ISO 20383:2025

International
Standard
ISO 20383
Second edition
Tractors and machinery for
2025-10
agriculture — Speed Identification
Sign (SIS)
Tracteurs et matériels agricoles et forestiers — Signe
d'identification de la vitesse (SIV)
Reference number
© ISO 2025
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 .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4 Dimensions . 2
5 Materials, performance and test requirements . 3
5.1 Performance requirements .3
5.2 Adhesion .3
5.3 Colour measurement .3
6 Positioning . . 3
6.1 Rear facing SIS .3
6.2 Forward facing SIS .4
6.3 Towed equipment combinations .4
7 Operating instructions for towing vehicles . 4
Bibliography . 6

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 23, Tractors and machinery for agriculture and
forestry, Subcommittee SC 4, Tractors.
This second edition cancels and replaces the first edition (ISO 20383:2017), which has been technically
revised.
The main changes are as follows.
— The term “forestry” was removed from the title.
— In the introduction, the term “implement of husbandry/agricultural equipment” has been replaced with
the term “agricultural field equipment” as defined in ISO 12934.
— In the last sentence of Clause “1 Scope” the list of terms “self-propelled, semi-integral and towed
equipment has been replaced with “agricultural field equipment” as defined in ISO 12934.
— In Clause 1, subclause 6.1.1 and subclause 6.1.3, the term “agricultural vehicle” has been replaced with
“agricultural field equipment” as defined in ISO 12934.
— In 3.2, the definition of “implement of husbandry” has been replaced with the definition of “agricultural
field equipment” according to ISO 12934.
— In Figure 1 of subclause 4.1, the depiction of the symmetrical tolerance has been corrected according to
ISO 129-1.
— In 4.4, the explanation in parenthesis "(e.g. 45 to 50)" has been corrected to "(e.g. 40, 45, 50)".
— ISO 12934 has been added to the Bibiliography.
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
Agricultural field equipment operations include the transport of commodities and equipment from the field
sites to farmsteads, storage facilities and gathering points for movement by mass transit systems. Equipment
often moves between farmsteads and field sites that are not contiguous. Transport may involve moving on
public roads (infrastructure) that permit faster ground speeds than that which is used in the fields or within
the design considerations of the equipment. Design approaches have been identified to permit selected
equipment to move at faster ground speeds in transport configurations. This doc
...