IEC 60136:2024

Dimensions, marking and testing of carbon brushes and dimensions of brush-holders for electrical machinery

IEC 60136:2024 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). This third edition cancels and replaces the second edition published in 1986 and Amendment 1:1995. This edition constitutes a technical revision.
Please refer to the Foreword of the document for a comprehensive listing of the changes with respect to the previous edition.

Dimensions, marquages et essais des balais et dimensions des porte-balais pour machines électriques

IEC 60136:2024 s'applique principalement aux balais et aux porte-balais montés sur collecteurs cylindriques et bagues des machines électriques tournantes. Certains articles du présent document peuvent couvrir d'autres configurations, comme les collecteurs plats ou les disques lisses. Il définit les dimensions des balais et de leurs composants, ainsi que leurs tolérances:
- dimensions du bloc de balai (t, a, r);
- angles α et β;
- chanfrein;
- câbles (shunts);
- cosses normalisées.
Il couvre également la désignation conventionnelle des dimensions principales, le marquage des balais et les méthodes d'essai pour la qualification des balais après leur fabrication (à l'exception du matériau de la nuance des balais, couvert par l'IEC 60413). Cette troisième édition annule et remplace la deuxième édition parue en 1986 et l'Amendement 1:1995. Cette édition constitue une révision technique.
Veuillez vous référer à l'avant-propos du document pour une liste complète des modifications par rapport à l'édition précédente.

General Information

• Status: Published
• Publication Date: 07-May-2024
• ICS: 29.160.10 - Components for rotating machines
• Technical Committee: TC 2 - Rotating machinery
• Drafting Committee: MT 14 - TC 2/MT 14
• Current Stage: PPUB - Publication issued
• Start Date: 08-May-2024
• Completion Date: 17-May-2024

Overview

IEC 60136:2024 is the latest international standard published by the International Electrotechnical Commission (IEC) that establishes precise requirements for the dimensions, marking, and testing of carbon brushes and brush-holders used in electrical rotating machinery. This third edition supersedes the 1986 version and its 1995 amendment, reflecting a comprehensive technical revision to meet modern industry needs.

Primarily covering brushes and brush-holders for cylindrical commutators and slip rings, IEC 60136:2024 ensures standardized dimensions and tolerances for brush components, facilitating compatibility and interchangeability across manufacturers and equipment. The standard also addresses certain other configurations such as flat commutators and plain disks, underlining its relevance to a wide range of electrical machinery.

Key Topics

• Brush Dimensions and Tolerances
  The standard defines detailed principal dimensions such as brush block thickness (t), width (a), and radius (r), supported by precise tolerances. It specifies angles α (contact bevel) and β (top bevel), chamfers, and flexible connections (shunts) including their dimensions and positions.

• Marking Requirements
  IEC 60136:2024 outlines requirements for brush marking to ensure correct identification. Marking includes principal dimensions and additional information for traceability and quality control.

• Brush-Holders Dimensions
  The standard details the dimensions of brush-holders including the brush-box's inner dimensions, tolerances, chamfers, and serration profiles for brush mounting and stability.

• Testing Procedures
  It provides methods for physical testing of brushes after manufacturing including:

  • Electrical resistance measurements of brush-to-flexible connections
  • Mechanical pull strength tests of tamped or molded connections
    These tests verify the reliability and performance of brushes before deployment.

• Terminal Specifications
  IEC 60136 specifies the forms and sizes of brush terminals including axial spade, flag, double shoe, tubular, and soldered terminals along with their current capacity, ensuring reliable electrical connectivity.

Applications

IEC 60136:2024 is vital for manufacturers, designers, and users of electrical rotating machines such as:

• Motors and Generators with cylindrical commutators or slip rings
• Industrial machinery requiring precise brush and brush-holder components for optimal performance
• Renewable energy systems, electric traction, and automotive electrical drives where carbon brushes are used
• Maintenance and quality assurance processes to verify brush conformity and durability through standardized testing

Adoption of IEC 60136:2024 leads to enhanced operational reliability, reduced downtime due to brush failure, and streamlined inventory management by standardizing brush parts across the industry.

Related Standards

• IEC 60413: Covers the classification and properties of carbon brush materials complementing the dimensional and testing provisions of IEC 60136.
• IEC 60085: Pertains to insulation temperature ratings, relevant when selecting brushes for specific electrical environments.
• IEC 60947 Series: General standards for electrical switchgear where brush-holder components may be integrated.

Benefits of Compliance

• Ensures interchangeability and compatibility of brushes and brush-holders globally.
• Provides clear guidelines for manufacturing tolerances that reduce failures and improve equipment lifespan.
• Enhances quality control through defined testing methodologies post production.
• Supports the design of safe and efficient brush assemblies that maintain good electrical contact and minimize wear.

IEC 60136:2024 is an essential reference for any stakeholder involved in the design, production, and maintenance of electrical rotating machinery components involving carbon brushes and brush-holders, contributing to global harmonization in electromechanical equipment standards.

Standards Content (Sample)

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
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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

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

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

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIMENSIONS, MARKING AND TESTING OF CARBON BRUSHES AND
DIMENSIONS OF BRUSH-HOLDERS FOR ELECTRICAL MACHINERY

FOREWORD
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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.
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
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

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

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

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 flexible from the brush in the direction of the flexible axis
Note 1 to entry: F is expressed in newtons (N).
f
3.1.14
brush-holder box chamfer height
c
H
smaller side of the isosceles rectangle triangle formed by the chamfer of the brush-box
Note 1 to entry: By extension, the height of the brush box non-reversing chamfer c can be defined. Figure 11
HX
illustrates the definitions.
a) Chamfer b) Non-reversing chamfer

Key
1 brush
2 brush-box
c height of the brush box chamfer
H
c height of the brush box non-reversing chamfer
HX
Figure 11 – Brush-holder box chamfer height
Note 2 to entry: c is expressed in millimetres (mm).
H
3.1.15
serration location distance
d
H
distance from any tooth root of the serrated side of the brush-holder to the bottom of the brush
box, in vertical direction, as illustrated by Figure 12

Key
1 brush-holder box
2 serrated face of the fixation of the brush-holder
3 any tooth root of the serrated face
4 bottom of the brush box
5 brush centre line
d serration location distance
H
d mounting distance
M
e distance between the tip of the tooth and the axis of application of the mounting distance
H
Figure 12 – Definition of serration location distance
Note 1 to entry: d is an integer and is expressed in millimetres (mm).
H
Note 2 to entry: The profile and
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