ISO 789-9:2018

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
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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
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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
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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,
...