Railway applications - Braking - Relay valves

This document is applicable to relay valves designated to control the brake cylinder pressure of compressed air brakes fitted to railway vehicles, in association with an air brake distributor valve or other control device. It covers one stage relay valves and relay valves adjusting the brake cylinder pressure in response to a change in vehicle speed or load that is either continuously variable or in two or more stages, i.e. empty – loaded.
Relay valves operating with other pressures, in particular the brake pipe pressure, are not included.
This document specifies the requirements for the design, manufacture and testing of relay valves.

Bahnanwendungen - Bremse - Relaisventile

Dieses Dokument gilt für Relaisventile, die zur Steuerung des Bremszylinderdruckes von Druckluftbremsen in Eisenbahnfahrzeugen in Verbindung mit einem Druckluftbremsensteuerventil oder einem anderen Steuergerät bestimmt sind. Es umfasst einstufige Relaisventile und Relaisventile, die den Bremszylinderdruck in Abhängigkeit von einer Änderung der Fahrzeuggeschwindigkeit oder -last, die entweder stufenlos oder in zwei oder mehr Stufen, d. h. leer - beladen, variabel ist, anpassen.
Relaisventile, die mit anderen Betriebsdrücken, insbesondere dem Druck in der Hauptluftleitung, arbeiten, sind hierin nicht erfasst.
In diesem Dokument werden die Anforderungen für die Konstruktion, die Herstellung und die Prüfung von Relaisventilen festgelegt.

Applications ferroviaires - Freinage - Relais pneumatiques

Le présent document s'applique aux relais pneumatiques conçus pour commander la pression au cylindre de frein des freins à air comprimé montés sur des véhicules ferroviaires, conjointement avec un distributeur de frein à air ou un autre dispositif de commande. Il s'applique aux relais pneumatiques à un étage de pression et aux relais pneumatiques qui régulent la pression au cylindre de frein en fonction des variations de la vitesse ou de la charge du véhicule, soit de manière continue, soit par deux étages de pression ou plus, comme les relais vide/chargé.
Les relais pneumatiques fonctionnant avec d'autres pressions, notamment la pression de conduite générale, ne sont pas inclus.
Le présent document spécifie les exigences relatives à la conception, à la fabrication et aux essais des relais pneumatiques.

Železniške naprave - Zavore - Ventili za kontrolo tlaka

General Information

Status
Published
Public Enquiry End Date
26-Oct-2018
Publication Date
20-Apr-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
09-Apr-2020
Due Date
14-Jun-2020
Completion Date
21-Apr-2020

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SLOVENSKI STANDARD
SIST EN 15611:2020
01-junij-2020
Nadomešča:
SIST EN 15611:2009+A1:2011
Železniške naprave - Zavore - Ventili za kontrolo tlaka
Railway applications - Braking - Relay valves
Bahnanwendungen - Bremse - Relaisventile
Applications ferroviaires - Freinage - Relais pneumatiques
Ta slovenski standard je istoveten z: EN 15611:2020
ICS:
23.060.99 Drugi ventili Other valves
45.040 Materiali in deli za železniško Materials and components
tehniko for railway engineering
SIST EN 15611:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 15611:2020
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SIST EN 15611:2020
EN 15611
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2020
EUROPÄISCHE NORM
ICS 45.040 Supersedes EN 15611:2008+A1:2010
English Version
Railway applications - Braking - Relay valves

Applications ferroviaires - Freinage - Relais Bahnanwendungen - Bremse - Relaisventile

pneumatiques
This European Standard was approved by CEN on 13 January 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15611:2020 E

worldwide for CEN national Members.
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SIST EN 15611:2020
EN 15611:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

1 Scope .................................................................................................................................................................... 4

2 Normative references .................................................................................................................................... 4

3 Terms and definitions ................................................................................................................................... 4

4 Symbols and abbreviations ......................................................................................................................... 9

5 Design and manufacture ............................................................................................................................... 9

5.1 General ................................................................................................................................................................ 9

5.2 Functional requirements........................................................................................................................... 11

5.3 Shock and vibration .................................................................................................................................... 16

5.4 Environmental conditions ........................................................................................................................ 16

5.5 Compressed air quality .............................................................................................................................. 18

5.6 Service life ....................................................................................................................................................... 18

5.7 Fire behaviour ............................................................................................................................................... 19

5.8 External appearance ................................................................................................................................... 19

5.9 Design requirements regarding pressure stress .............................................................................. 19

5.10 Interface .......................................................................................................................................................... 19

6 Materials .......................................................................................................................................................... 19

7 Type tests ........................................................................................................................................................ 20

7.1 General ............................................................................................................................................................. 20

7.2 Type test of an individual relay valve ................................................................................................... 20

8 In-service assessment................................................................................................................................. 46

9 Designation..................................................................................................................................................... 46

10 Identification and marking ....................................................................................................................... 46

Annex A (informative) In-service assessment ................................................................................................ 47

A.1 General ............................................................................................................................................................. 47

A.2 Test set-up and sampling .......................................................................................................................... 47

A.3 Procedure........................................................................................................................................................ 47

A.4 Pass/fail criteria ........................................................................................................................................... 47

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2008/57/EC aimed to be covered ..................................................... 48

Bibliography ................................................................................................................................................................. 50

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SIST EN 15611:2020
EN 15611:2020 (E)
European foreword

This document (EN 15611:2020) has been prepared by Technical Committee CEN/TC 256 “Railway

applications”, the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by October 2020, and conflicting national standards shall

be withdrawn at the latest by October 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights

This document supersedes EN 15611:2008+A1:2010.
Compared to the previous edition, the following changes have been made:
a) normative references have been updated;
b) terms and definitions have been revised;
c) requirements on design have been revised;
d) requirements on materials have been revised;
e) requirements on type testing have been revised;
f) requirements on in-service assessment have been revised
g) requirements on markings have been revised;
h) annexes have been revised.

This document has been prepared under a standardization request given to CEN by the European

Commission and the European Free Trade Association, and supports essential requirements of

EU Directive 2008/57/EC.

For relationship with EU Directive 2008/57/EC, see informative Annex ZA, which is an integral part of

this document.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,

Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,

Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
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SIST EN 15611:2020
EN 15611:2020 (E)
1 Scope

This document is applicable to relay valves designated to control the brake cylinder pressure of

compressed air brakes fitted to railway vehicles, in association with an air brake distributor valve or

other control device. It covers one stage relay valves and relay valves adjusting the brake cylinder

pressure in response to a change in vehicle speed or load that is either continuously variable or in two or

more stages, i.e. empty – loaded.

Relay valves operating with other pressures, in particular the brake pipe pressure, are not included.

This document specifies the requirements for the design, manufacture and testing of relay valves.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

EN 14478:2017, Railway applications — Braking — Generic vocabulary

EN 15355:2019, Railway applications — Braking — Distributor valves and distributor-isolating devices

EN 15625:2008+A1:2010, Railway applications — Braking — Automatic variable load sensing devices

EN 45545-1:2013, Railway applications — Fire protection on railway vehicles — Part 1: General

EN 45545-2:2013+A1:2015, Railway applications — Fire protection on railway vehicles — Part 2:

Requirements for fire behaviour of materials and components

EN 50125-1:2014, Railway applications — Environmental conditions for equipment — Part 1: Rolling

stock and on-board equipment

EN 60721-3-5:1997, Classification of environmental conditions — Part 3: Classification of groups of

environmental parameters and their severities — Section 5: Ground vehicle installations

(IEC 60721-3-5:1997)

EN 61373:2010, Railway applications — Rolling stock equipment — Shock and vibration tests

(IEC 61373:2010)

EN ISO 228-1:2003, Pipe threads where pressure-tight joints are not made on the threads —Part 1:

Dimensions, tolerances and designation (ISO 228-1:2000)
ISO 8573-1:2010, Compressed air —Part 1: Contaminants and purity classes
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 14478:2017, EN 15355:2019

and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
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SIST EN 15611:2020
EN 15611:2020 (E)
3.1
relay valve

device, the main function of which is to control a pneumatic output pressure as a function of the variation

of one or more input pressures (see Figure 1)
Key
1 first input pressure
2 second input pressure
3 third input pressure

4 control signal – continuous load sensing pressure (LCP), or control signal – empty/load signal pressure (LSP),

or mechanical input (lever) or electrical input
5 auxiliary reservoir pressure, supply pressure (AR)
6 output pressure
7 relay valve
Figure 1 — Relay valve, pressures and signals
3.2
input pressure
control pressure received by the relay valve

Note 1 to entry: Pressure generally considered as being the output pressure from a distributor or a brake control

unit; sometimes referred to as pilot pressure or dummy brake cylinder pressure.
3.3
output pressure

pressure output from the relay valve, generally considered as being the brake cylinder pressure

Note 1 to entry: This pressure can also be used as the input pressure to another relay valve. The output pressure

can obtain one or more fixed levels or it can be changed continuously between a minimum and a maximum or vice

versa.
3.4
relay valve ratio
ratio of the output pressure value to input pressure value
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SIST EN 15611:2020
EN 15611:2020 (E)
3.5
control signal
signal used to change the relay valve ratio:
— received from the continuous load sensing device (LCP),
— received from empty-loaded changeover device (LSP),
— generated by the position of mechanical changeover,
— generated by other means, e.g. speed dependent
3.6
relay valve type A

relay valve with one fixed relay valve ratio, where the ratio can be less (step-down), equal or greater

(step-up) than 1
3.7
relay valve type B1

relay valve with two or more fixed relay valve ratios that can change during a brake application, where

the ratio can be less (step-down), equal or greater (step-up) than 1

Note 1 to entry: Typically, two stages “empty/load” relay valve, giving an empty (tare) or a loaded output

pressure proportional to input pressure dependant on the load signal input and used on vehicles operated in empty

or fully loaded condition. Alternatively, the ratio can be changed in function of speed.

3.8
relay valve type B2

relay valve with two or more fixed relay valve ratios that cannot change during a brake application, where

the ratio can be less (step-down), equal or greater (step-up) than 1

Note 1 to entry: Typically, two stage “empty/load” relay valve, giving an empty (tare) or a loaded output pressure

proportional to input pressure dependant on the load signal input. Blocking the relay valve ratio during brake

application is typically used to avoid frequent changeovers taking place on vehicles operated near the changeover

weight.
3.9
relay valve type C1

one stage relay valve with a continuously changeable relay valve ratio, where a load signal is used to

change the ratio
3.10
relay valve type C2

relay valve with a continuously changeable relay valve ratio, where a load signal is used to change the

ratio and with a multi-stage feature added

Note 1 to entry: Typically, a load signal is used to change the relay valve ratio and a control signal (automatic or

manual) is used to change the stage(s). The typical result is that at the same load and input pressure, in the lower

stage (e.g. P-mode, passenger train) results a lower output pressure and in a higher stage (e.g. R-mode, rapid

passenger train) this results in a higher output pressure.
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SIST EN 15611:2020
EN 15611:2020 (E)
3.11
function D for a relay valve
overlay function to relay valve type A, C1, C2 with two or more input pressures

Note 1 to entry: In this case the type of the relay valve is respectively AD, C1D and C2D.

3.12
relay valve type E

variable load relay valve with a special, non-linear characteristic, which automatically comes into

operation when the vehicle has more than a certain load

Note 1 to entry: The E type may be a combination of a C1 or C2 type and an additional functional block, or may

be a specific generic design. This function reduces (in comparison with a linear characteristic) the output pressure

for low input pressures to a certain level to limit the heat impact to the wheels during continuous braking.

3.13
sensitivity

change of input pressure causing a variation of output pressure, when the change of input pressure is in

the same direction, with no overshoot or reversal
3.14
initial sensitivity

change of input pressure, starting at 0 bar, which causes the output pressure to start increasing

(see Figure 2)
3.15
sensitivity at reversal

change of input pressure causing a variation of output pressure, when the input pressure is changing

from increasing to decreasing (see Figure 2)
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SIST EN 15611:2020
EN 15611:2020 (E)
3.16
hysteresis

difference in output pressure with the same input pressure, first rising to a value and then, having been

taken past that value, subsequently falls to the same value (see Figure 2)
Key
1 initial sensitivity
2 hysteresis
3 sensitivity at reversal

NOTE The figure is simplified for illustrative purposes, e.g. the real pressure development is not shown.

Figure 2 — Hysteresis and sensitivity
3.17
normal litre

unit of amount of a gas equal to the amount of 1 l at a pressure of 1,00 bar and at a standard temperature,

at 20 °C
Note 1 to entry: Air flow is often stated in normal litres per minute (Nl/min).
3.18
matched pair

combination of a distributor valve and one or more relay valves to achieve specific tolerances of brake

cylinder pressure and timings

Note 1 to entry: The combination is usually kept together throughout the lifetime of the components.

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SIST EN 15611:2020
EN 15611:2020 (E)
4 Symbols and abbreviations

For the purposes of this document, the symbols and abbreviations given in Table 1 apply.

Table 1 — Symbols and abbreviations
Symbol Designation Unit
p pressure bar
input pressure bar
output pressure bar
t time s
AR auxiliary reservoir pressure, supply pressure bar
BCP brake cylinder pressure bar
LCP control signal – continuous load sensing pressure bar
LSP control signal – empty/load signal pressure bar
5 Design and manufacture
5.1 General

A relay valve shall enable a distributor valve or a brake control unit to be used without any vehicle specific

modification to the distributor or the brake control unit, related to the brake cylinder volume. This

includes the independence of the brake application and release times, the inshot feature and the output

pressure development for any output (brake cylinder and piping) volume.

The use of a relay valve shall not alter any of the characteristics of the distributor and/or a brake control

unit that are not specified in this standard.

The use of a relay valve shall enable the brake cylinder pressure to be maintained between prescribed

limits. These limits may be defined by different brake modes or speed-dependent requirements or where

there is a requirement to maintain a nominal constant brake performance irrespective of load.

Table 2 below provides a description of relay valve types described in this standard in comparison to

EN 15611:2010.
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SIST EN 15611:2020
EN 15611:2020 (E)
Table 2 — Relay valve types
Basic type Design Optional additional Type Type
variants function
(EN 15611:2010) (new)
adaptable by none A A
one fixed ratio of diameters of
output/input pistons
multi input for “select
— AD
pressures or adjustable
high”
by screw
adaptable by ratio can change during
B1 B1
more than one fixed
diameters of brake application
ratio of output/ input
pistons
ratio cannot change
or adjustable
pressures
B2 B2
during brake application
by screw
none C C1
with a multi stage
C1 C2
feature added
two input pressures for
variable load relay
D C1D
“select high”
valve
two input pressures for
“select high”
D C2D
with a multi stage
feature added
variable load relay
special nonlinear
valve with kinked
characteristic (kink E E
valve)
characteristics

A multi stage relay valve with only two stages giving output pressures corresponding to empty or laden

vehicle can be named empty/load relay valve.

The E type may be a combination of a C1 or C2 type and additional functional block, or may be a specific

generic design.

The adjustment range of the output pressure for adjustable by screw, adaptable by the diameter of the

piston and variable load relay valves should be from 0,50 bar to 6,00 bar.

Adjustment of the maximum output pressure of a relay valve adjustable by screw should be achieved

without changing internal parts and be accessible without dismantling the device. However, an easily

removable protective device should be installed.

For a defined adjustment of a certain spring, the setting of the stops for low and high output pressures of

a variable load relay valve should be achieved without changing internal parts and be accessible without

dismantling the device. However, an easily removable protective device should be installed.

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SIST EN 15611:2020
EN 15611:2020 (E)
5.2 Functional requirements
5.2.1 General
The requirements shall be tested as given by Table 5.
5.2.2 Minimum output pressure

The specific minimum output pressure of a relay valve as response to a first brake step with an input

pressure of (0,75 ± 0,02) bar shall have a fixed value, defined by its documentation.

Figure 3 gives an example of the output pressure of a relay valve for different conditions of vehicle load.

Key
1 empty condition
2 loaded condition
3 input pressure (0,75 ± 0,02) bar
4 minimum output pressure loaded
5 minimum output pressure empty
NOTE The shown characteristic is an option.

Figure 3 — Example of the output pressure p of a relay valve (brake cylinder pressure) in

relation to the input pressure p for different conditions of vehicle load
5.2.3 Accuracy of the output pressure and changeover
5.2.3.1 General (all types)

The output pressure of the relay valve shall be within the following tolerances, related to the minimum

(empty)/maximum (loaded) figures, given by the type plate and the installation drawing of the relay

valve:

— ± 0,10 bar for nominal output pressures ≤ 3,80 bar at an input pressure of (3,80 ± 0,02) bar

(ratios ≤ 1);

— ± 0,15 bar for nominal output pressures > 3,80 bar at an input pressure of (3,80 ± 0,02) bar

(ratios > 1).
A relay valve may change from a ratio < 1 in empty to > 1 in loaded status.
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SIST EN 15611:2020
EN 15611:2020 (E)

5.2.3.2 Accuracy of the changeover of a multi-stage relay valve (types B1 and B2)

The relay valve shall be designed to changeover from the empty (low), to intermediate (if applicable),

and to the loaded (high) condition and reverse, as defined in 5.2.4, at specified values of the control signal

such as load signal pressure or load sensing pressure (LSP/LCP) or with a mechanical changeover. The

accuracy of the changeover shall be tested in accordance with 7.2.4.4 (types B1 and B2).

5.2.3.3 Accuracy of the changeover of a variable load relay valve with a multi-stage function

overlaid to the variable load brake function (types C2 and C2D)

It shall be possible at any input pressure and any load control pressure (LCP) to change from a lower to

a higher level of the output pressure or vice versa.

The ratio of the gradient of the output to the input pressures between the higher value of the output

pressure to the lower value shall be constant between first brake step and full service and within a

tolerance of ± 10 % for any load condition; this condition is related to a nominal input pressure of

3,80 bar and shall be initiated by a pneumatic or electric control signal.

The accuracy of the changeover shall be tested in accordance with 7.2.4.10 (types C2 and C2D).

5.2.3.4 Accuracy of the output pressure of a relay valve designed for two or more input pressures

(types AD, C1D and C2D)

The output pressure of the relay valve shall correspond to the highest of the input pressures. The

tolerance of the maximum output pressure values shall be ± 0,10 bar, if the nominal value is ≤ 3,80 bar

and ± 0,15 bar, if the nominal value is > 3,80 bar. In the case where two or more input pressures are

acting simultaneously, the output pressure tolerance shall be ± 0,20 bar, if the nominal value is ≤ 3,80 bar

and ± 0,30 bar, if the nominal value is > 3,80 bar.

The accuracy of the output pressure shall be tested in accordance with 7.2.4.13 (types AD, C1D and C2D).

5.2.3.5 Hysteresis of the output pressure in relation to the load control pressure (types C1, C2,

C1D, C2D)

For relay valves C1, C2 the differences of the output pressure, when load control pressure (LCP) has been

increased or decreased, shall not exceed 0,20 bar if the ratio is ≤ 1 and 0,30 bar if the ratio is > 1.

For a relay valve type C1D, C2D, the differences of the output pressure when load control pressure (LCP)

has been increased or decreased shall not exceed 0,25 bar if the ratio is ≤ 1 and 0,30 bar if the ratio is > 1.

For relay valves C1, C2, C1D, C2D in case that the quotient Delta-BCP/Delta-LCP is greater than 1, the

differences of the output pressure when load control pressure (LCP) has been increased or decreased

shall not exceed 0,30 bar if the quotient is ≤ 1 and 0,40 bar if the ratio is > 1.

The accuracy of the output pressure shall be tested in accordance with 7.2.4.7 (types C1, C2, C1D

and C2D).
5.2.4 Control signal characteristics (types B1, B2, C1, C2, C1D, C2D, E)

The design of the relay valve shall allow interaction with at least one of the following load signal types:

a) manual empty-load signal, where this signal is provided by a lever, either mounted directly on the

relay valve, or remotely operated on the vehicle to manually change from the low to the high output

pressure, or vice versa;

b) pneumatic empty/load signal, where the relay valve shall be designed to operate on receipt of the

relevant signal pressure dependent on the brake system design, as follows:

1) Where the control pressure LSP/LCP is ≤ 0,50 bar this indicates a load that is less than the

switching point and shall cause the relay valve to output its lower ratio. If LSP/LCP pressure

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SIST EN 15611:2020
EN 15611:2020 (E)

is ≥ 3,00 bar this indicates a load greater than the switching point and shall cause the relay valve

to output its higher ratio. Other switching points may be defined by the design documentation.

2) Where the changeover device is supplied from the BCP, the load signal can either be 0 bar and

shall cause relay valve to output its lower output ratio or equivalent to the brake cylinder

pressure and shall cause relay valve to output its higher ratio.

3) Where the changeover device is supplied from the AR, the load signal can either be 0 bar and

shall cause relay valve to output its lower output ratio or equivalent to the AR and shall cause

relay valve to output its higher ratio.

NOTE The signal pressure is typically supplied as a load control signal pressure (LSP) from a manually

operated pneumatic device, e.g. a changeover cock, or an automatic empty-load changeover device.

Alternatively, it is supplied as a continuous load sensing pressure (LCP).

c) variable load signal, i.e. where the load sensing pressure (LCP) comes from an automatic

continuously variable load sensing device (weighing valve) giving continuous load information,

see EN 15625:2008+A1:2010;

d) speed dependent or other control signal, where the pressure settings shall be defined by the design

documentation.

5.2.5 Enabling of a change of relay valve ratio during brake application of a relay valve of

type B1

Whilst the brakes are applied, changes of the control signal shall initiate the change of the relay valve

ratio.

Higher pressure values of the control signal may be required to achieve a change of relay valve ratio for

other than freight applications e.g. for locomotives or multiple units. In this case the pressure values of

the control signal will be higher than the values contained in 7.2.4.5 and the test in 7.2.4.5 shall be

amended to meet the requirements of the specific relay valve application.

5.2.6 Prevention of a change of relay valve ratio during brake application of a relay valve of type

B2 and a variable load relay valve, types C1, C2, C1D, C2D, E

Whilst the brakes are applied with an output pressure ≥ 1,00 bar, changes of the control signal

of ± 0,50 bar shall not initiate a change of the relay valve ratio.
5.2.7 Kinked characteristic of a variable load relay valve (type E)

A variable load relay valve with kinked characteristic may be specified for use on freight wagons with

tread brakes.

A relay valve with a kinked characteristic shall be designed to operate in association with distributor

valves compliant with EN 15355:2019, for use on tread braked wagons of greater braked weight than a

value defined by the relevant documents. The required characteristic shall reduce the output pressure

(BCP) at lo
...

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