EN IEC 60136:2024

SLOVENSKI STANDARD
01-september-2024
Mere, označevanje in preskušanje grafitnih ščetk ter mere držal ščetk za električne
stroje (IEC 60136:2024)
Dimensions, marking and testing of carbon brushes and dimensions of brush-holders for
electrical machinery (IEC 60136:2024)
Abmessungen, Kennzeichnung und Prüfung von Kohlebürsten und Abmessungen von
Bürstenhaltern für elektrische Maschinen (IEC 60136:2024)
Dimensions, marquages et essais des balais et dimensions des porte-balais pour
machines électriques (IEC 60136:2024)
Ta slovenski standard je istoveten z: EN IEC 60136:2024
ICS:
29.160.10 Sestavni deli rotacijskih Components for rotating
strojev machines
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60136

NORME EUROPÉENNE
EUROPÄISCHE NORM June 2024
ICS 29.160.10
English Version
Dimensions, marking and testing of carbon brushes and
dimensions of brush-holders for electrical machinery
(IEC 60136:2024)
Dimensions, marquages et essais des balais et dimensions Abmessungen, Kennzeichnung und Prüfung von
des porte-balais pour machines électriques Kohlebürsten und Abmessungen von Bürstenhaltern für
(IEC 60136:2024) elektrische Maschinen
(IEC 60136:2024)
This European Standard was approved by CENELEC on 2024-06-12. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60136:2024 E
European foreword
The text of document 2/2180/FDIS, future edition 3 of IEC 60136, prepared by IEC/TC 2 "Rotating
machinery" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2025-03-12
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-06-12
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60136:2024 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60773:2021 NOTE Approved as EN IEC 60773:2021 (not modified)
ISO 3611 NOTE Approved as EN ISO 3611
ISO 13102:2012 NOTE Approved as EN ISO 13102:2012 (not modified)
ISO 13385-1:2019 NOTE Approved as EN ISO 13385-1:2019 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60276 2018 Carbon brushes, brush holders, EN IEC 60276 2019
commutators and slip-rings - Definitions
and nomenclature
IEC 60560 - Definitions and terminology of brush- - -
holders for electrical machines
ISO 129-1 - Technical product documentation (TPD) - EN ISO 129-1 -
Presentation of dimensions and tolerances
- Part 1: General principles
ISO 197-1 1983 Copper and copper alloys - Terms and - -
definitions - Part 1: Materials
ISO 286-2 2010 Geometrical product specifications (GPS) - EN ISO 286-2 2010
ISO code system for tolerances on linear
sizes - Part 2: Tables of standard tolerance
classes and limit deviations for holes and
shafts
IEC 60136 ®
Edition 3.0 2024-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Dimensions, marking and testing of carbon brushes and dimensions of brush-

holders for electrical machinery

Dimensions, marquages et essais des balais et dimensions des porte-balais

pour machines électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.160.10  ISBN 978-2-8322-8835-1

– 2 – IEC 60136:2024 © IEC 2024
CONTENTS
FOREWORD . 7
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and symbols. 11
3.1 Terms and definitions . 11
3.2 Symbols . 19
4 Units and marking . 21
4.1 Units . 21
4.2 Marking . 21
4.2.1 Units . 21
4.2.2 Additional marks on the brush. 21
4.2.3 Additional marks for brush-holders . 22
5 Principal dimensions and tolerances of brushes. 22
5.1 Sequence . 22
5.2 Standard dimensions . 24
5.3 Tolerances on principal dimensions . 24
5.3.1 General tolerances . 24
5.3.2 Split brushes . 25
5.3.3 Metal-graphite brushes . 26
5.4 Recommended combinations of principal dimensions . 26
5.4.1 Combination for t and a . 26
5.4.2 Square brush . 29
6 Complementary dimensions of brushes . 30
6.1 Chamfers . 30
6.1.1 Angle . 30
6.1.2 Dimension . 30
6.1.3 Non-reversing chamfer . 31
6.2 Angles for contact and top bevels . 32
6.2.1 Angles for contact bevel . 32
6.2.2 Angles for top bevel . 33
6.2.3 Combination of angles . 34
6.3 Pressure area . 34
6.4 Depth of insertion q of the flexible (shunt) in the brush . 35
i
6.5 Residual material width adjacent to the flexible . 36
6.6 Safe length of a worn brush r . 37
m
7 Terminations of brushes: flexibles and terminals. 38
7.1 Flexibles . 38
7.1.1 General . 38
7.1.2 Nominal area and maximum diameter of flexibles . 39
7.1.3 Length of flexible . 40
7.1.4 Flexible protection . 40
7.2 Terminals . 40
7.2.1 General . 40
7.2.2 Axial spade terminals . 41
7.2.3 Flag terminals . 42
7.2.4 Double shoe terminals . 43

IEC 60136:2024 © IEC 2024 – 3 –
7.2.5 Tubular terminals . 44
7.2.6 Soldered terminals . 45
7.2.7 Current capacity of terminals . 46
8 Test procedures for determining physical properties of brushes . 47
8.1 General . 47
8.2 Measurement of electrical resistance of brush/flexible connection . 47
8.2.1 General . 47
8.2.2 Test equipment . 48
8.2.3 Test procedure . 50
8.2.4 Test procedure for method b) (mathematical). 55
8.2.5 Calculation and report . 56
8.3 Measurement of the pull strength of tamped or moulded connections . 56
8.3.1 General . 56
8.3.2 Principle . 56
8.3.3 Test equipment . 56
8.3.4 Test procedure . 59
8.3.5 Calculation and report . 59
9 Brush-holder dimensions and configuration . 59
9.1 General . 59
9.2 Dimensions of the inside of the brush-box . 59
9.2.1 Main dimensions . 59
9.2.2 Tolerances and clearances on brush-box t and a . 59
9.2.3 Dimensions and tolerances on brush-box chamfer . 60
9.3 Check of brush-box dimensions . 61
9.3.1 General . 61
9.3.2 Gauging of dimensions t and a . 61
9.3.3 Gauging of chamfers . 61
9.4 Serrations on fixing face of the brush-holder . 61
9.4.1 General . 61
9.4.2 Profile and dimensions of serrations . 61
9.4.3 Location of serrations . 62
9.5 Brush-holder mounting position . 62
Annex A (normative) Equivalent dimensions in inches . 63
Annex B (normative) Values of the principal dimensions of metal-graphite brushes . 66
Annex C (informative) Considerations relative to brush stability . 67
C.1 General . 67
C.2 Radial brush without top bevel angle operating in bidirectional rotation . 68
C.3 Radial brush with top bevel angle operating in the forward direction . 70
C.4 Radial brush with top bevel angle operating in the reverse direction . 71
C.5 Trailing type brushes . 72
C.6 Reaction type brush with top bevel angle . 74
Annex D (informative) Flexibles configuration . 77
Annex E (informative) Flexible location . 78
Annex F (informative) Recommended values of thickness for spade, flag and double
shoe terminals . 79
Annex G (informative) Technical questionnaire for the definition of a carbon brush . 80
Bibliography . 82

– 4 – IEC 60136:2024 © IEC 2024
Figure 1 – Examples of brush components . 11
Figure 2 – Chamfer height . 12
Figure 3 – Contact bevel angle α . 12
Figure 4 – Top bevel angle β . 13
Figure 5 – Pressure area width for commutator and for slip-ring . 13
Figure 6 – Depth of insertion . 14
Figure 7 – Residual material width . 14
Figure 8 – Safe length of a worn brush . 15
Figure 9 – Flexible dimensions l and d for different examples of brushes . 16
S S
Figure 10 – Definition of distance d for different types of brush connection . 17
P
Figure 11 – Brush-holder box chamfer height . 18
Figure 12 – Definition of serration location distance . 19
Figure 13 – Safe remaining length mark for different brush designs . 22
Figure 14 – Main dimensions for a wedge-edge brush. 23
Figure 15 – Preferred orientation for anisotropic grades depending on the application . 30
Figure 16 – Angle of chamfers . 30
Figure 17 – Split brush . 31
Figure 18 – Non-reversing chamfer height . 31
Figure 19 – Sharp edge when a contact bevel angle α is applied . 33
Figure 20 – Flat surface of edge when a top bevel angle β is applied . 33
Figure 21 – Flexible configuration illustration . 38
Figure 22 – Definition of shape and dimensions of axial spades terminals . 41
Figure 23 – Definition of shape and dimensions of flag terminals . 42
Figure 24 – Definition of shape and dimensions of double shoe terminals . 43
Figure 25 – Definition of shape and dimensions of tubular terminals . 44
Figure 26 – Definition of shape (example) and dimensions of formed spade terminal . 45
Figure 27 – Definition of shape (examples) and dimensions of two types of pin
terminals . 46
Figure 28 – Examples of testing device for the measurement of the connection

electrical resistance . 48
Figure 29 – Example of contact probe for flexible . 49
Figure 30 – Example of contact probe for brush . 49
Figure 31 – Measurement of connection resistance for a moulded or tamped
connection . 51
Figure 32 – Measurement of connection resistance for a riveted connection . 52
Figure 33 – Alternative method for the measurement of connection resistance in case
of 2 rivets. 53
Figure 34 – Connection with a metal top soldered or riveted to the block . 54
Figure 35 – Iterated determination of location P of Probe 2 . 55
Figure 36 – Test equipment for the measurement of the pull out force . 57
Figure 37 – Example of support device for brushes with inclined connection hole . 58
Figure 38 – Profile of serrations – cross-sectional view . 62
Figure C.1 – Illustration of rotational moments for a radial brush . 69

IEC 60136:2024 © IEC 2024 – 5 –
Figure C.2 – Illustration of forces applied on a radial brush with top bevel angle
operating in the forward rotation . 70
Figure C.3 – Illustration of forces applied on a radial brush with top bevel angle

operating in the reverse direction . 72
Figure C.4 – Illustration of forces applied on a trailing brush with a top bevel angle
operating in the forward direction . 73
Figure C.5 – Illustration of forces applied on a reaction brush . 75
Figure E.1 – Flexible location . 78
Figure G.1 – Main dimensions . 80
Figure G.2 – Brush operation . 81

Table 1 – Symbols for each unit system . 21
Table 2 – Standard dimensions of brush block . 24
Table 3 – Tolerances on t, a and r . 25
Table 4 – Recommended combination of t, a and r. 27
Table 5 – Dimension of chamfer height c . 31
Table 6 – Recommended values of non-reversing chamfer height . 32
Table 7 – Preferred values for contact bevel angle α and top bevel angle β . 33
Table 8 – Typical combination values for contact bevel angle α and top bevel angle β . 34
Table 9 – Recommended minimum values of pressure area width w . 35
p
Table 10 – Maximum values of depth of insertion q . 35
i
Table 11 – Example of maximum values of q for an EG grade . 36
i
Table 12 – Minimum width of residual material . 37
Table 13 – Recommended nominal area for flexibles and their corresponding maximum
diameter . 39
Table 14 – Standard lengths of flexibles l and tolerances . 40
S
Table 15 – Standard values of spades terminals dimensions . 42
Table 16 – Standard values of flag terminals dimensions . 43
Table 17 – Standard values of double shoe terminals dimensions . 44
Table 18 – Standard values of tubular terminals dimensions . 45
Table 19 – Standard values of formed spade terminals dimensions and tolerances . 46
Table 20 – Minimum values of current capacity for terminals . 47
Table 21 – Tolerances on brush box dimensions and clearances . 60
Table 22 – Maximum value of the brush-box chamfer height c . 60
H
Table A.1 – Standard dimensions and tolerances on brush dimensions t ⨯ a ⨯ r in inch
system . 63
Table A.2 – Nominal and maximum dimensions of chamfer height c to be used in inch
system . 64
Table A.3 – Recommended minimum value of w to be used in inch system . 64
p
Table A.4 – Maximum values of depth of insertion q . 64
i
Table A.5 – Recommended nominal area for flexibles (shunts) and their corresponding
maximum diameter. 65
Table A.6 – Standard lengths of flexibles l and tolerances . 65
S
Table B.1 – t ⨯ a ⨯ r tolerances and clearance for metal graphite grades . 66

– 6 – IEC 60136:2024 © IEC 2024
Table C.1 – Overview of the different mechanical configurations (bevel angles) in
operation . 67
Table D.1 – Configuration of flexibles . 77
Table F.1 – Recommended thickness for spade, flag and double shoe terminals
corresponding to screws diameter . 79
Table G.1 – Elements to be included in a form . 80

IEC 60136:2024 © IEC 2024 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIMENSIONS, MARKING AND TESTING OF CARBON BRUSHES AND
DIMENSIONS OF BRUSH-HOLDERS FOR ELECTRICAL MACHINERY

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60136 has been prepared by IEC technical committee TC 2: Rotating machinery. It is an
International Standard.
This third edition cancels and replaces the second edition published in 1986 and
Amendment 1:1995. This edition constitutes a technical revision.

– 8 – IEC 60136:2024 © IEC 2024
This edition includes the following significant technical changes with respect to the previous
edition:
Title: modified.
Clause or Previous
Change
subclause clause
1 I-1 Clarification and extension of the scope.
2 None New clause introduced.
3 None New clause introduced.
4 I-4 and II-7.5 Addition of units and extension of marking.
5.1 I-2 Addition of cylindrical and wedge-shape brushes.
5.2 I-3 Distinction of dimensions between t, a and r.
Revision of the chamfer dimension table and addition of
6.1 II-7.1
non-reversing chamfer.
6.2 II-7.2 Revision of angles dimensions and addition of typical
combination of angles.
6.4 II-7.4 Clarification of the definition of the depth of insertion and
modification of maximum values.
6.5 None New subclause introducing the concept of residual
material width.
7.1.2 II-8.7 Change of definition of flexibles area and diameter.
7.1.4 None Addition of flexible protection.
7.2 II-8.1 to II-8.5 Clarification. Addition of other types of terminals.
8 Annex C Clarification of the method of measurement of electrical
resistance and addition of graphical method.
9.2 and 9.3 Clause A.3 Brush-holder: Separation of Dimensions and Control of
brush box in two different subclauses.
Annex A None Compilation of tables with inches dimensions from the
previous edition.
Annex B None Addition of recommended dimensions for metal-graphite
grades.
Annex C None Explanation of stability of brushes (linked to 6.2).
Annex D II-8.7 Addition of examples of configuration of flexibles.
Annex E None Addition of recommended standardization of flexibles'
location
Annex F Annex D and II- Link between the thickness of terminals and the screw
8.8 diameter.
Annex G Annex B Simplification of the questionnaire, to include only
elements defined in this document.

The text of this International Standard is based on the following documents:
Draft Report on voting
2/2180/FDIS 2/2189/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
IEC 60136:2024 © IEC 2024 – 9 –
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 10 – IEC 60136:2024 © IEC 2024
DIMENSIONS, MARKING AND TESTING OF CARBON BRUSHES AND
DIMENSIONS OF BRUSH-HOLDERS FOR ELECTRICAL MACHINERY

1 Scope
This document applies primarily to brushes and brush-holders for cylindrical commutators and
slip rings for electrical rotating machines. Some clauses of this document may cover other
configurations, such as flat commutators or plain disks.
It defines the dimensions of brushes and their components, together with their tolerances:
– dimensions of brush block (t, a, r),
– angles α and β,
– chamfer,
– flexibles (shunts),
– standard terminals.
It also covers the conventional designation of principal dimensions, the marking of brushes and
the testing methods for the qualification of brushes after their manufacturing (except the brush
grade material, covered by IEC 60413).
And finally, it specifies dimensions of the brush-holders that are linked to brushes.
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.
IEC 60276:2018, Carbon brushes, brush holders, commutators and slip-rings – Definitions and
nomenclature
IEC 60560, Definitions and terminology of brush-holders for electrical machines
ISO 129-1, Technical product documentation (TPD) – Presentation of dimensions and
tolerances – Part 1: General principles
ISO 197-1:1983, Copper and copper alloys – Terms and definitions – Part 1: Materials
ISO 286-2:2010, Geometrical product specifications (GPS) – ISO code system for tolerances
on linear sizes – Part 2: Tables of standard tolerance classes and limit deviations for holes and
shafts
IEC 60136:2024 © IEC 2024 – 11 –
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60276:2018 and
IEC 60560, and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
component
element assembled onto the brush block and having a specific feature
Note 1 to entry: Figure 1 shows an example of a carbon brush designed for a DC machine, comprising the following
components: two flexibles, two terminals and one top plate.

Key
1 block
2 flexible
3 terminal
4 top plate
t tangential dimension of the brush
a axial dimension of the brush
r radial dimension of the brush
Figure 1 – Examples of brush components
3.1.2
chamfer height
c
smaller side of the isosceles rectangle triangle formed by the chamfer, as illustrated by Figure 2

– 12 – IEC 60136:2024 © IEC 2024

Figure 2 – Chamfer height
Note 1 to entry: c is expressed in millimetres (mm).
Note 2 to entry: In USA, c is also named depth of chamfer.
Note 3 to entry: The source of Figure 2 is IEC 60276:2018, item 147.
3.1.3
contact bevel angle
bottom bevel angle
α
angle between the centre line of the brush and the radial axis of the commutator or slip-ring, as
shown in Figure 3
Figure 3 – Contact bevel angle α
Note 1 to entry: α is expressed in degrees (°).
[SOURCE: IEC 60276:2018, item 106]
3.1.4
top bevel angle
β
angle between the centre line and the top surface of the carbon brush, as shown in Figure 4

IEC 60136:2024 © IEC 2024 – 13 –

Figure 4 – Top bevel angle β
Note 1 to entry: β is expressed in degrees (°).
Note 2 to entry: The source of Figure 4 is IEC 60276:2018, item 110.
3.1.5
pressure area width
w
p
width of the area on the top of the brush where the pressure system applies, as shown in
Figure 5
a) Commutator b) Slip-ring
Figure 5 – Pressure area width for commutator and for slip-ring
Note 1 to entry: w is expressed in millimetres (mm).
p
3.1.6
depth of insertion
q
i
distance between the extremity of flexible inside the brush and its insertion location onto the
top of the brush, along the flexible direction axis, as illustrated by Figure 6

– 14 – IEC 60136:2024 © IEC 2024

a) Radial brush b) Inclined brush c) Bevelled edge brush

Figure 6 – Depth of insertion
Note 1 to entry: q is expressed in millimetres (mm).
i
3.1.7
residual material width
w
i
width of the residual material adjacent to the flexible (see Figure 7), defined by the distance
between:
– the closest side of the brush block, and
– the periphery of the hole drilled for the insertion of the flexible

Key
1 brush
2 flexible
3 hole (for the flexible insertion)
Figure 7 – Residual material width
Note 1 to entry: w is expressed in millimetres (mm).
i
3.1.8
safe length of a worn brush
r
m
distance between two planes perpendicular to the centre line, passing over the extremities of:
– the contact surface at its minimum safe wear limit, and
– the elements of brush or parts of elements, which take part in the pressure application

IEC 60136:2024 © IEC 2024 – 15 –
Note 1 to entry: Figure 8 illustrates the definition of r for two examples.
m
a) Radial brush (α = 0 / β = 0) b) Inclined brush with a bevelled top and a top plate (α ≠ 0 /
β ≠ 0)
Key
1 worn brush
2 initial brush
3 rotating surface
r initial radial dimension
r safe length of the worn brush
m
NOTE Dash lines represent the worn part of the brush.
Figure 8 – Safe length of a worn brush
Note 2 to entry: r is expressed in millimetres (mm).
m
3.1.9
length of flexible
l
S
distance of the flexible between the brush-flexible connection (onto the brush top) and the screw
connection axis of the terminal, as illustrated by Figure 9
Note 1 to entry: l is expressed in millimetres (mm).
S
Note 2 to entry: When there is no terminal, the screw connection axis in the definition above is naturally replaced
by the free extremity of the flexible.
3.1.10
distance for the application of the flexible probe
d
S
distance, along the flexible direction axis, from a location S onto the flexible to the brush-flexible
connection (location O), as shown in Figure 9

– 16 – IEC 60136:2024 © IEC 2024

Key
O brush-flexible connection location on the top of the brush
S location onto the flexible
d distance for the application of the flexible probe
S
l length of the flexible
S
Figure 9 – Flexible dimensions l and d for different examples of brushes
S S
Note 1 to entry: d is expressed in millimetres (mm).
S
3.1.11
distance for application of the block probe
d
P
distance from a point P of a side of the block to a point P of the same side, which is the closest
to the outside of the connection mean, as shown in Figure 10

IEC 60136:2024 © IEC 2024 – 17 –

a) Tamped or moulded connection – b) Tamped or moulded connection – lateral
on the brush top
c) Riveted connection d) Connection by a riveted or soldered metal plate

Key
P location onto the side of the brush block
P location onto the same side of the brush block as P and closed to the brush-flexible connection
d distance for the application of the brush block probe
P
Figure 10 – Definition of distance d for different types of brush connection
P
Note 1 to entry: For any type of brush, the axis passing through both points P and P is parallel to its centre line.
The side of the block is chosen so that the distance from the axis (P;P ) and the centre line is minimum.
Note 2 to entry: d is expressed in millimetres (mm).
P
3.1.12
electrical resistance of the brush-flexible connection
R
f
electrical resistance measured between a point S onto the flexible (see Figure 9) and a point P
onto the brush body (see Figure 10)
Note 1 to entry: R is expressed in milliohms (mΩ).
f
– 18 – IEC 60136:2024 © IEC 2024
3.1.13
pull-out force of the brush-flexible connection
F
f
force required to pull out the fl
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