ISO 24478:2023/FDAmd 1

ISO 24478:2023/FDAMFDAmd 1:2026(en)
ISO/TC 269/SC 2/WG 1
Secretariat: AFNOR
Date: 2026-08-1110-06
Railway applications — Braking — General vocabulary
AMENDMENT 1
Applications ferroviaires — Freinage — Vocabulaire général
AMENDEMENT 1
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© FDIS stage
ISO 24478:2023/FDAMFDAmd 1:2026(en)
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iii
ISO #####-#:####(X 24478:2023/FDAmd 1(en)
Foreword
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© ISO #### 2026 – All rights reserved
iv
ISO 24478:2023/FDAM 1:2026(en)
Railway applications — Braking — General vocabulary
AMENDMENT 1
Introduction, second paragraph
Replace “may” with “can”:” as shown in the following sentence:
“The braking includes all factors that have a bearing on the stopping, slowing or immobilization performance
of the train (e.g. train resistance, gradient) and can involve the conversion and dissipation of braking energy.”

3.1.1
Add “brake application” as an admitted term.

3.1.2
Change “brake system” to the preferred term and “brake” to the admitted term.

Add noteNote 2 to entry as follows:
“Note 2 to entry: One brake demand (3.9.1.1) is managed by only one brake system.”

3.1.3
Change the definition as follows:
“device or assembly of components, that is the origin of the braking force or torque”

Change noteNote 2 to entry as follows:
“Note 2 to entry: For tread brake and disc brake, the brake unit consists of the brake actuator, the friction
material (pads or block) and the surface on which the friction material applies, but the disc or wheel tread is
part of the brake system.”
3.1.43
Add the following new terminological entries after 3.1.4 as follows:
“3.1.4:
main brake system
trainwide continuous brake system which enables emergency brake application (3.8.1), service brake
application (3.8.2) and parking (3.4.7)
Note 1 to entry: The main brake system can also ensure holding function and immobilizing function.”.

3.1.5
Add new 3.1.5 as follows:
“3.1.5
brake subsystem
combination of brake units and their local control devices, usually per type of brake units (e.g. disc brake
subsystem or electrodynamic brake subsystem)”)

3.3.1
Add admitted term “brake performance” as an admitted term and modifychange the definition as follows:
“braking performance
brake performance
“parameters and their values used to quantify braking by brake system(s) as described in applicable braking
standards”
3.5.4
In the definition, replaceReplace “hold” with “keep” in the definition.

3.5.8, 3.5.97
Add the following new terms and definitionsterminological entries after 3.5.7, and renumber the former 3.5.8
and 3.5.9 to 3.5.10 and former 3.5.9 to 3.5.11, respectively:
“3.5.8
maximum braking payload
maximum payload considered for the design of a brake system, which is lower than or equal to exceptional
payload
3.5.9
design mass under maximum braking payload
MXB
sum of the design mass in working order (as defined by ISO 10516) and maximum braking payload (0(3.5.8))
© ISO #### 2026 – All rights reserved
ISO 24478:2023/FDAMFDAmd 1:2026(en)
Note 1 to entry: In some already published documents the “design mass under maximum braking payload” was also
known as “maximum braking load” ([e.g. in Commission Regulation (EU) No 1302/2014).”].

3.6.7
Change the symbol to "s ".
slw
3.6.8
Change the symbol to "s ".
stp
3.6.14
Add "(3.6.12)" after "delay time":" in the definition as follows:
“period of time commencing at the end of the delay time (3.6.12) and ending when achieving an increase from
a % to b % of the established braking parameter”

3.6.15
Replace "delay time" with "release delay time (3.6.13)":)" in the definition as follows:
“period of time commencing at the end of the release delay time (3.6.13) and ending when achieving a decrease
from c % to d % of the established braking parameter”

3.6.16
Change the definition to:
“sum of the delay time (3.6.12) and the build-up time (3.6.14)”

3.6.17
Change the definition to:
“sum of the release delay time (3.6.13) and the release time (3.6.15)”

3.6.20
Change the symbol to "tslw".
3.6.21
Change the symbol to "tstp".
3.6.28
Change the term to “increasing braking deceleration””.
InDelete “variation in” in the definition, delete “variation in”.

3.6.31
Change the definition and Note 1 to entry to:
“assumed acceleration throughout the equivalent response time (3.6.22), when it is assumed that there is no
braking force applied.
Note 1 to entry: equivalentEquivalent free running acceleration can be different from zero due e.g., for
example, to gradient, rolling resistance, etc.”

3.6.32
Change the term to “equivalent braking deceleration””.

Change the definition and Note 1 to entry to:
“assumed constant deceleration throughout the equivalent braking distance (3.6.10)")
Note 1 to entry: equivalentEquivalent braking deceleration can consider external forces, e.g. forces due to
gradient, rolling resistance, etc. The way how to determine the equivalent braking deceleration is described
in the ISO 20138 series.”
3.6.33
Change the term to “decreasing braking deceleration””.
InDelete “variation in” in the definition delete “variation in”.

3.6.34
Change the symbol to “a or ” and add the symbol“a ””.
stp slw
© ISO #### 2026 – All rights reserved
ISO 24478:2023/FDAMFDAmd 1:2026(en)
3.6.40
Replace "brake performance" by "braking performance (3.3.1)")".

3.6.41
Replace "brake performance" by "braking performance (3.3.1)")".

3.7.1
Replace “brake system” with “brake subsystem””.

3.7.2
Replace “brake system” with “brake subsystem””.

3.7.3
Replace “brake system” with “brake subsystem””.

3.7.3.1
Replace “brake system” with “brake subsystem””.

3.7.3.1.1
Change the definition to:
“force applied by the brake block(s) to the running surface of a wheel (tread)”

Add noteNote 2 to entry as follows:
“Note 2 to entry: For the tread brake, the term “single brake block force” is also used to refer to the brake
application force.”
3.7.3.2
Replace “friction brake system” with “friction brake subsystem””.

3.7.3.2.1
ModifyChange Note 1 to entry to:
“"Note 1 to entry: The sum of all brake pad forces for a brake unit is the brake application force (3.7.6).”)."

3.7.3.2.43
Add a new terminological entry after 3.7.3.2.43 as follows:
“3.7.3.2.4
mean swept radius
distance from the centre of the brake disc to the point where the brake pad force can be considered to be
acting
Note 1 to entry: In some published documents, the mean swept radius of the brake pad on the friction face wasis also
known as brake radius.”.
3.7.3.3
Replace “friction brake system” with “friction brake subsystem””.

3.7.4
Change the term “dynamic brake” to “dynamic brake subsys
...