ISO 12161:2006

Road vehicles — Endurance braking systems of motor vehicles and towed vehicles — Test procedures

ISO 12161:2006 specifies methods for testing the endurance braking systems of vehicles of categories M, N and O (excluding M1, N1, O1 and O2), which are designed to comply with ECE-R 13/09 with supplements 1 to 6. All endurance test procedures are based on the principle of equivalent energy absorption. Procedures which are not suitable to support this principle are not considered. The principle of equivalent energy allows the base test parameters to be adapted to the variations occurring under real conditions compared to theoretical values.

Véhicules routiers — Véhicules à moteur et véhicules tractés disposant de systèmes de freinage d'endurance — Procédures d'essai

General Information

• Status: Published
• Publication Date: 27-Aug-2006
• ICS: 43.040.40 - Braking systems
• Technical Committee: ISO/TC 22/SC 33 - Vehicle dynamics and chassis components
• Drafting Committee: ISO/TC 22/SC 33 - Vehicle dynamics and chassis components
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 23-Sep-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 12161
First edition
2006-09-01

Road vehicles — Endurance braking
systems of motor vehicles and towed
vehicles — Test procedures
Véhicules routiers — Véhicules à moteur et véhicules tractés disposant
de systèmes de freinage d'endurance — Procédures d'essai




Reference number
ISO 12161:2006(E)
©
ISO 2006

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ISO 12161:2006(E)
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©  ISO 2006
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ISO 12161:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols and abbreviated terms . 5
5 General test conditions. 6
5.1 Ambient conditions . 6
5.2 Test site . 6
5.3 Vehicle preparation. 6
6 Downhill test. 7
6.1 General. 7
6.2 Downhill test track. 8
6.3 Normal test parameters. 8
6.4 Determination of specific test parameters. 9
6.5 Conducting the downhill test . 12
6.6 Presentation of results. 14
7 Drag test (gradient simulation test) . 14
7.1 General. 14
7.2 Drag test track. 14
7.3 Regular test parameters. 14
7.4 Determination of specific test parameters.15
7.5 Conducting the drag test . 15
7.6 Data processing and presentation of results . 16
8 Indoor vehicle test on a test bench (gradient simulation test) . 17
8.1 General. 17
8.2 Description of the test bench . 17
8.3 Normal test parameters. 18
8.4 Determination of specific test parameters.19
8.5 Conducting the dynamometer test . 19
8.6 Data processing and presentation of results . 20
Annex A (normative) Vehicle data .22
Annex B (normative) Test reports .23
Bibliography . 26

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ISO 12161:2006(E)
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 12161 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 2, Braking
systems and equipment.
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ISO 12161:2006(E)
Introduction
This International Standard applies to complete vehicles and not to endurance braking systems on their own.
Depending on the available test facilities the vehicles equipped with endurance braking systems shall be
tested for type approval using one of the following types of tests:
Outdoor tests
⎯ Downhill vehicle test (see Clause 6)
⎯ Vehicle drag test (see Clause 7)
Indoor test (see Clause 8)
⎯ Dynamometer vehicle test
All three tests are evaluated from downhill braking manoeuvres and are to different degrees gradient
simulation tests.

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INTERNATIONAL STANDARD ISO 12161:2006(E)

Road vehicles — Endurance braking systems of motor vehicles
and towed vehicles — Test procedures
IMPORTANT — When using this International Standard, care should be taken to ensure that changes
have not subsequently been adopted that affect the test methods or values given.
1 Scope
This International Standard specifies methods for testing the endurance braking systems of vehicles of
categories M N and O (excluding M1, N1, O1 and O2) which are designed to comply with ECE-R 13/09 with
supplement 1 to 6. The values given in square brackets are taken from ECE Regulation No. 13 for information.
All endurance test procedures are based on the principle of equivalent energy absorption and procedures
which are not suitable to support this principle are not considered.
The principle of equivalent energy allows the base test parameters to be adapted to the variations occurring
under real conditions compared to theoretical values.
NOTE Typical sources are:
⎯ The variation of the gradient of downhill test track or
⎯ The variation of retarding force during drag tests or indoor test.
2 Normative references
The following referenced documents are indispensable for the application 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 611: 2003, Road vehicles — Braking of automotive vehicles and their trailers — Vocabulary
ISO 1176: 1990, Road vehicles — Masses — Vocabulary and codes
ISO 3833: 1977, Road vehicles — Types — Terms and definitions
ISO 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary
ECE Regulation No. 13, Uniform provisions concerning the approval of vehicles with regard to braking,
incorporating the series 09 with supplements 1 to 6
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 611, ISO 1176 and ISO 3833 and
the following apply.
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ISO 12161:2006(E)
3.1
vehicle categories
as defined in ECE R.E.3, the Consolidated Resolution on the construction of vehicles:
⎯ category M: power-driven vehicles having at least four wheels and used for the carriage of passengers;
⎯ category N: power-driven vehicles having at least four wheels and used for the carriage of goods
3.2
endurance braking system
total of all devices of a vehicle which enable the driver to reduce the speed or to transverse a long descent at
nearly a constant speed without the use of the service brake
NOTE 1 An endurance braking system may contain one or more retarder(s), and may include:
⎯ energy supplying means;
⎯ control device(s);
⎯ transmission means;
⎯ retarder(s);
⎯ energy dissipation device(s);
⎯ auxiliary device(s).
NOTE 2 All retarders are new and fully burnished according to the supplier recommendations.
3.2.1
types of control device used in endurance braking system

3.2.1.1
independent control device
device which controls the endurance braking system independently from the service braking system
3.2.1.2
integrated control device
device applied simultaneously with the service braking systems or with a suitably phased operation
3.2.1.3
vehicle speed control device
device which allows a nearly constant vehicle speed by automatic operation and modulation of the endurance
braking system
3.2.1.4
cut-out device
device which allows to apply the service braking system alone or to use the vehicle speed control without
actuating the endurance braking system
NOTE This is a combined control device.
3.2.2
retarder
energy transformation device used to provide braking effort allowing control of vehicle speed independently of
or as a supplement to the friction brakes
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ISO 12161:2006(E)
3.2.2.1
categories of retarders

3.2.2.1.1
primary retarder
retarder located on the drive train of a motor vehicle at the engine side of the gearbox (torque converter)
3.2.2.1.2
secondary retarder
retarder located on the drive train of motor vehicles between the gearbox (torque converter) and the drive
axle(s)
NOTE Retarders can be connected to non-driven axles and are also classed as secondary retarders.
3.2.2.1.3
other retarders
retarders which are not categorized in 3.2.2.1.1 or 3.2.2.1.2 (e.g. aerodynamic retarders)
3.2.2.2
types of retarders
3.2.2.2.1
combustion engine retarder
3.2.2.2.1.1
engine braking
means whereby the engine drag resulting from the reduction of the fuel input and the throttling of the induction
air supply whilst the engine is linked to the driving wheels retards the vehicle (see 5.5.3.1.3.1 of
ISO 611:2003)
3.2.2.2.1.2
engine retarder
mechanism in which an increased retarding effect is obtained by changing the valve timing to increase the
internal resistance (drag) of the engine (see 5.5.3.1.3.2 of ISO 611:2003)
3.2.2.2.1.3
exhaust retarder
mechanism in which an increased retarding effect is obtained by blocking the flow of the exhaust gas to
increase the internal resistance of the engine (see 5.5.3.1.3.3 of ISO 611:2003)
3.2.2.2.2
electric traction motor retarder
mechanism in which the electric traction motor, linked to the driving wheels, exercises a retarding effect on the
moving vehicle, for example, by functioning as a current generator (see 5.5.3.1.3.4 of ISO 611:2003)
3.2.2.2.3
hydraulic retarder
retarder in which a retarding effect is obtained by the action of liquid on rotating/pumping components linked
to one or more wheels
3.2.2.2.3.1
hydrodynamic retarder
hydraulic retarder in which the power absorption is based on the principle of specific kinetic energy of a fluid
3.2.2.2.3.2
hydrostatic retarder
hydraulic retarder in which the power absorption is based on the principle of specific kinetic energy of a fluid
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ISO 12161:2006(E)
3.2.2.2.4
electric retarders

3.2.2.2.4.1
electromagnetic retarder
retarder in which a retarding effect is obtained by the action of an electromagnetic field on a rotating
component (eddy current, hysteresis) linked to one or more wheels
3.2.2.2.4.2
permanent-magnetic retarder
mechanism in which a retarding effect is obtained by the action of a permanent-magnetic field on a rotating
component (eddy current, hysteresis) linked to one or more wheels
3.2.2.2.5
regenerative braking retarder
any type of retarder which recovers the vehicle’s kinetic energy through the braking torque in order to restore
it to a vehicle energy reservoir
3.2.2.2.6
aerodynamic retarder
mechanism in which a retarding effect is obtained by causing an increase in the air resistance, for example, by
the deployment of movable surfaces
[ISO 611:2003]
3.3
vehicle loading

3.3.1
laden vehicle
vehicle laden to its maximum technically permissible mass as specified by the vehicle manufacturer and
acknowledged by the technical services
3.4
energy

3.4.1
dissipated energy
amount of energy dissipated through braking during any braking operation of a vehicle or vehicle combination
taking into account a rolling resistance of 1 % of g
WW=−W
diss pot rr
Wm=×g× ∆H
pot
⎛⎞∆H
Wm=×g× × 0,01
rr ⎜⎟
tanα
⎝⎠
3.4.2
equivalent energy W
equ,II
energy of a vehicle dissipated while braking downhill when this dissipated energy is equivalent to that
dissipated in the same period of time with the vehicle driven at an average speed of 30 km/h on a [6 %]
down-gradient for a distance of [6 km]
WW==f tanα= 6 %,l= 6km
( )
equ,II diss,II
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ISO 12161:2006(E)
4 Symbols and abbreviated terms
For the purposes of this International Standard, the symbols given in Table 1 apply.
Table 1 — Symbols
α angle of the down gradient (from the horizontal) rad
2
a mean deceleration m/s
m
2
d mean fully developed deceleration m/s
m
E wheelbase m
F towing force N
F rolling resistance N

rr
l length of the test “track” or equivalent m, km
ll′′, ′ modified length of the test “track” or equivalent m, km
m mass of the vehicle or vehicle combination kg
M torque, braking torque, driving torque of dynamometer Nm
′′′
mm, modified mass kg
N number of measurement samples -
P power W
P retarding power resp. braking power W

ret
P dissipated power due to the rolling resistance while braking Nm/s or W
rr
r radius m
t time s
T duration of the test s
T required duration of the test s

req
tan α gradient of the down slope %
tan α average gradient of the downhill test road %

m
′
tan α modified average gradient of the downhill test road %
m
v vehicle speed m/s
v average speed m/s

aver
v required test speed m/s

req
′′′
vv, modified vehicle speed m/s
W dissipated energy while braking Nm or W

diss
W potential energy while downhill braking Nm or W
pot
W dissipated energy due to the rolling resistance while braking Nm or W
rr
∆H difference of altitude m

′′′
∆∆H , H modified difference of altitude m

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ISO 12161:2006(E)
5 General test conditions
5.1 Ambient conditions
5.1.1 Wind speed
The tests shall be performed when there is no wind liable to affect the results.
5.1.2 Air temperature
The air temperature shall be noted in the test report.
5.1.3 Road surface condition
Any test road shall be smooth, hard-surfaced and free of loose material, and thereby provide a sufficient peak
coefficient of adhesion to prevent excessive wheel slip.
5.2 Test site
Any test site should be of adequate size and length and without obstacles, and be able to provide a safe
testing environment.
The length of the test track shall be established by suitable means of distance measurements with a tolerance
of ± 1,0 %.
5.3 Vehicle preparation
5.3.1 Instrumentation
The test vehicle (and the towing vehicle if appropriate) shall be prepared for testing by the installation of
additional instruments and/or calibration of the existing standard vehicle instruments, as required.
All the instruments shall be checked to ensure correct function and, with the vehicle stationary on the test
surface, all the instruments shall be set.
The instrumentation shall be able to measure the following parameters.
5.3.1.1 Vehicle speed
If the recording of the vehicle speed is required, a separate speed measuring device independent of any
wheel slip shall be used.
5.3.1.2 Duration of the test
The duration of the test shall be measured by means of a chronometer or electronic timing equipment.
5.3.1.3 Engine speed
For monitoring the permissible engine speed, the instrument on the dashboard is sufficient.
5.3.1.4 Temperatures
For surveying the permissible temperature of the engine cooling system the instrument on the dashboard is
sufficient.
Separate temperature measuring means shall be used when stabilized operating conditions are required.
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ISO 12161:2006(E)
5.3.1.5 Towing force
The towing force during the drag test shall be measured by means of a strain-gauged and calibrated towing
link/coupling, and the measuring system shall provide a visible reading and a signal for producing a
permanent force record.
5.3.2 Verification and calibration of the measuring instruments
Prior to the test check that:
⎯ the vehicle instruments such as the tachograph, the engine revolution-counter and the coolant
thermometer work properly;
⎯ a separate distance and speed measuring system and the chronometer work properly;
⎯ other sensors such as the towing link sensor system are calibrated and registered.
5.3.3 Vehicle to be tested
5.3.3.1 Vehicle
Technical data of the test vehicle or vehicle combination shall be recorded according to Annex A.
At the beginning of the test, the normal operating temperature of the engine according to the operator’s
manual shall be reached.
5.3.3.2 Endurance braking system
For evaluation of the test results, the technical specification of the endurance braking system shall be
recorded according to Annex A.
The endurance braking system shall be in proper working condition and ready for operation. This includes
making sure that the normal operating temperatures according to the manufacturer’s specifications are
reached.
The instructions of the endurance braking system manufacturer (see operating instructions of endurance
braking system) shall be taken into account.
5.3.3.3 Towing vehicle
The towing vehicle shall be able to pull the test vehicle or vehicle combination during the whole test with a
nearly constant speed as required. Gear changing shall be limited to a necessary minimum. It shall be
possible to communicate with the driver of the test vehicle by either visual or audible means.
6 Downhill test
6.1 General
The basic requirement of the downhill test is that the dissipated energy shall be equal to the equivalent energy
according to ECE-R 13 Annex 4.
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ISO 12161:2006(E)
6.2 Downhill test track
6.2.1 General
The downhill test may be made on any quiet road where the average gradient and length satisfy the required
values (e.g. 6 % and 6 km according to UN-ECE Regulation 13 or variations thereof according to 6.4).
However, the local gradient is not required to be strictly constant but may vary along the test road.
6.2.2 Altitude difference
The difference in altitude between two points along the test track shall be determined by suitable means of
altitude measurements with a tolerance of ± 0,5 %.
6.2.3 Gradient of test road
The average gradient of the downhill test road is the difference of the altitudes between the beginning and the
end of the test track divided by the distance between those points.
H
tanα =
m
l
6.2.4 Permissible tolerance of local gradient along the test track
The local gradient tan α along the test road may vary ± 50 % of tan α .
loc m
6.2.5 Specific local characteristics of a realistic downhill test road
A downhill road including a maximum of five curves or temporary obstacles, requiring a short and significant
speed reduction but not below 10 km/h, is allowed as a test site. These conditions permit correction as stated
in 6.4 to be valid.
6.3 Normal test parameters
The following regular test parameters are:
⎯ length of the test road;
⎯ gradient of the test road;
⎯ test speed; and
⎯ loading condition — laden.
The parameters given in Table 2 shall be taken from the values given by Regulation 13 and shall be used as a
basis for the test.
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ISO 12161:2006(E)
Table 2 — Regular test parameters given by Regulation 13
ECE-R 13 Speed Distance Rolling resistance
Gradient (tanα )
Annex 4 km/h % km %
Type II 30 6 6 1
Type IIA 30 7 6 1

The normal duration of the test is 12 min, calculated from speed and distance.
The difference of altitude of the downhill test road may be calculated using the values of Table 2 and the
following formula:
∆αHl= tan
The mass of the vehicle or the vehicle combination to be tested shall be specified by the applicant according
to the required loading condition.
6.4 Determination of specific test parameters
6.4.1 General
The test parameters, such as speed, gradient, mass, etc., shall be determined according to the real conditions
of the available test track in order to conduct the tests alternatively on downhill test sites with gradients which
differ from those of Table 2. Based on the principle of equivalent energy, the specific parameters or
combinations of parameters may be altered as set out in the following clauses. The calculations and results
thereof shall be documented.
6.4.2 Required adjustment of altitude and duration of the type IIA test to compensate for a short
application of the service braking system
For a test road with a number of narrow curves or temporary obstacles which require an additional but brief
short use of the service braking system as specified in 6.2.5, the test parameters shall be compensated as
follows:
⎯ For each significant speed reduction by using the service braking system the length of the test track shall
be extended in advance such that the difference in altitude shall be increased by 7 m. The required
duration of the test and the distances travelled shall be extended according to 6.5.2.2.2 or 6.5.2.2.3.
⎯ As an alternative to the extension of the length of the test road, the mass of the vehicle or vehicle
combination may be increased in order to add the corresponding amount of energy (see 6.4.3).
6.4.3 Adjustment of mass to compensate for a difference of altitude
If the available test road provides the prescribed length but not the prescribed gradient and thus a difference
of altitude ∆H' different from the necessary altitude difference (see Figure 1), the mass of the test vehicle or
vehicle combination shall be modified to m´ using the following formula, which is based on the principle of the
equivalent energy:
∆H−×0,01 l
mm′=×
∆H ′−×0,01 l
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ISO 12161:2006(E)

Key
1 top
2 bottom
3 W = const.
diss
4 I = const.
5 ∆H variable
Figure 1 — Variable altitude
6.4.4 Adjustment of test speed to compensate for a deviation of gradient
If the available test road provides the prescribed altitude difference but not the prescribed gradient and thus
the road length (see Figure 2), the average test speed v' shall be calculated from the average gradient of the
actual downhill test road tanα´ (based on the principle of the equivalent energy and the nominal mass of the
vehicle or combination), and is such that the duration of the test shall not be altered:
tanα − 0,01
′
vv=×
′
tanα − 0,01
Due to the fact that the same period of time is required, the necessary length of the downhill test track shall
be:
v′
′
ll=×
v
The resulting difference of altitude is:
∆αHl′′= tan′
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ISO 12161:2006(E)

Key
1 top
2 bottom
3 m = const., p = const.
4 variable tanα
5 variable l
Figure 2 — Variable gradient
Table 3 — Examples for type II
Variable Unit Normal value Example 1 Example 2 Example 3 Example 4
% 6,0 5,5 5,2 6,5 7,2
tan α
v km/h 30,0 33,3 35,7 27,3 24,2
l km 6,0 6,7 7,1 5,5 4,8
m 360,0 366,7 371,4 354,5 348,4
∆ H

Table 4 — Examples for type IIA
Variable Unit Normal value Example 1 Example 2 Example 3 Example 4
tan α % 7,0 6,5 6,0 7,5 8,5
v
km/h 30,0 32,7 36,0 27,7 24,0
l km 6,0 6,5 7,2 5,5 4,8
m 420,0 425,5 432,0 415,4 408,0
∆ H

The calculated average test speed v shall match the normal parameter test speed [30 km/h] within a
calc
tolerance of ± 20 %.
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ISO 12161:2006(E)
If the calculated average test speed v exceeds this tolerance range, this road is not suitable for downhill
calc
testing of vehicles with nominal mass. However, modification of the mass of the vehicle or combination of
vehicles may be determined according to 6.4.5.
6.4.5 Adjustment of vehicle mass and speed to compensate for a deviation of road gradient
and length
If the available test road provides the required altitude difference but not the required gradient and thus road
length such that the calculated average test speed according to 6.4.4 exceeds the tolerance of ± 20 %, the
mass of the vehicle or combination of vehicles may be modified so as to correct the dissipated energy.
The mass shall be calculated from the average gradient so that the resulting speed is within the tolerance
range.
tanα − 0,01
′
vv=×
′
tanα − 0,01
v' is the calculated speed v , which is out of tolerance v'' shall now be chosen within the tolerance
calc
30 km/h ± 20 %.
v′
′′ ′ ′
mm=× ()m=m
′′
v
The nominal duration of the test shall not be altered. Therefore, the length of the test track is required as
following:
v"
ll"'=×
v'

The resulting difference of altitude is:
∆αHl′′=×′′ tan ′
When the calculated difference of altitude can not be provided, this road is not sui
...