ISO 789-2:2018

INTERNATIONAL ISO
STANDARD 789-2
Fourth edition
2018-02
Agricultural tractors — Test
procedures —
Part 2:
Rear three-point linkage lifting
capacity
Tracteurs agricoles — Méthodes d'essai —
Partie 2: Capacité de relevage de l'attelage trois points arrière
Reference number
©
ISO 2018
© ISO 2018
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement units and tolerances . 2
5 General requirements . 2
5.1 Selection. 2
5.2 Running-in and preliminary adjustments . 2
5.3 Manufacturer's instructions . 2
5.4 Repairs . 2
5.5 Preliminary information . 2
5.6 Hydraulic fluid . 3
5.7 Ambient conditions . 3
6 Test procedures . 3
6.1 Common procedures . 3
6.1.1 Secure . 3
6.1.2 Adjustment . . . 3
6.1.3 Throttle lever . 4
6.1.4 Measured maximum performance . 4
6.2 Lift at lower hitch points . 5
6.3 Lift on coupled frame . 6
7 Test report . 6
Bibliography . 7
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
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: 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 2, Common tests.
This fourth edition cancels and replaces the third edition (ISO 789-2:1993), which has been technically
revised for the technical harmonization with OECD Code 2: February 2017.
A list of all the parts in the ISO 789 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 789-2:2018(E)
Agricultural tractors — Test procedures —
Part 2:
Rear three-point linkage lifting capacity
1 Scope
This document specifies test procedures for determining the lifting capacity of rear-mounted three-
point linkage systems:
a) the maximum vertical force which can be exerted by the hydraulic lift at the lower hitch points
throughout their full range of movement;
b) the maximum vertical force which can be exerted by the hydraulic lift, at a point 610 mm to the
rear of the hitch points on a frame attached to the three-point linkage, throughout its full range of
movement.
NOTE 1 A static test provides an adequate comparison between tractors. The test results are used only as a
means of comparing tractors and not as a way of recommending the size of an implement which can be carried by
the tractor.
NOTE 2 This test procedure can be used to determine the lifting capacity of front-mounted three-point hitch
systems.
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 730:2009, Agricultural wheeled tractors — Rear-mounted three-point linkage — Categories 1N, 1, 2N,
2, 3N, 3, 4N and 4
ISO 730:2009/Amd 1:2014, Agricultural wheeled tractors — Rear mounted three-point linkage – Categories
1N, 1, 2N, 2, 3N, 3, 4N and 4 — Amendment 1
ISO 789-13:2018, Agricultural tractors — Test procedures — Part 13: Vocabulary and specimen test report
ISO 3448:1992, Industrial liquid lubricants — ISO viscosity classification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 789-13 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Measurement units and tolerances
The following units and tolerances apply to the maximum value measured:
— rotational frequency, in revolutions per minute (r/min): ± 0,5 %;
— time, in seconds (s): ± 0,2 s;
— distance, in metres or millimetres (m or mm): ± 0,5 %;
— force, in newtons (N): ± 1 %;
— mass, in kilograms (kg): ± 0,5
...