ISO 789-9:2018

Agricultural tractors - Test procedures - Part 9: Power tests for drawbar

ISO 789-9:2018 specifies test procedures for determining the power available at the drawbar on agricultural tractors of the wheeled, track-laying or semi-track-laying type.

Tracteurs agricoles — Méthodes d'essai — Partie 9: Essais de puissance à la barre d'attelage

Kmetijski traktorji - Preskusne metode - 9. del: Preskus vlečne moči

General Information

• Status: Published
• Publication Date: 21-Feb-2018
• ICS: 65.060.10 - Agricultural tractors and trailed vehicles
• Technical Committee: ISO/TC 23/SC 2 - Common tests
• Drafting Committee: ISO/TC 23/SC 2/WG 6 - Test procedures for agricultural tractors
• Current Stage: 9093 - International Standard confirmed
• Start Date: 29-Jul-2024
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO 789-9:2020 - Agricultural tractors - Test procedures - Part 9: Power tests for drawbar

Relations

• Revises: ISO 789-9:1990 - Agricultural tractors - Test procedures - Part 9: Power tests for drawbar
• Effective Date: 28-Feb-2009
• Revises: ISO 789-9:1990/Amd 1:1993 - Agricultural tractors - Test procedures - Part 9: Power tests for drawbar - Amendment 1
• Effective Date: 28-Feb-2009

Overview

ISO 789-9:2018 - "Agricultural tractors - Test procedures - Part 9: Power tests for drawbar" specifies standardized test procedures to determine the power available at the drawbar of agricultural tractors of wheeled, track‑laying or semi‑track‑laying types. This second edition (2018) harmonizes with OECD Code 2 (2017) and defines methods, measurement units, tolerances and reporting requirements for drawbar power and associated fuel‑use measurements.

Key Topics and Requirements

• Scope and selection: Tests apply to production tractors; manufacturer and test body collaborate on tractor selection. A manufacturer’s representative is required during testing.
• Measurement units & tolerances: Specified accuracies for rotational speed (±0.5 %), force (±1 %), fuel consumption (±1 %), temperatures and other key quantities.
• Pre-test conditions: New, run‑in tractors per manufacturer instructions; adjustments allowed before testing but not during.
• Fuels & lubricants: Use commercially available products conforming to manufacturer or national/international standards. Fuel consumption measurement during drawbar tests is mandatory.
• Diesel particulate filters: Regeneration may be performed before testing; tests are paused if regeneration begins during a run.
• Auxiliary equipment: Accessories may only be disconnected if allowed by the operator’s manual; variable parasitic loads must be accounted for in reports.
• Ambient & tractor conditions: No atmospheric corrections are made; atmospheric pressure should not be less than 96.6 kPa and ambient temperature around 20 °C ± 15 °C. Tyre or track tread height must be at least 65% of new as measured per Annex A.
• Slip measurement: Wheel/track slip is defined and measured as part of drawbar testing; procedures for maximum power, fuel consumption at nominal speeds, and continuous tests are provided.
• Reporting: A standardized test report is required (see ISO 789‑13 vocabulary and specimen report).

Applications and Users

ISO 789-9 is used by:

• Tractor manufacturers for performance verification and R&D
• Third‑party test laboratories and certification bodies conducting conformity or comparative testing
• Agricultural equipment designers and implement manufacturers checking compatibility with drawbar power ratings
• Research institutions analyzing tractor performance and fuel efficiency

Practical uses include establishing performance claims, comparing models, validating transmission and traction systems, and supporting product documentation.

Related Standards

• ISO 789 series (other parts cover related tractor tests)
• ISO 789-13:2018 - Vocabulary and specimen test report (normative reference)
• Harmonized with OECD Code 2: 2017

Keywords: ISO 789-9, drawbar power, agricultural tractors, drawbar tests, test procedures, fuel consumption, tyre slip, test report.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2020
Kmetijski traktorji - Preskusne metode - 9. del: Preskus vlečne moči
Agricultural tractors - Test procedures - Part 9: Power tests for drawbar
Tracteurs agricoles - Méthodes d'essai - Partie 9: Essais de puissance à la barre
d'attelage
Ta slovenski standard je istoveten z: ISO 789-9:2018
ICS:
65.060.10 Kmetijski traktorji in prikolice Agricultural tractors and
trailed vehicles
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 789-9
Second edition
2018-02
Agricultural tractors — Test
procedures —
Part 9:
Power tests for drawbar
Tracteurs agricoles — Méthodes d'essai —
Partie 9: Essais de puissance à la barre d'attelage
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: [phone]
Fax: [phone]
Email: [e-mail]
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 . 1
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 Fuels and lubricants . 2
5.6.1 Selection . 2
5.6.2 Measuring consumption . . . 2
5.6.3 Tractors equipped with diesel particulate filters . 3
5.7 Auxiliary equipment . 3
5.8 Ambient conditions . 3
5.9 Tractor conditions . 3
5.9.1 Tyres . 3
5.9.2 Ballast . 3
5.10 Slip . 4
5.11 Testing rules . 4
5.12 Required measurements . 5
5.13 Warm-up. 5
6 Test procedure . 6
6.1 Maximum power. 6
6.1.1 General. 6
6.1.2 Geared transmissions . 6
6.1.3 Continuously variable transmissions . 6
6.2 Fuel consumption . 6
6.2.1 General. 6
6.2.2 Nominal speed of 7,5 km/h . 6
6.2.3 Nominal speed between 7 and 10 km/h . 7
6.2.4 Continuously variable transmissions . 7
6.2.5 Alternative tractor configuration . . 7
6.3 Tractors without PTO capable of transmitting full engine power . 7
6.3.1 General. 7
6.3.2 Varying drawbar pull and speed at full load . 8
6.3.3 Continuous one hour test at maximum power . 8
6.4 Statement of power rating . 8
7 Test report . 8
Annex A (normative) Drawbar tests — Measurement of tyre tread and track .10
Bibliography .11
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 second edition cancels and replaces the first edition (789-9:1990), which has been technically
revised for the technical harmonization with OECD Code 2: February 2017. It also incorporates the
Amendment ISO 789-9:1990/Amd.1:1993.
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 789-9:2018(E)
Agricultural tractors — Test procedures —
Part 9:
Power tests for drawbar
1 Scope
This document specifies test procedures for determining the power available at the drawbar on
agricultural tractors of the wheeled, track-laying or semi-track-laying type.
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 789-13:2018, Agricultural tractors — Test procedures — Part 13: Vocabulary and specimen test report
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 %;
— fuel consumption, in kilograms per kilowatt hour (kg/kWh): ± 1 %;
— atmospheric pressure, in kilopascals (kPa): ± 0,2 kPa;
— tyre pressure (gauge), in kilopascals (kPa): ± 5 %;
— temperature of fuels, etc., in degrees Celsius: ± 2 °C;
— wet and dry bulb thermometer temperature, in degrees Celsius: ± 0,5 °C.
5 General requirements
5.1 Selection
In the case of a third party performing the assessment, the tractor manufacturer and the third party
shall work together to select a tractor to be submitted for testing. The tractor submitted for the test
shall require a serial number, shall comply with the manufacturer’s product specification, and shall
be operated in accordance with the manufacturer’s instructions. The manufacturer shall provide a
representative to be present throughout the entire testing of the tractor.
5.2 Running-in and preliminary adjustments
5.2.1 The tractor shall be new and run-in prior to the test in accordance with the manufacturer’s
usual instructions. If a third party is responsible for the testing, the third party itself may run-in the
tractor provided an authority of the manufacturer or the manufacturer’s representative, who will remain
responsible for the running-in, is obtained.
The test report shall state the place and duration of running in.
5.2.2 The adjustment of the carburettor or injection pump as well as the setting of the governor shall
conform to the specifications provided by the manufacturer. The manufacturer may make adjustments in
conformity with these specifications prior to testing, but adjustments shall not be made during the test.
5.3 Manufacturer's instructions
Once the test has started, the tractor shall never be operated in a way that is not in accordance with
the manufacturer's published instructions in the form of an operating handbook unless specifically
required by test criteria and then only by arrangement with the manufacturer.
5.4 Repairs
All repairs made during the tests shall be noted in the test report, together with comments on any
practical defects or shortcomings about which there is no doubt.
5.5 Preliminary information
Specification information of the tractor consisting of the items listed in the ISO 789-13 specimen test
report, as well as any further data required to carry out the tests, shall be recorded and used to set up
the test.
These technical specifications shall be validated as thoroughly as possible by the entity performing
the test.
5.6 Fuels and lubricants
5.6.1 Selection
Fuels and lubricants shall be selected from the range of products commercially available in the country
where the equipment is tested, but shall conform to the minimum standards approved by the tractor
manufacturer. If the fuel or lubricant conforms to a national or international standard, it shall be
mentioned and the standard stated.
5.6.2 Measuring consumption
Measurement of fuel consumption during drawbar testing is required.
2 © ISO 2018 – All rights reserved

The fuel measurement apparatus shall be arranged so the fuel pressure at the carburettor or the fuel
injection pump is equivalent to that which exists when the tractor's fuel tank is hal
...

INTERNATIONAL ISO
STANDARD 789-9
Second edition
2018-02
Agricultural tractors — Test
procedures —
Part 9:
Power tests for drawbar
Tracteurs agricoles — Méthodes d'essai —
Partie 9: Essais de puissance à la barre d'attelage
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: [phone]
Fax: [phone]
Email: [e-mail]
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 . 1
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 Fuels and lubricants . 2
5.6.1 Selection . 2
5.6.2 Measuring consumption . . . 2
5.6.3 Tractors equipped with diesel particulate filters . 3
5.7 Auxiliary equipment . 3
5.8 Ambient conditions . 3
5.9 Tractor conditions . 3
5.9.1 Tyres . 3
5.9.2 Ballast . 3
5.10 Slip . 4
5.11 Testing rules . 4
5.12 Required measurements . 5
5.13 Warm-up. 5
6 Test procedure . 6
6.1 Maximum power. 6
6.1.1 General. 6
6.1.2 Geared transmissions . 6
6.1.3 Continuously variable transmissions . 6
6.2 Fuel consumption . 6
6.2.1 General. 6
6.2.2 Nominal speed of 7,5 km/h . 6
6.2.3 Nominal speed between 7 and 10 km/h . 7
6.2.4 Continuously variable transmissions . 7
6.2.5 Alternative tractor configuration . . 7
6.3 Tractors without PTO capable of transmitting full engine power . 7
6.3.1 General. 7
6.3.2 Varying drawbar pull and speed at full load . 8
6.3.3 Continuous one hour test at maximum power . 8
6.4 Statement of power rating . 8
7 Test report . 8
Annex A (normative) Drawbar tests — Measurement of tyre tread and track .10
Bibliography .11
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 second edition cancels and replaces the first edition (789-9:1990), which has been technically
revised for the technical harmonization with OECD Code 2: February 2017. It also incorporates the
Amendment ISO 789-9:1990/Amd.1:1993.
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 789-9:2018(E)
Agricultural tractors — Test procedures —
Part 9:
Power tests for drawbar
1 Scope
This document specifies test procedures for determining the power available at the drawbar on
agricultural tractors of the wheeled, track-laying or semi-track-laying type.
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 789-13:2018, Agricultural tractors — Test procedures — Part 13: Vocabulary and specimen test report
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 %;
— fuel consumption, in kilograms per kilowatt hour (kg/kWh): ± 1 %;
— atmospheric pressure, in kilopascals (kPa): ± 0,2 kPa;
— tyre pressure (gauge), in kilopascals (kPa): ± 5 %;
— temperature of fuels, etc., in degrees Celsius: ± 2 °C;
— wet and dry bulb thermometer temperature, in degrees Celsius: ± 0,5 °C.
5 General requirements
5.1 Selection
In the case of a third party performing the assessment, the tractor manufacturer and the third party
shall work together to select a tractor to be submitted for testing. The tractor submitted for the test
shall require a serial number, shall comply with the manufacturer’s product specification, and shall
be operated in accordance with the manufacturer’s instructions. The manufacturer shall provide a
representative to be present throughout the entire testing of the tractor.
5.2 Running-in and preliminary adjustments
5.2.1 The tractor shall be new and run-in prior to the test in accordance with the manufacturer’s
usual instructions. If a third party is responsible for the testing, the third party itself may run-in the
tractor provided an authority of the manufacturer or the manufacturer’s representative, who will remain
responsible for the running-in, is obtained.
The test report shall state the place and duration of running in.
5.2.2 The adjustment of the carburettor or injection pump as well as the setting of the governor shall
conform to the specifications provided by the manufacturer. The manufacturer may make adjustments in
conformity with these specifications prior to testing, but adjustments shall not be made during the test.
5.3 Manufacturer's instructions
Once the test has started, the tractor shall never be operated in a way that is not in accordance with
the manufacturer's published instructions in the form of an operating handbook unless specifically
required by test criteria and then only by arrangement with the manufacturer.
5.4 Repairs
All repairs made during the tests shall be noted in the test report, together with comments on any
practical defects or shortcomings about which there is no doubt.
5.5 Preliminary information
Specification information of the tractor consisting of the items listed in the ISO 789-13 specimen test
report, as well as any further data required to carry out the tests, shall be recorded and used to set up
the test.
These technical specifications shall be validated as thoroughly as possible by the entity performing
the test.
5.6 Fuels and lubricants
5.6.1 Selection
Fuels and lubricants shall be selected from the range of products commercially available in the country
where the equipment is tested, but shall conform to the minimum standards approved by the tractor
manufacturer. If the fuel or lubricant conforms to a national or international standard, it shall be
mentioned and the standard stated.
5.6.2 Measuring consumption
Measurement of fuel consumption during drawbar testing is required.
2 © ISO 2018 – All rights reserved

The fuel measurement apparatus shall be arranged so the fuel pressure at the carburettor or the fuel
injection pump is equivalent to that which exists when the tractor's fuel tank is half full. The fuel
temperature shall be comparable to that which is found during full load operation for 2 h, when the fuel
is taken from the tractor fuel tank.
5.6.3 Tractors equipped with diesel particulate filters
In the case of a tractor equipped with a diesel particulate filter, a regeneration of the diesel particulate
filter may be performed before starting the drawbar test. If the tractor initiates a regener
...