ISO 7634:2007

INTERNATIONAL ISO
STANDARD 7634
Third edition
2007-06-01
Road vehicles — Compressed air braking
systems for towed vehicles including
those with electronic braking control
functions — Test procedures
Véhicules routiers — Dispositifs de freinage à air comprimé pour
véhicules remorqués, y compris ceux avec fonctions de commande de
freinage électroniques — Modes opératoires d'essai

Reference number
©
ISO 2007
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©  ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols . 3
5 Test site conditions . 7
5.1 Test site . 7
5.2 Road surface condition. 7
5.3 Ambient conditions . 8
6 General requirements. 8
7 Recommended sequence of tests. 9
7.1 Preparation and static checks and tests. 9
7.2 Basic performance tests – unladen . 10
7.3 Antilock braking system/electronically controlled braking system (ABS/EBS) tests —
unladen . 10
7.4 Basic performance tests — Laden. 10
8 Vehicle preparation. 11
8.1 Documents and basic data . 11
8.2 Braking system condition and bedding . 11
8.3 Adjustment of braking equipment . 11
8.4 Tyre conditions . 12
8.5 Towing vehicles . 12
8.6 Instrumentation — General. 12
8.7 Provision for failure simulation. 12
8.8 Loading condition. 13
8.9 Additional vehicle to tow the combination of normal towing vehicle and test trailer . 13
8.10 Additional instrumentation for ABS equipped trailers . 13
8.11 Additional instrumentation for trailer with an electric control line . 13
9 Energy storage capacity test. 14
9.1 Test conditions . 14
9.2 Test procedure . 14
9.3 Test requirement. 14
9.4 Presentation of results. 14
10 Service braking system — Response time measurement. 14
10.1 General. 14
10.2 Towing vehicle simulator. 15
10.3 Test conditions . 15
10.4 Test procedure . 15
10.5 Presentation of results. 16
11 Automatic braking . 16
12 Brake defect and failure warning signals. 16
12.1 Antilock braking system warning signal.16
12.2 EBS warning signal check . 16
13 Tests on trailers equipped with spring brake actuators. 16
13.1 Initial conditions . 16
13.2 Energy depletion test . 17
13.3 Spring brake actuation test. 17
13.4 Auxiliary release system check. 17
14 Dynamometer tests (alternative to vehicle tests) . 17
14.1 General . 17
14.2 Alternative type I tests (fade test for trailers of categories O and O ). 17
2 3
14.3 Alternative type III tests (fade test for category O trailers). 19
15 Transfer of results of type I or type III tests to other vehicles . 21
15.1 General . 21
15.2 Presentation of results . 22
16 Control failure of load-sensing device/function — Stationary test. 23
17 Auxiliary equipment failure. 24
18 Basic performance tests — Unladen . 24
18.1 Type O test (Service braking system cold brake effectiveness). 24
19 Antilock braking system/electronically controlled braking system (ABS/EBS) tests —
Unladen . 26
19.1 Determination of adhesion utilization on high adhesion surface. 26
19.2 Determination of the peak coefficient of adhesion on the high adhesion surface . 27
19.3 Wheel behaviour . 30
19.4 Split adhesion tests . 30
19.5 Energy consumption of the antilock braking system (on a high adhesion surface). 31
19.6 Antilock braking system failure. 33
19.7 Additional tests on trailers equipped with EBS. 33
20 Basic performance tests — Laden . 34
20.1 Parking braking system tests . 34
20.2 Type O test (Service braking system cold brake effectiveness). 37
20.3 Control failure of load-sensing device/function — Road test . 37
20.4 Type I test (fade test for trailers of categories O and O ). 37
2 3
20.5 Type III test (fade test for vehicles of category O ). 40
Annex A (normative) Description of test vehicle, axle or brake . 44
Annex B (normative) Test report. 47
Annex C (informative) Figures. 50
Bibliography . 54

iv © ISO 2007 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 7634 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 2, Braking
systems and equipment.
This third edition cancels and replaces the second edition (ISO 7634:2003), which has been technically
revised.
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