SIST ISO 789-3:2016

Agricultural tractors - Test procedures - Part 3: Turning and clearance diameters

ISO 789-3:2015 specifies a method of determining the turning and clearance diameters of wheeled agricultural tractors.
It applies to wheeled agricultural tractors having at least two axles fitted with pneumatic tyres.

Tracteurs agricoles - Méthodes d'essai - Partie 3: Diamètres de braquage et de dégagement

Kmetijski traktorji - Preskusne metode - 3. del: Premer obračalnega kroga in kroga, ki ga opiše skrajna zunanja točka traktorja

Ta del standarda ISO 789 določa metodo za ugotavljanje premera obračalnega kroga in kroga, ki ga opiše skrajna zunanja točka
kmetijskega traktorja s kolesi. Uporablja se za kolesne traktorje, ki se uporabljajo v kmetijstvu, z najmanj dvema osema za kolesa s pnevmatikami.

General Information

• Status: Published
• Publication Date: 28-Mar-2016
• ICS: 65.060.10 - Agricultural tractors and trailed vehicles
• Technical Committee: IMKG - Machinery for agriculture and forestry
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 21-Mar-2016
• Due Date: 26-May-2016
• Completion Date: 29-Mar-2016
• Ref Project: ISO 789-3:2015 - Agricultural tractors - Test procedures - Part 3: Turning and clearance diameters

Relations

• Replaces: SIST ISO 789-3:1997 - Agricultural tractors -- Test procedures -- Part 3: Turning and clearance diameters
• Effective Date: 01-May-2016

Overview

ISO 789-3:2015 - "Agricultural tractors - Test procedures - Part 3: Turning and clearance diameters" specifies a standardized method for measuring the turning diameter and clearance diameter of wheeled agricultural tractors fitted with pneumatic tyres. The standard defines terms (track, wheelbase, turning and clearance diameters), required apparatus, test-area and tractor setup requirements, measurement procedures (direct and GPS-based) and reporting requirements.

Key topics and requirements

• Scope: Applies to wheeled agricultural tractors with at least two axles and pneumatic tyres.
• Definitions: Precise definitions of turning diameter (path of tyre contact centre) and clearance diameter (smallest circle enclosing outermost tractor projections) are provided.
• Apparatus:
  • Tape measure (length > expected diameter) with tolerance ±0.5%
  • Plumb-line (for clearance point marking)
  • Corrected GPS equipment (alternate method) with linear accuracy sufficient for ±0.5% tolerance
• Test area: Compacted or paved, dry surface with good tyre adhesion and legible markings; visually flat with no more than 3% grade. For GPS tests, avoid obstructions that affect satellite reception.
• Tractor setup:
  • Use tire, wheel and fender equipment as commonly used for intended market; record tyre pressures, ballast and dual-wheel use.
  • Standard track (tread) setting: 1 500 mm ± 25 mm (or nearest manufacturer-specified setting).
  • Test each operating condition for vehicles with steerable axles, disconnectable axles or selectable drive modes; record results for each condition.
• Procedure:
  • Perform sharpest practicable right- and left-hand turns at steering full lock, speed not exceeding 2 km/h.
  • Direct method: mark outer tyre contact points around at least one complete turn, use plumb-line to mark outermost projection, measure diameters at three equally spaced positions and average.
  • GPS method: record antenna track and coordinates, calculate turning and clearance diameters per the ISO geometry.
  • Brake-assisted test (where applicable): apply inside non-steered wheel brake to lock (pedal effort up to 60 daN) and repeat tests.
• Reporting: Test report and specimen form (Annex A) specify required recorded data and measured values.

Applications and users

ISO 789-3:2015 is used by:

• Tractor manufacturers and design engineers for validating steering geometry and packaging
• Test laboratories and certification bodies for performance verification and compliance
• R&D teams and dealerships evaluating manoeuvrability, clearance requirements and field suitability
• Fleet managers and agricultural equipment specifiers comparing tractors for confined-field and transport operations

Keywords: ISO 789-3:2015, agricultural tractors, turning diameter, clearance diameter, tractor test procedures, GPS measurement, track setting, wheelbase, tyre pressure.

Related standards

Part of the ISO 789 series (tractor test procedures). Related parts include ISO 789-1 (PTO power tests), ISO 789-2 (rear three-point linkage), ISO 789-11 (steering capability) and others in the ISO 789 family.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2016
1DGRPHãþD
SIST ISO 789-3:1997
.PHWLMVNLWUDNWRUML3UHVNXVQHPHWRGHGHO3UHPHUREUDþDOQHJDNURJDLQNURJD
NLJDRSLãHVNUDMQD]XQDQMDWRþNDWUDNWRUMD
Agricultural tractors - Test procedures - Part 3: Turning and clearance diameters
Tracteurs agricoles - Méthodes d'essai - Partie 3: Diamètres de braquage et de
dégagement
Ta slovenski standard je istoveten z: ISO 789-3:2015
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 789-3
Third edition
2015-09-01
Agricultural tractors — Test
procedures —
Part 3:
Turning and clearance diameters
Tracteurs agricoles — Méthodes d’essai —
Partie 3: Diamètres de braquage et de dégagement
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Terms and definitions . 1
3 Apparatus . 5
4 General requirements . 5
4.1 Test area . 5
4.2 Tractor test requirements . 5
4.2.1 Tire and wheel equipment . 5
4.2.2 Track (tread) setting . 5
4.2.3 Other settings . 5
5 Procedure. 6
5.1 Right-hand turn, without brakes . 6
5.1.1 Direct measurement . 6
5.1.2 Alternate GPS method . 6
5.2 Left-hand turn, without brakes . 6
5.3 Right-hand turn, with brakes . 7
5.4 Left-hand turn, with brakes . 7
6 Test report .10
Annex A (informative) Specimen test report .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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 23, Tractors and machinery for agriculture and
forestry, Subcommittee 2, Common tests.
This third edition cancels and replaces the second edition (ISO 789-3:1993), which has been
technically revised.
ISO 789 consists of the following parts, under the general title Agricultural tractors — Test procedures:
— Part 1: Power tests for power take-off
— Part 2: Rear three-point linkage lifting capacity
— Part 3: Turning and clearance diameters
— Part 4: Measurement of exhaust smoke
— Part 5: Partial power PT0 – Non-mechanically transmitted power
— Part 6: Centre of gravity
— Part 7: Axle power determination
— Part 8: Engine air cleaner
— Part 9: Power tests for drawbar
— Part 11: Steering capability of wheeled tractors
— Part 12: Low temperature starting
ISO/OECD 789 consists of the following parts, under the general title Agricultural tractors – Test procedures:
— Part 10: Hydraulic power at tractor/implement interface
iv © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 789-3:2015(E)
Agricultural tractors — Test procedures —
Part 3:
Turning and clearance diameters
1 Scope
This part of ISO 789 specifies a method of determining the turning and clearance diameters of wheeled
agricultural tractors.
It applies to wheeled agricultural tractors having at least two axles fitted with pneumatic tyres.
2 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
2.1
agricultural tractor
self-propelled agricultural vehicle having at least two axles and wheels, or endless tracks, particularly
designed to pull agricultural trailers and to pull, push, carry and operate implements used for
agricultural work (including forestry work), which may be provided with detachable loading platform
Note 1 to entry: The agricultural vehicle has a maximum design speed of not less than 6 km/h and may be
equipped with one or more seats.
[SOURCE: ISO 12934:2013, 3.1]
2.2
track
tread
distance at ground level between two vertical planes passing through the centreline
of ground contact of the tires parallel to the median plane of the tractor with the wheels in the straight
ahead position
Note 1 to entry: In the case of dual wheels, it is the distance at ground level between two planes passing through
the centreline of the dual wheels.
Note 2 to entry: See Figure 1.
Figure 1 — Track (tread) of the wheeled tractor
2.3
wheelbase
horizontal distance between the two vertical planes passing through the rotational centrelines of the
wheels, where one plane is for the front wheels and the other for the rear wheels
Note 1 to entry: In the case of a tractor equipped with a rear tandem, it is the distance between two vertical
planes passing through the centres of the front wheel and the vertical plane midway between the wheel centres
of the two axles of the tandem.
Note 2 to entry: See Figure 2.
2 © ISO 2015 – All rights reserved

Figure 2 — Wheelbase of the wheeled tractor
2.4
turning diameter
diameter of the circular path described by the centre of tire contact with the surface of the test site of
the wheel describing the largest circle when the tractor is executing its sharpest practicable turn under
the test conditions described in Clause 5
Note 1 to entry: See Figure 3.
2.5
clearance diameter
diameter of the smallest circle which will enclose the outermost points of projection of the
...

INTERNATIONAL ISO
STANDARD 789-3
Third edition
2015-09-01
Agricultural tractors — Test
procedures —
Part 3:
Turning and clearance diameters
Tracteurs agricoles — Méthodes d’essai —
Partie 3: Diamètres de braquage et de dégagement
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Terms and definitions . 1
3 Apparatus . 5
4 General requirements . 5
4.1 Test area . 5
4.2 Tractor test requirements . 5
4.2.1 Tire and wheel equipment . 5
4.2.2 Track (tread) setting . 5
4.2.3 Other settings . 5
5 Procedure. 6
5.1 Right-hand turn, without brakes . 6
5.1.1 Direct measurement . 6
5.1.2 Alternate GPS method . 6
5.2 Left-hand turn, without brakes . 6
5.3 Right-hand turn, with brakes . 7
5.4 Left-hand turn, with brakes . 7
6 Test report .10
Annex A (informative) Specimen test report .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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 23, Tractors and machinery for agriculture and
forestry, Subcommittee 2, Common tests.
This third edition cancels and replaces the second edition (ISO 789-3:1993), which has been
technically revised.
ISO 789 consists of the following parts, under the general title Agricultural tractors — Test procedures:
— Part 1: Power tests for power take-off
— Part 2: Rear three-point linkage lifting capacity
— Part 3: Turning and clearance diameters
— Part 4: Measurement of exhaust smoke
— Part 5: Partial power PT0 – Non-mechanically transmitted power
— Part 6: Centre of gravity
— Part 7: Axle power determination
— Part 8: Engine air cleaner
— Part 9: Power tests for drawbar
— Part 11: Steering capability of wheeled tractors
— Part 12: Low temperature starting
ISO/OECD 789 consists of the following parts, under the general title Agricultural tractors – Test procedures:
— Part 10: Hydraulic power at tractor/implement interface
iv © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 789-3:2015(E)
Agricultural tractors — Test procedures —
Part 3:
Turning and clearance diameters
1 Scope
This part of ISO 789 specifies a method of determining the turning and clearance diameters of wheeled
agricultural tractors.
It applies to wheeled agricultural tractors having at least two axles fitted with pneumatic tyres.
2 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
2.1
agricultural tractor
self-propelled agricultural vehicle having at least two axles and wheels, or endless tracks, particularly
designed to pull agricultural trailers and to pull, push, carry and operate implements used for
agricultural work (including forestry work), which may be provided with detachable loading platform
Note 1 to entry: The agricultural vehicle has a maximum design speed of not less than 6 km/h and may be
equipped with one or more seats.
[SOURCE: ISO 12934:2013, 3.1]
2.2
track
tread
distance at ground level between two vertical planes passing through the centreline
of ground contact of the tires parallel to the median plane of the tractor with the wheels in the straight
ahead position
Note 1 to entry: In the case of dual wheels, it is the distance at ground level between two planes passing through
the centreline of the dual wheels.
Note 2 to entry: See Figure 1.
Figure 1 — Track (tread) of the wheeled tractor
2.3
wheelbase
horizontal distance between the two vertical planes passing through the rotational centrelines of the
wheels, where one plane is for the front wheels and the other for the rear wheels
Note 1 to entry: In the case of a tractor equipped with a rear tandem, it is the distance between two vertical
planes passing through the centres of the front wheel and the vertical plane midway between the wheel centres
of the two axles of the tandem.
Note 2 to entry: See Figure 2.
2 © ISO 2015 – All rights reserved

Figure 2 — Wheelbase of the wheeled tractor
2.4
turning diameter
diameter of the circular path described by the centre of tire contact with the surface of the test site of
the wheel describing the largest circle when the tractor is executing its sharpest practicable turn under
the test conditions described in Clause 5
Note 1 to entry: See Figure 3.
2.5
clearance diameter
diameter of the smallest circle which will enclose the outermost points of projection of the tractor and
its equipment while executing its sharpest practicable turn
Note 1 to entry: See Figure 3.
Figure 3 — Tractor turning configurations
4 © ISO 2015 – All rights reserved

3 Apparatus
3.1 Tape measure, of length greater than the turning and clearan
...