ISO 26867:2009

DRAFT INTERNATIONAL STANDARD ISO/DIS 26867
ISO/TC 22/SC 2 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2008-02-22 2008-07-22
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Road vehicles — Brake lining friction materials — Friction
behaviour assessment for automative brake systems
Véhicules routiers — Matériaux de friction pour garnitures de freins — Évaluation du comportement en friction
pour les systèmes de freinage automatiques
ICS 43.040.40
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©
International Organization for Standardization, 2008

ISO/DIS 26867
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ii ISO 2008 – All rights reserved

ISO/DIS 26867
Contents Page
1 Scope and field of application .1
2 Normative references.1
3 Symbols and abbreviated terms .1
4 Terms and definitions .2
5 Test conditions and preparation.5
5.1 Inertia for the front axle .5
5.2 Inertia for the rear axle.5
5.3 Test wheel load.5
5.4 Pressure ramp rate.6
5.5 Maximum pressure.6
5.6 Pressure level with no power assist.6
5.7 Sampling rate.6
5.8 Initial brake temperature.6
5.9 Brake warm-up.6
5.10 Temperature measurement .6
5.11 Brake fluid displacement measurement .6
5.12 Cooling air conditions.6
5.13 Cooling air velocity or volume .7
5.14 Conditioning settings for temperature and absolute humidity (humidity ratio).7
5.15 Dynamometer rotational speed between brake applications .7
5.16 Orientation of brake setup.7
5.17 Direction of air with regard to brake setup.7
5.18 Brake cooling rate .7
5.19 Wear measurement .7
5.20 Lateral run-out .7
5.21 Rotor or drum conditions .7
5.22 Fade sections.8
5.23 Data collection.9
6 Test procedures.9
6.1 Test procedure for product monitoring with no optional brake applications.9
6.2 Test procedure for product development with additional brake applications.10
7 Test report.12
7.1 Graphical report.12
7.2 Tabular data for each brake application .12
7.3 Wear measurements .13
7.4 Test conditions .13
7.5 Cooling air conditions.13
7.6 Brake cooling rate .13
7.7 Friction values .13
7.8 Statistical analysis .13
Annex A (informative) Vehicle and test parameters (per clause 5) .14
Annex B (informative) Sample report for disc brakes.15
B.1 graphical summaries.15
B.1.1 constant deceleration or pressure sections, graph instantaneous values versus stop or snub
number.15
B.1.2 Burnish section, graph snubs 2, 15, and 30. .15
B.1.3 Average by distance friction marker, include a marker for the average by distance friction for
all the stops or snubs graphed. .15
ISO/DIS 26867
Annex C (informative) Histograms for instantaneous friction values (per clauses 7.1.3 and 7.1.4) . 17
Annex D (informative) Reference calculations for cooling air speed and flow (per clause 5.13) . 19
D.1 Conversion between airflow and cooling air speed. 19
D.2 Calculation of cooling air speed passing over the brake. 20

iv © ISO 2008 – All rights reserved

ISO/DIS 26867
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 26867 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 2, Brake
systems and equipment.
ISO/DIS 26867
Introduction
The efforts of harmonization among different countries and technical groups have the modernization of friction
behaviour characterization of automotive brake systems applications as a top priority. This International
Standard is intended to replace previous friction evaluation testing based solely on drag brake applications,
which do not take into account real-life driving conditions, or vehicle specific parameters.
The varied condition under which the friction material is evaluated ensures a wide spectrum of data that is
critical during the various phases of product life such as product and manufacturing process development,
production validation, quality control, product auditing and field issues evaluation.
Use this International Standard in conjunction with other applicable standards or test procedures (ISO, SAE,
JASO, Federal Codes or regulations, and other project or company-specific testing programs) to fully assess a
friction material’s adequacy for use in a certain application, market or vehicle platform. This International
Standard does not include performance requirements related to stopping distance or braking force distribution,
under different vehicle conditions of speed, temperature, tire-to-road adhesion, loads, and operating
conditions of the braking system as indicated on Federal Codes or Regulations.
This International Standard is intended as a friction evaluation inertia-dynamometer test procedure to replace
previous test protocols that depend solely upon drag applications. This Standard supports the friction
assessment during the life cycle of a friction material.
Friction evaluation and characterization by performing drag applications, which were once a valid replacement
for sample and scale testing, have now proven a limited approach. Drag applications do not correlate with
real-world driving conditions, brake system characteristics, or vehicle dynamics. Lining transfer layer
properties,
...