and rated load centre distance (, D), for the parent fork arm of quantity production
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shall conform with ISO 3691--1 and ISO 3691--2. .
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5.2 Fork arm extension
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The rated capacity (, C ), and rated load centre distance (, D ), for each fork arm extension shall be proportional Formatted
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to the rated capacity (, C), and rated load centre distance (, D), for the parent fork arm, as given in Formula (1):
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Formula (1):
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2 © ISO 2025 – All rights reserved .
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ISO/DISFDIS 13284:20252026(en)
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𝐶𝐶⋅𝐷𝐷
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E
𝐷𝐷
E
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𝐶𝐶⋅𝐷𝐷
𝐶𝐶 ≤ (1)
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5.3 Telescopic fork arm
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The rated capacity (, CR), and rated load centre distance (, DR), for each telescopic fork arm shall both be as
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specified in ISO 3691--1 and ISO 3691--2, in kilograms and millimetres respectively, when the telescopic fork
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arm is in the fully retracted mode.
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In extended mode, the rated capacity and load centre distance shall be specified by the manufacturer.
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5.4 Safety factor
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The safety factor, R, shall be in accordance with ISO 2330:2002, 6.1. Formatted: Default Paragraph Font
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6 Requirements for fork arm extensions
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