ISO 5101

2025-01
ISO/DISFDIS 5101:2024(en)
ISO/TC 22/SC 33
Secretariat: DIN
Date: 2025-09
Road vehicles — Field load specification for brake actuation and
modulation systems
Véhicules routiers — Spécification de la charge pour les systèmes d'actionnement et de modulation des freins
FDIS stage
ISO/DISFDIS 5101:20242025(en)
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Published in Switzerland
ii
ISO/DISFDIS 5101:20242025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General. 5
5 Percentiles of field coverage . 6
6 Base assumptions and boundary conditions . 9
6.1 General. 9
6.2 Lifetime specifications . 9
6.3 Number of brake operations. 12
6.4 Temperature distributions . 15
6.5 Brake pedal application profile . 22
7 Braking system usage . 26
7.1 Base brake function (BBF) . 26
7.2 Base brake function for vehicles with regenerative braking (BBF with recuperation) . 26
7.3 Dynamic stability functions . 41
7.4 Brake torque optimizing functions . 57
7.5 Assistance functions . 82
8 Substitution methods . 103
8.1 Dependent functions . 103
Bibliography . 108

iii
ISO/DISFDIS 5101:20242025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 33, Vehicle
dynamics, chassis components and driving automation systems testing.
This first edition cancels and replaces the first edition of ISO/PAS 5101:2021, which has been technically
revised.
The main changes are as follows:
— — introduction of methodology to structure and calculate the contribution of regenerative braking;
— — addition of temperature distributions for electric vehicles;
— — extension of base assumptions by further parameters.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO/DISFDIS 5101:20242025(en)
Introduction
Vehicle development programs tend to grow in complexity and integration of the braking system with chassis
dynamics and mechatronics, demanding more robust and comprehensive evaluation programs. Also, to
remain competitive, braking systems and their components’ functionality and application across multiple
vehicle architectures and platforms are increased.
The proper selection and adaptation of field load spectra and profiles to the specific program ensure
functionality, reliability and braking system availability. This document defines a library of field load
schedules to help developing simulation and testing programs tailored to the vehicle or system specification
and requirements. Specific cycles and load collectives including the main functions associated with everyday
driving and operation and exceptional load cases are described to ensure safe braking behaviour. This
document's field load was typically derived from analysing field data collected from more than 1 million
vehicles having driven more than 70 000 000 000 km. Several vehicle and brake system suppliers from
vehicles used in different regions worldwide contributed to this field data collection. In addition, data from
driving studies with specific measurement equipment was used. Wherever the data available from field or
studies was not sufficient, existing specifications or expert judgement served to derive conservative
assumptions.
This document provides field loads independent of the vehicle technology, vehicle specification, intended use
and field usage. It remains the manufacturer's responsibility to include and adapt the field loads to the specific
vehicle configuration. The adaptation at least:
— — defines sampling and testing plans, including vehicle configuration(s), road conditions selection of the
specific profiles and load spectra of this document;
— — defines level of evaluation and integration of simulation, Hardware-in-the-Loop, physical testing
methods, along with other components and software functions part of the testing program;
— — agrees on performance and reliability criteria (including statistical tools and metrics);
— — reflects specific system architectures and control technologies for the unit(s) under testing.
v
ISO/DISFDIS 5101:20242025(en)
Road vehicles — Field load specification for brake actuation and
modulation systems
1 Scope
This document specifies expected field loads for functions provided by the braking system actuator and
modulator and applies to passenger cars and light commercial vehicles (classes M1 and N1, according to
UNECE).
Functions addressed in this document are:
— — dynamic stability functions (e.g. electronic stability control);
— — brake torque optimizing functions (e.g. electronic brake force distribution);
— — brake assistance functions (e.g. hill start assist).
This document only covers functions where data of appropriate maturity are available. There are additional
functions of a braking system, which are not covered by this document.
By describing the expected field loads, this document specifies representative manoeuvres and occurrences
for different functions. These serve as an orientation for the derivation of test procedures.
This document applies to vehicles up to conditional automation (SAE J 3016 level 3).
NOTE Field loads for automation levels above level 3 are under consideration for future editions.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 3.1
blending
applying the driver-requested torque by combining the available regenerative brake torque and friction
torque
3.2 3.2
brake booster
part of the actuation unit, excluding master cylinder, in systems with separate actuator and modulator
Note 1 to entry: A brake booster is not part of braking systems with integrated actuator and modulator (see
Figure 2Figure 2).).
ISO/DISFDIS 5101:20242025(en)
3.3 3.3
brake friction coefficient
ratio between the tangential force and the normal force, acting between linings and drum or disc
[SOURCE: ISO 611:2003, 9.19.1, modified — The symbols and formula were removed, the original term was
"coefficient of friction".]
3.4 3.4
coefficient of adhesion
µ
ratio between the tangential force transmitted to the road by a tyre and the normal force
[SOURCE: ISO 611:2003, 9.19.2, modified — "k" was changed to "µ", the symbols, formula and note were
removed.]
3.5 3.5
complete vehicle kerb mass
complete vehicle shipping mass plus the mass of the following elements:
— — lubricants,
— — coolant (if needed)),
— — washer fluid,
— — fuel (tank filled to at least 90 % of the capacity specified by the manufacturer)),
— — spare wheel(s)),
— — fire extinguisher(s)),
— — standard spare parts,
— — chocks,
— — standard tool-kit
[SOURCE: ISO 1176:1990;, 4.6]
3.6 3.6
fading
decrease of braking torque as a function of temperature or vehicle speed at constant application force
Note 1 to entry: Amongst others, the decrease of the friction by the temperature is the most important effect.
[SOURCE: ISO 611:2003, 7.1.7, modified — The original term was "brake fade", the word “vehicle” and Note 1
to entry were added, and the examples were removed.]
3.7 3.7
fully active brake operation
deceleration intended by the driver and automatically initiated and operated by the braking system
3.8 3.8
function control time
durationamount of time the function is controlling the braking force
ISO/DISFDIS 5101:20242025(en)
Note 1 to entry: The function control time does not include the brake apply-, release-, hold- or modulation-duration in
case of partially active brake operation (3.14.).
3.9 3.9
manoeuvre duration
duration the braking system is controlling the braking force
Note 1 to entry: See Figure 1.
Note 2 to entry: For some functions, the function control time (3.8SEE: Figure 1

) is identical to the manoeuvre duration, e.g. ACC.

Key
p brake pressure [kPa]
t elapsed time [s]
p brake pressure [kPa]
ISO/DISFDIS 5101:20242025(en)
t elapsed time [s]
NOTE 1 In this example the function control time (3.8(3.8)) is shorter than the manoeuvre duration.
NOTE 2 The braking force is visualized as brake pressure.
Figure 1 — Example for manoeuvre duration incl.including ABS
Note 1 to entry: For some functions, the function control time (3.8) is identical to the manoeuvre duration e.g., ACC.
3.10 3.10
maximum design pay mass
figure obtained by subtracting the complete vehicle kerb mass (3.5(3.5)) from the maximum design total mass
(3.11(3.11),), with mass of driver excluded
[SOURCE: ISO 1176:1990;, 4.9]
3.11 3.11
maximum design total mass
maximum vehicle mass as defined by the vehicle manufacturer
[SOURCE: ISO 1176:1990;, 4.7, modified — "This mass may be greater than the maximum total mass
authorized by national administrations (see also notes in term )”” was removed.]
3.12 3.12
mean steer angle
average of the left- and right-hand steer angles on the same axis
Note 1 to entry: Rear-wheel steering is not considered in this document.
[SOURCE: ISO 8855:2011, 7.1.3, modified — The variable δ and accepted term "mean road wheel steer angle"
m
were removed, "axle" was replaced by "axis" and Note 1 to entry was added.]
3.13 3.13
nominal runout pressure
lowest master cylinder pressure where maximum support from the actuator is reached in quasi-static
operation
Note 1 to entry: Only applies to separated actuator and modulator.
Note 2 to entry: For vacuum-based actuation systems, the nominal runout pressure refers to sea level.
Note 3 to entry: Above this pressure, only the unsupported pressure increase is possible.
3.14 3.14
partially active brake operation
deceleration initiated by the driver and supported by the modulation of the wheel brake pressure
3.15 3.15
regenerative capacity
maximum available regenerative brake torque at a certain point in time
3.16 3.16
standstill
stopping situation during a trip (3.17) in which the vehicle is not moving
EXAMPLE Stopping at traffic lights or in heavy traffic situations.
ISO/DISFDIS 5101:20242025(en)
Note 1 to entry: Standstill does not include parking situations.
3.17 3.17
trip
drive event starting with driving off and ending with parking the vehicle
Note 1 to entry: A trip does not include wake up cycles of the brake system while parking.
3.18 3.18
typically laden
complete vehicle kerb mass (3.5(3.5)) plus 50 % of the maximum design pay mass (0(3.10)) or plus 200 kg,
whichever is higher
4 General
This document describes use cases represented by manoeuvres and their occurrences for various functions of
the braking system to describe the expected field loads for a braking system. Unless otherwise specified, these
manoeuvres and occurrences are derived from empirical values and collected field data.
The manoeuvres and occurrences described in this document serve as an orientation to develop test
procedures. The specific braking system and vehicle configuration should be considered to determine the
applicability of the generalized field loads detailed in this document.
Figure 2Figure 2 depicts the components of the braking system addressed in this document.
ISO/DISFDIS 5101:20242025(en)
Figure 2 — Components of the braking system
5 Percentiles of field coverage
The braking system supports multiple vehicle dynamics functions. The probability of high usage of all
functions in an individual vehicle is much lower than the probability of high usage of only one single function
th
in an individual vehicle. A specification aiming to cover the 100 percentile vehicle for every individual
function would lead to an over-specification.
The field load for the base brake function, electronic brake force distribution (EBD), antilock braking system
th
(ABS) and adaptive cruise control (ACC) aims to describe the 99 percentile vehicle usage. All other functions
ISO/DISFDIS 5101:20242025(en)
th
described in 7Clause 7 cover the 95 percentile vehicle usage for each function. However, it is unlikely that all
functions – given the multitude of functions – are used up to the specification limit in one individual vehicle.
This approach leads to a field coverage significantly above 99 %.
th
NOTE 1 The base brake function, EBD, ABS and ACC are specified to cover the 99 percentile vehicle usage because
products only providing this set of functions exist and therefore, the combination effect is weak. ACC is specified to cover
th
the 99 percentile because it is an automation of the standard braking function.
Figure 3Figure 3 illustrates an example of the usage of an individual function.
ISO/DISFDIS 5101:20242025(en)
Key
σ load or stress level with consistent engineering units
P probability density
th
a 99 percentile
σ load or stress level with consistent engineering units
P probability density
th
a 99 percentile
Figure 3 — Schematic example of the probability density function P for the load σ
ISO/DISFDIS 5101:20242025(en)
NOTE 2 Few vehicles experience a very low load; few vehicles experience a very high load; most vehicles experience
a medium level of load.
NOTE 3 Typically, braking system components can endure loads above their specification. Furthermore, the load a
component experiences is typically lower than the load described.
6 Base assumptions and boundary conditions
6.1 General
This clause defines the assumptions for the vehicle lifetime and braking system lifetime. These assumptions
serve as the baseline for the manoeuvres and occurrences of the functions described in 7Clause 7.
NOTE 7Clause 7 describes the field load for braking system functions but not for wearing parts such as brake pads
and brake discs.
6.2 Lifetime specifications
6.2.1 Vehicle lifetime
The field loads described in this document correspond to a vehicle lifetime of either 300 000 km or 8 000 h of
trip duration or 15 years, whichever occurs first.
The expected amount of trips is up to 50 000 over a vehicle lifetime.
6.2.2 Standstill events, slopes and durations
The expected amount of brake operations that lead to a standstill is 480 000 over a vehicle lifetime.
Table 1Table 1 shows the distribution of slopes at the standstill events. The values shown include uphill and
th
downhill slopes and cover the 99 percentile. An even distribution between up- and downhill situations is
assumed.
Table 1 — Distribution of standstill events versus slope
Slope at a standstill Probability
[%] [%]
>30 - 50 0,006
>20 - 30 0,194
>15 - 20 0,8
>10 - 15 2
>5 - 10 9
≤5 88
6.2.3 Standstill duration distribution
In total 480 000 standstill events are defined over vehicle lifetime. Table 2Table 2 shows the distribution of
their duration. The durations are independent of any active function during a trip. The distribution covers the
th
99 percentile usage.
NOTE The parking times between two trips are not considered.
ISO/DISFDIS 5101:20242025(en)
Table 2 — Distribution of standstill duration
Standstill duration
Frequency
[s]
0 - 2 126 000
2 - 10 162 000
10 - 30 100 000
30 - 60 47 000
60 - 180 34 000
180 - 900 9 000
>900 2 000
Sum 480 000
6.2.4 Brake duration distribution
Table 3Table 3 shows values of the brake duration distribution of an average driver while the vehicle is in
motion and inat a standstill.
Table 3 — Distribution of brake duration while vehicle in motion and inat a standstill
Brake duration Percentage per class
[s] [%]
0 - 2 57
2 - 5 25
5 - 10 9
10 - 60 8
>60 1
Sum 100
Table 4Table 4 shows values of the brake duration distribution of an average driver while the vehicle is in
motion.
Table 4 — Distribution of brake duration while vehicle in motion
Brake duration while driving Mean brake duration Percentage per class
[s] [s] [%]
0 - 2 1,5 47
>2 - 3 2,6 16
>3 - 5 4,0 14
>5 - 10 6,2 16
>10 14,5 7
NOTE 1  The expected total brake duration over vehicle lifetime of an average driver is 640 h.
NOTE 2  The expected total amount of brake operations while driving over vehicle lifetime of an average driver is 625 000.
ISO/DISFDIS 5101:20242025(en)
6.2.5 Distribution of lateral acceleration
The expected total time spent in the lateral acceleration class over vehicle lifetime is shown in Table 5Table 5.
th
The data represents the 95 percentile vehicle for each class.
Table 5 — Distribution of lateral acceleration
Total time spent in the lateral acceleration class over
Lateral acceleration
vehicle lifetime
[m/s ]
[s]
>8,0 50
>5,0 - 8,0 7 100
>3,0 - 5,0 200 000
>2,0 - 3,0 525 000
>1,0 - 2,0 1 550 000
NOTE 1  Lateral acceleration below 1,0 m/s has little relevance for the specification of brake system functions and is therefore
omitted.
NOTE 2  The table shows absolute values of lateral acceleration for the sake of simplicity a symmetrical distribution between left-
and right-hand turns can be assumed.
6.2.6 Vehicle speed at the beginning of braking events
The distribution of the vehicle speed at the beginning of braking events, using the average of the field data, is
shown in Table 6Table 6.
Table 6 — Distribution of vehicle speed at the beginning of braking events
Velocity Probability Cumulated probability
[km/h] [%] [%]
>0 - 5 9 9
>5 - 10 12 21
>10 – 20 15 36
>20 – 30 12 48
>30 – 40 12 60
>40 – 50 10 70
>50 – 60 8 78
>60 – 70 7 85
>70 – 80 4 89
>80 – 90 2 91
>90 – 100 2 93
>100 – 110 2 95
>110 5 100
NOTE  The distribution covers all braking events during forward and backward driving.
ISO/DISFDIS 5101:20242025(en)
6.3 Number of brake operations
th
Over a vehicle lifetime, the 99 percentile of brake operations corresponds to 2,2 million brake operations. Of
these 2,2 million brake operations, 600 000 events take place during standstill.
The frequency of brake operations during standstill represents brake operations that begin and end during
vehicle standstill.
Table 7Table 7 shows the number of brake operations in deceleration classes of 0,05 g.
The frequencies shown in Table 7Table 7 include the base brake function and all functions intended to
decelerate or hold the vehicle.
This document assumes 10 000 kPa is equivalent to 1,0 g for a typically laden vehicle. In case vehicle-specific
data for the expected loading conditions is available, that should be used instead of the typically laden
conditions defined in this document.
Table 7 — Distribution of brake operations versus deceleration and brake pedal force
Brake pedal
Frequency
Deceleration Frequency per class Frequency
force
per class during
a
[g] while driving per class
standstill
[N]
0,00 ≤ x ≤ 0,05 20 205 033 84 569 289 602
0,05 < x ≤ 0,10 20 639 927 243 706 883 633
0,10 < x ≤ 0,15 29 404 300 115 070 519 370
0,15 < x ≤ 0,20 38 200 177 56 182 256 359
0,20 < x ≤ 0,25 48 84 266 25 350 109 616
0,25 < x ≤ 0,30 57 35 147 16 912 52 059
0,30 < x ≤ 0,35 67 14 463 12 771 27 234
0,35 < x ≤,0,40 77 7 168 9 810 16 978
0,40 < x ≤ 0,45 86 3 893 7 793 11 686
0,45 < x ≤ 0,50 96 2 144 5 892 8 036
0,50 < x ≤ 0,55 105 1 252 4 585 5 837
0,55 < x ≤ 0,60 115 745 3 474 4 219
0,60 < x ≤ 0,65 124 466 2 718 3 184
0,65 < x ≤ 0,70 134 332 2 218 2 550
0,70 < x ≤ 0,75 143 198 1 613 1 811
0,75 < x ≤ 0,80 153 91 1 067 1 158
0,80 < x ≤ 0,85 163 77 995 1 072
0,85 < x ≤ 0,90 172 63 917 980
0,90 < x ≤ 0,95 182 52 831 883
0,95 < x ≤ 1,00 191 41 739 780
1,00 < x ≤ 1,05 201 32 640 672
1,05 < x ≤ 1,10 210 25 534 559
1,10 < x ≤ 1,15 220 19 421 440
ISO/DISFDIS 5101:20242025(en)
Brake pedal
Frequency
Deceleration Frequency per class Frequency
force
per class during
a
[g] while driving per class
standstill
[N]
1,15 < x ≤ 1,20 230 14 301 315
1,20 < x ≤ 1,25 239 10 175 185
1,25 < x ≤ 1,30 249 9 105 114
> 1,30 > 250 56 612 668
1 600 000 600 000 2 200 000
a Including brake operations leading to a vehicle standstill.
NOTE 1 Table 7Table 7 shows data over a vehicle lifetime according to 6.2.16.2.1.
NOTE 2 Brake pedal forces are derived from the deceleration to brake pedal force characteristic of vehicles which
delivered the corresponding field data.
NOTE 3 Brake pedal forces values are used for brake pedal applies during standstill, deceleration values for brake
pedal applies during driving.
NOTE 4 For vehicle configurations differing from those assumptions, the relation between brake pressure and
deceleration is determined individually.
Figure 4Figure 4 illustrates the corresponding cumulative distributions from Table 7Table 7.
ISO/DISFDIS 5101:20242025(en)
Key
X cumulative number of load cycles in counts
g deceleration level in g
1 total cumulative brake operations
2 cumulative brake operations while driving
3 cumulative brake operations during standstill
X cumulative number of load cycles in counts
g deceleration level in g
ISO/DISFDIS 5101:20242025(en)
1 total cumulative brake operations
2 cumulative brake operations while driving
3 cumulative brake operations during standstill
Figure 4 — Cumulative distribution per class
6.4 Temperature distributions
6.4.1 Global environmental temperature distribution T
env
This document considers the following temperatures to define the probability for Table 8Table 8::
— — for the coldest locations with 1 % of population at -40 °C, -30 °C and -20 °C;
— — for the hottest locations with 1 % of population at 30 °C, 40 °C and 50 °C;
— — for the rest of the population at -10 °C, 0 °C, 10 °C and 20 °C;
— — weighting according to human population density;
— — cities with less than 1 000 inhabitants are not considered;
— — extreme temperature events, which do not occur regularly within 10 years, are not covered.
Table 8 — Distribution of environmental temperature
Tenv Probability
[°C] [%]
‒40 0,5
‒30 2
‒20 5
‒10 5
0 7,5
10 15
20 25
30 25
40 14
50 1
Sum 100
6.4.2 Temperature distribution at mounting location T
mount
6.4.2.1 General
The temperature at mounting location T reflects the superposition of the environmental temperature T
mount env
outside the vehicle with the temperature increase ΔT at the mounting location in a motor or engine
compartment during vehicle operation.
Use Error! Reference source not found. to determine the temperature distribution at the mounting location.
T = T + ΔT (1)
mount env
ISO/DISFDIS 5101:20242025(en)
where
T is the temperature at the mounting location of the brake actuation and modulation systems;
mount
T is the distribution of worldwide environmental temperature outside the vehicle (vehicle
env
independent, see 6.4.1);
ΔT is the temperature increase by vehicle usage at mounting location (vehicle dependent, typical
vehicle resulting distribution for T given in 6
T is the temperature at the mounting location of the brake actuation and modulation systems;
mount
T is the distribution of worldwide environmental temperature outside the vehicle (vehicle
env
independent, see 6.4.1);
ΔT is the temperature increase by vehicle usage at mounting location (vehicle dependent, typical
vehicle resulting distribution for T given in Clause 6).
).
At environmental temperatures of -40 °C, no increase of T by vehicle usage is assumed due to the airflow's
mount
high cooling capability.
6.4.2.2 Temperature distribution for vehicles with internal combustion engine
6.4.2.2.1 Distribution of temperature at mounting location
Table 9Table 9 provides the estimated probability distribution as a function of the temperature at the
mounting location T .
mount
Moderate and high environmental temperatures lead to a ΔT of up to 55 K.
Specific temperature effects may be considered when the brake system components directly interact (have
thermal conductivity) through a mechanical connection.
EXAMPLE Direct cooling effect by the connection of an actuator to the passenger compartment.
Table 9 — Distribution of temperature at the mounting location
Tmount Probability
[°C] [%]
‒40 0,5
‒20 2,5
20 28
60 40
80 26
105 3
Sum 100
The entire temperature sequence should be repeated.
NOTE Repetition of the entire temperature sequence avoids over-simplification.
6.4.2.2.2 Exceptional high temperatures at the mounting location
Higher ΔT can occur as a combination of exceptional events and devices' proximity with significantly increased
temperatures.
ISO/DISFDIS 5101:20242025(en)
EXAMPLE Stopover after long steep uphill driving at low speed with fully laden trailer and vehicle.
NOTE 1 This occurs only in rare vehicle configurations.
To also cover such exceptional situations, Figure 5Figure 5 shows representative manoeuvres, including
120 °C.
Phase 1 defines the starting condition. The braking system is heated thoroughly until 105 °C to ensure all
system components start with this initial temperature.
Phase 2 represents the heat-up phase. During this time, with a minimum of 300 s, T shall increase to 120 °C
mount
with a constant temperature gradient.
Phase 3 represents the application and cool-down phase. During this time frame of at least 600 s, apply
10 actuations at 0,15 g and 10 actuations at 0,35 g deceleration requests. These actuations are applied by
input from the brake pedal or as a fully automatic brake operation, whichever mode induces the system's
higher load. The pressure cycle shall follow the ACC-16 and ACC-35 profiles. Distribute the brake applications,
including the corresponding pause times, evenly over time. The mounting temperature of the braking system
shall decrease to 105 °C with a constant temperature gradient.
Repeat this procedure a total of 15 times to simulate one occurrence of this situation once every year over a
vehicle lifetime.
Due to the rare occurrence, any combination with other conservative assumptions (e.g. extreme frequency of
use) is not expected.
ISO/DISFDIS 5101:20242025(en)
Key
T temperature at the mounting location in °C
mount
t elapsed time [s]
1 conditions for start
2 heat-up phase
3 application and cool-down phase
T temperature at the mounting location in °C
mount
t elapsed time [s]
ISO/DISFDIS 5101:20242025(en)
1 conditions for start
2 heat-up phase
3 application and cool-down phase
Figure 5 — Representative manoeuvre for extreme temperatures at the mounting location
NOTE 2 The temperature gradients in phase 2 and phase 3 allow the braking system to reach the temperature it is
expected to be subjected to in its mounting location.
6.4.2.2.3 Function specific occurrence and distributions over temperature ranges
6.4.2.2.3.1 General
Table 10Table 10 shows neglectable occurrences of T /manoeuvre combinations as indicated by "-".
mount
Expected occurrences of T /manoeuvre combinations are indicated by "x". Table 10Table 10 only lists
mount
manoeuvres that typically would not occur at all indicated temperature ranges.
The total required number of specified events for a function should not be reduced.
NOTE The manoeuvres shown in Table 10Table 10 are described in 7Clause 7.
Table 10 — T dependent occurrence of manoeuvres
mount
Function Manoeuvre Tmount < –20 °C –20 °C ≤ Tmount ≤ 80 °C Tmount > 80 °C
Cold start Cold start 1 x x -
Cold start 2 x x -
ABS ABS 1 x x -
ABS 4 x x -
ABS 5 L x x -
ABS 5 R x x -
ABS 7 x x -
HRB HRB 1 - x x
HRB 2 - x x
HBA HBA 5 - x x
Fading Fading 1 - x x
Fading 2 - x x
TCS ORD TCS ORD 1a - x x
TCS ORD 1b - x x
TCS ORD 2a - x x
TCS ORD 2b - x x
TCS ORD 3a - x x
TCS ORD 3b - x x
BDW BDW - x x
Key
ABS      Antilock braking system
HRB     Hydraulic rear-brake boost
ISO/DISFDIS 5101:20242025(en)
Function Manoeuvre T < –20 °C –20 °C ≤ T ≤ 80 °C T > 80 °C
mount mount mount
HBA     Hydraulic brake assist
TCS ORD Traction control for off-road
BDW     Brake disc wiping
Manoeuvres with a calculated occurrence of less than one activation in a temperature class can be omitted.
Manoeuvres with an occurrence of fewer than 10 activations in a temperature class can be carried out by load
equivalent manoeuvres at the same temperature. The loss of accuracy is negligible.
6.4.2.2.3.2 Background
T > 80° °C: Atat environmental temperatures > 25° °C it is unlikely to run low muedue to ABS control
mount
(T = T + ΔT) with ΔT of up to 55 K. T = 25 °C + 55K55 K = 80 °C.
mount env mount
T < -20° °C: Itit is unlikely to have brake fading or driving in extreme off-road at low temperature in the
mount
surrounding of the brake system.
6.4.2.3 Temperature distribution for electric vehicles
6.4.2.3.1 Distribution of temperature at mounting location
Table 11Table 11 provides the estimated probability distribution as a function of the temperature at the
mounting location T .
mount
Moderate and high environmental temperatures lead to a ΔT of up to 35 K.
Specific temperature effects may be considered when the brake system components directly interact (have
thermal conductivity) through a mechanical connection.
EXAMPLE Direct cooling effect by the connection of an actuator to the passenger compartment.
Table 11 — Distribution of temperature at the mounting location for electric vehicles
Tmount Probability
[°C] [%]
‒40 0,5
‒20 8
20 44
40 32
60 15
85 0,5
Sum 100
The entire temperature sequence should be repeated.
NOTE Repetition of the entire temperature sequence avoids over-simplification.
ISO/DISFDIS 5101:20242025(en)
6.4.2.3.2 Function specific occurrence and distributions over temperature ranges
6.4.2.3.2.1 General
Table 12 12 shows neglectable occurrences of T /manoeuvre combinations as indicated by "-". Expected
mount
occurrences of T /manoeuvre combinations are indicated by "x". Table 12 12 only lists manoeuvres that
mount
typically would not occur at all indicated temperature ranges.
The total required number of specified events for a function should not be reduced.
NOTE The manoeuvres shown in Table 12 12 are described in 7.
Table 12 — T dependent occurrence of manoeuvres for electric vehicles
mount
Function Manoeuvre Tmount < –20 °C –20 °C ≤ Tmount ≤ 60 °C Tmount > 60 °C
ABS ABS 1 x x -
ABS 4 x x -
ABS 5 L x x -
ABS 5 R x x -
ABS 7 x x -
HRB HRB 1 - x x
HRB 2 - x x
HBA HBA 5 - x x
Fading Fading 1 - x x
Fading 2 - x x
TCS ORD TCS ORD 1a - x x
TCS ORD 1b - x x
TCS ORD 2a - x x
TCS ORD 2b - x x
TCS ORD 3a - x x
TCS ORD 3b - x x
BDW BDW - x x
Manoeuvres with a calculated occurrence of less than one activation in a temperature class can be omitted.
Manoeuvres with an occurrence of fewer than 10 activations in a temperature class can be carried out by load
equivalent manoeuvres at the same temperature. The loss of accuracy is negligible.
6.4.2.3.2.2 Background
T > 60° °C: Atat environmental temperatures > 25° °C it is unlikely to run low muedue to ABS control
mount
(T = T + ΔT) with ΔT of up to 35 K. T = 25 °C + 35K35 K = 60 °C.
mount env mount
T < -20° °C: Itit is unlikely to have brake fading or driving in extreme off-road at low temperature in the
mount
surrounding of the brake system.
ISO/DISFDIS 5101:20242025(en)
6.5 Brake pedal application profile
6.5.1 Parameters for brake pedal apply and release time
6.5.1.1 General
A typical apply and release time of 650 ms is assumed independent of the braking event's target pressure. The
typical application time is from the onset of brake pedal application until pressure reaches 90 % of the first
local maxima (t ). The typical release time is from the time pressure reduces to 90 % of the last local maxima
a-90
until the pressure is fully released (t ), see Figure 6Figure 6.
r-90
ISO/DISFDIS 5101:20242025(en)
Key
ISO/DISFDIS 5101:20242025(en)
t time
p brake pressure during brake pedal apply
a
pr brake pressure during brake pedal release
t time from p until p is reached
a-90 a-0 a-90
t time from p until p
r-90 r-90 r-0
a target brake pressure of brake pedal apply
b brake pressure level at beginning of brake pedal release
t time
pa brake pressure during brake pedal apply
p brake pressure during brake pedal release
r
t time from p until p is reached
a-90 a-0 a-90
tr-90 time from pr-90 until pr-0
a target brake pressure of brake pedal apply
b brake pressure level at beginning of brake pedal release
NOTE The profile illustrates a typical manoeuvre, but not the actual gradient during the apply and releases times,
nor results from field data. During the onset of the application or during the end of the release time, the gradient can be
nonlinear due to the actual driver demand, system sizing and the system response at low pressure.
Figure 6 — Example for interpretation of apply and release times
When defining representative pressure profiles for the brake systems function, manufacturers should
consider the typical apply and release times. According to the manufacturer's specific trigger logic, apply the
applicable gradients (rate of change) for functions intended to support the driver during panic braking or
emergencies.
6.5.1.2 Background
The analysis represents field data from more than 570 000 braking events to define typical apply and release
times. The analysis discarded events identified as panic actions before averaging the apply and release times.
6.5.2 Modulation of deceleration during braking events
6.5.2.1 General
Modulation of deceleration during a braking event represents expected driver behaviour. Analysis of field data
indicates one modulation event per braking event on average. The field data also indicates that most
modulation events occur at the end of a braking event and low deceleration.
A suitable representation of this modulation can be implemented by adding a 0,05 g modulation on every
brake release step, as shown in Figure 7Figure 7.
ISO/DISFDIS 5101:20242025(en)
Key
a
maximum deceleration in a brake operation
g vehicle deceleration
t time
a maximum deceleration in a brake operation
g vehicle deceleration
t time
Figure 7 — Example of brake event with modulated braking pedal release
ISO/DISFDIS 5101:20242025(en)
6.5.2.2 Background
Field data representing 660 000 braking events was analysed. Modulation of deceleration is more frequent
during braking events leading to a standstill than during braking events not leading to a standstill. The driver
tends to avoid the stopping jerk by partly releasing the brake pedal and–when a standstill is achieved–pushing
the brake pedal again to ensure a safe standstill. Braking events leading to standstill commonly include
multiple modulations. On the other hand, a significant fraction of braking events not leading to a standstill
does not show any modulation. One modulation per action is the average for events leading to a standstill and
not leading to a standstill.
7 Braking system usage
7.1 Base brake function (BBF)
The load of the base brake function highly depends on the specific braking system configuration.
Therefore, generic manoeuvres cannot be given. Relevant manoeuvres and frequencies can be determined
based on the lifetime specifications (see 6.26.2)) and the brake pedal application profile (see 6.56.5).).
7.2 Base brake function for vehicles with regenerative braking (BBF with recuperation)
7.2.1 General
In most electric vehicles, regenerating components, for example, the electric motor or a flywheel, support
deceleration during braking events. Depending on the deceleration request, the regenerative capacity, and the
regenerating component's characteristics, the regenerative brake torque can partially or fully substitute the
friction brake torque. This substitution can significantly influence the lifetime load and wear for some
components in the brake system and should be reflected in the friction brake activity.
7.2.4Subclause 7.2.4 describes a method to calculate the impact of regenerative braking on a braking system.
This method assumes regenerative braking is functioning and enabled. Failures affecting regenerative braking
operation and extreme use, such as the driver frequently disabling (turning off) the system (intended or
unintended), are not considered.
The technical assessment shall consider scenarios in case discarding or limiting a regenerative action causes
additional load or wear to the braking system or some components.
EXAMPLE The regenerative brake torque is instantly
...