ISO 1081:2013

INTERNATIONAL ISO
STANDARD 1081
NORME
Third edition
Troisième édition
INTERNATIONALE 2013-12-01
Belt drives — V-belts and V-ribbed
belts, and corresponding grooved
pulleys — Vocabulary
Transmissions par courroies —
Courroies trapézoïdales et striées, et
poulies à gorges — Vocabulaire
Reference number
Numéro de référence
©
ISO 2013
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2013
The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, in-
struction booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for
such reproduction are: that no modifications are made to the terms and definitions; that such reproduction is not permitted for
dictionaries or similar publications offered for sale; and that this International Standard is referenced as the source document.
With the sole exceptions noted above, no other part of this publication may be reproduced or utilized otherwise in any form or
by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior writ-
ten permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of the
requester.
La reproduction des termes et des définitions contenus dans la présente Norme internationale est autorisée dans les manuels
d’enseignement, les modes d’emploi, les publications et revues techniques destinés exclusivement à l’enseignement ou à la mise
en application. Les conditions d’une telle reproduction sont les suivantes: aucune modification n’est apportée aux termes et
définitions; la reproduction n’est pas autorisée dans des dictionnaires ou publications similaires destinés à la vente; la présente
Norme internationale est citée comme document source.
À la seule exception mentionnée ci-dessus, aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque
forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur l’internet ou sur un
Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à l’adresse ci-après ou au
comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland/Publié en Suisse
ii © ISO 2013 – All rights reserved/Tous droits réservés

Contents Page
Foreword .iv
0 Scope . 1
1 Terms and definitions relating to V-belts and grooved pulleys . 1
1.1 General terms and definitions . 1
1.2 Terms and definitions relating to the system based on data widths . 5
1.3 Terms and definitions relating to the system based on effective width . 7
2 Terms and definitions related to V-belts and ribbed pulleys . 9
2.1 General terms and definitions . 9
3 Terms and definitions relating to tension .14
4 Terms and definitions relating to modulus .14
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 41, Pulleys and belts (including veebelts), SC 1,
Veebelts and grooved pulleys.
This third edition cancels and replaces the second edition (ISO 1081:1995), which has been technically revised.
iv © ISO 2013 – All rights reserved/Tous droits réservés

INTERNATIONAL STANDARD ISO 1081:2013(E/F)
Belt drives — V-belts and V-ribbed belts, and
corresponding grooved pulleys — Vocabulary
0 Scope
This International Standard specifies the terms and definitions, in English and French, relating to
aromatic natural raw materials.
This International Standard defines terms relating to V-belt drives, V-belts, hexagonal belts, joined
V-belts and the corresponding V-grooved pulleys, V-ribbed belt drives, V-ribbed belts and V-ribbed
pulleys, as well as the corresponding symbols.
The general definitions are valid irrespective of the system describing the pulleys.
The dimensions of pulley grooves can be defined either on the basis of the datum width or on the basis
of the effective width. As a result, two systems for the definition and description of the dimensions of
pulleys and belts have been developed. The two systems are independent of each other.
1 Terms and definitions relating to V-belts and grooved pulleys
1.1 General terms and definitions
1.1.1 Belts
1.1.1.1
V-belt
belt, the cross-section of which is shaped roughly like a regular trapezium
Note 1 to entry: On a cross-section of a straight-sided belt, the trapezium is outlined by the base, sides and
top of the belt.
Note 2 to entry: The intersection of the extended profiles of the base, side and top is considered when edges are
cut short or rounded.
Note 3 to entry: See Figure 1.
1.1.1.1.1
hexagonal belt
special belt with hexagonal cross-section consisting of two equal isosceles trapezia joined at their wider base
1.1.1.1.2
joined V-belt
two or more equal trapezoidal V-belts placed side by side in a definite distance and joined by a covering band
Figure 1 — V-belts
1.1.1.2
pitch line
any circumferential line in the belt which keeps the same length when the belt is bent perpendicularly
to its base
Note 1 to entry: See Figure 2.
Key
1 pitch line
Figure 2 — Pitch line
1.1.1.3
pitch zone
geometrical zone containing all of the pitch lines
Note 1 to entry: See Figure 3.
2 © ISO 2013 – All rights reserved/Tous droits réservés

Key
1 pitch zone
Figure 3 — Pitch zone
1.1.1.4
pitch width
w
p
width of the belt at its pitch zone (neutral zone)
Note 1 to entry: The width remains unchanged when the belt is bent perpendicularly to its base.
Note 2 to entry: See Figure 4.
1.1.1.5
top width
w
larger width of the trapezium outlined on a cross-section
Note 1 to entry: See Figure 4.
1.1.1.6
height
T
height of the trapezium outlined on a cross-section
Note 1 to entry: See Figure 4.
1.1.1.7
relative height
non-dimensional characteristic calculated as the ratio of height to pitch width (Tw )
p
Note 1 to entry: The approximate relative height of the four types of V-belt is as follows:

—  narrow V-belt: 0,9;
—  classical V-belt: 0,7;
—  half wide V-belt: 0,5;
—  wide V-belt: 0,3.
Figure 4 — Pitch width, top width, height
1.1.2 Pulleys
1.1.2.1
V-grooved pulley
pulley with one or more grooves obtained by rotation of a profile in the shape of a truncated or non-
truncated symmetrical V around the pulley axis
Note 1 to entry: A round groove bottom is acceptable. In most cases, all the grooves of a pulley have identical profiles.
1.1.2.2
angle of pulley groove
α
angle included by the sides of the groove cross-section
Note 1 to entry: For any given profile, the pulley groove angle may have several different values depending upon
the pulley diameter.
Note 2 to entry: See Figure 5.
Figure 5 — Angle of pulley groove
1.1.2.3
pitch width of pulley groove
w
p
width of the pulley groove which has the same dimension as the pitch width of the belt used with this pulley
4 © ISO 2013 – All rights reserved/Tous droits réservés

1.1.2.4
pitch diameter
d
p
diameter of the pulley at the pitch width of pulley groove
1.1.2.5
pitch circumference
C
p
circumference of a circle with a diameter equal to the pitch diameter
1.1.3 Drives
1.1.3.1
V-belt drive
drive which consists of one or more V-belts mounted on grooved pulleys
Note 1 to entry: The profiles of the belts and of the pulley grooves are such that the belts come into contact only
with the sides of the pulley grooves and not with the bottom of the grooves.
1.1.3.2
speed ratio
R
ratio of the angular velocities of the pulleys, as calculated from the ratio of the pitch diameters of the
pulleys, making no allowance for slip and creep
1.2 Terms and definitions relating to the system based on data widths
1.2.1 Pulleys
1.2.1.1
datum width
w
d
groove width characterizing the groove profile
Note 1 to entry: It is a defined value not subject to tolerance and is usually located at the level of the pitch zone of
the V-belt for which the pulley groove is preferably intended. It should coincide with the pitch width of that V-belt
within reasonable tolerances.
Note 2 to entry: The datum width of a pulley groove was previously designated as pitch width (l ). However, the
p
datum width is equal to the pitch width only when the pitch zone on the V-belt is located at the level of the datum
width of the pulley groove.
Note 3 to entry: If different angles of pulley groove (1.1.2.2) are required, the groove flanks shall be assumed to
hinge round both ends of the datum width.
Note 4 to entry: See Figure 6.
Figure 6 — Datum width
1.2.1.2
datum diameter
d
d
diameter of the pulley at the datum width of the pulley groove
Note 1 to entry: See Figure 7.
Figure 7 — Datum diameter
1.2.1.3
datum circumference
C
d
circumference of a circle with a diameter equal to the datum diameter
6 © ISO 2013 – All rights reserved/Tous droits réservés

1.2.1.4
datum line differential
b
d
radial displacement between the levels of the pitch width and the datum width
Note 1 to entry: The datum line differential is a correction term used for calculating the speed ratio when the
datum line is given.
Note 2 to entry: The datum line differential is zero if the pitch zone of the V-belt and the level of the datum width
of the pulley are coincident.
Note 3 to entry: See Figure 8.
Figure 8 — Datum line differential
1.2.2 Belts
1.2.2.1
datum length
L
d
length of a line circumscribing a V-belt at the level of the datum diameter of the measuring pulleys whilst
the V-belt is at a specified tension
Note 1 to entry: The datum length was previously designated as pitch length, L .
p
Note 2 to entry: The recommended method for measuring the datum length of a V-belt includes the use of a
measuring fixture having two pulleys of the same datum diameter. The datum length is obtained by adding the
datum circumference of one pulley to twice the measured distance between the pulley centres.
1.3 Terms and definitions relating to the system based on effective width
1.3.1 Pulleys
1.3.1.1
effective width
w
e
groove width characterizing the groove profile
Note 1 to entry: It is a defined value not subject to tolerance and is usually located at the outermost extremities of
the straight side walls of the groove.
Note 2 to entry: For all belt-measuring pulleys and for most machined-type pulleys, it coincides with the actual
top width of the groove within reasonable tolerances.
Note 3 to entry: If different angles of pulley groove (1.1.2.2) are required, the groove flanks shall be assumed to
hinge round both ends of the effective width.
Note 4 to entry: See Figure 9.
Figure 9 — Effective width
1.3.1.2
effective diameter
d
e
diameter of the pulley at the effective width of the pulley groove
Note 1 to entry: See Fig
...

INTERNATIONAL ISO
STANDARD 1081
NORME
Third edition
Troisième édition
INTERNATIONALE 2013-12-01
Belt drives — V-belts and V-ribbed
belts, and corresponding grooved
pulleys — Vocabulary
Transmissions par courroies —
Courroies trapézoïdales et striées, et
poulies à gorges — Vocabulaire
Reference number
Numéro de référence
©
ISO 2013
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2013
The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, in-
struction booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for
such reproduction are: that no modifications are made to the terms and definitions; that such reproduction is not permitted for
dictionaries or similar publications offered for sale; and that this International Standard is referenced as the source document.
With the sole exceptions noted above, no other part of this publication may be reproduced or utilized otherwise in any form or
by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior writ-
ten permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of the
requester.
La reproduction des termes et des définitions contenus dans la présente Norme internationale est autorisée dans les manuels
d’enseignement, les modes d’emploi, les publications et revues techniques destinés exclusivement à l’enseignement ou à la mise
en application. Les conditions d’une telle reproduction sont les suivantes: aucune modification n’est apportée aux termes et
définitions; la reproduction n’est pas autorisée dans des dictionnaires ou publications similaires destinés à la vente; la présente
Norme internationale est citée comme document source.
À la seule exception mentionnée ci-dessus, aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque
forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur l’internet ou sur un
Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à l’adresse ci-après ou au
comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland/Publié en Suisse
ii © ISO 2013 – All rights reserved/Tous droits réservés

Contents Page
Foreword .iv
0 Scope . 1
1 Terms and definitions relating to V-belts and grooved pulleys . 1
1.1 General terms and definitions . 1
1.2 Terms and definitions relating to the system based on data widths . 5
1.3 Terms and definitions relating to the system based on effective width . 7
2 Terms and definitions related to V-belts and ribbed pulleys . 9
2.1 General terms and definitions . 9
3 Terms and definitions relating to tension .14
4 Terms and definitions relating to modulus .14
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 41, Pulleys and belts (including veebelts), SC 1,
Veebelts and grooved pulleys.
This third edition cancels and replaces the second edition (ISO 1081:1995), which has been technically revised.
iv © ISO 2013 – All rights reserved/Tous droits réservés

INTERNATIONAL STANDARD ISO 1081:2013(E/F)
Belt drives — V-belts and V-ribbed belts, and
corresponding grooved pulleys — Vocabulary
0 Scope
This International Standard specifies the terms and definitions, in English and French, relating to
aromatic natural raw materials.
This International Standard defines terms relating to V-belt drives, V-belts, hexagonal belts, joined
V-belts and the corresponding V-grooved pulleys, V-ribbed belt drives, V-ribbed belts and V-ribbed
pulleys, as well as the corresponding symbols.
The general definitions are valid irrespective of the system describing the pulleys.
The dimensions of pulley grooves can be defined either on the basis of the datum width or on the basis
of the effective width. As a result, two systems for the definition and description of the dimensions of
pulleys and belts have been developed. The two systems are independent of each other.
1 Terms and definitions relating to V-belts and grooved pulleys
1.1 General terms and definitions
1.1.1 Belts
1.1.1.1
V-belt
belt, the cross-section of which is shaped roughly like a regular trapezium
Note 1 to entry: On a cross-section of a straight-sided belt, the trapezium is outlined by the base, sides and
top of the belt.
Note 2 to entry: The intersection of the extended profiles of the base, side and top is considered when edges are
cut short or rounded.
Note 3 to entry: See Figure 1.
1.1.1.1.1
hexagonal belt
special belt with hexagonal cross-section consisting of two equal isosceles trapezia joined at their wider base
1.1.1.1.2
joined V-belt
two or more equal trapezoidal V-belts placed side by side in a definite distance and joined by a covering band
Figure 1 — V-belts
1.1.1.2
pitch line
any circumferential line in the belt which keeps the same length when the belt is bent perpendicularly
to its base
Note 1 to entry: See Figure 2.
Key
1 pitch line
Figure 2 — Pitch line
1.1.1.3
pitch zone
geometrical zone containing all of the pitch lines
Note 1 to entry: See Figure 3.
2 © ISO 2013 – All rights reserved/Tous droits réservés

Key
1 pitch zone
Figure 3 — Pitch zone
1.1.1.4
pitch width
w
p
width of the belt at its pitch zone (neutral zone)
Note 1 to entry: The width remains unchanged when the belt is bent perpendicularly to its base.
Note 2 to entry: See Figure 4.
1.1.1.5
top width
w
larger width of the trapezium outlined on a cross-section
Note 1 to entry: See Figure 4.
1.1.1.6
height
T
height of the trapezium outlined on a cross-section
Note 1 to entry: See Figure 4.
1.1.1.7
relative height
non-dimensional characteristic calculated as the ratio of height to pitch width (Tw )
p
Note 1 to entry: The approximate relative height of the four types of V-belt is as follows:

—  narrow V-belt: 0,9;
—  classical V-belt: 0,7;
—  half wide V-belt: 0,5;
—  wide V-belt: 0,3.
Figure 4 — Pitch width, top width, height
1.1.2 Pulleys
1.1.2.1
V-grooved pulley
pulley with one or more grooves obtained by rotation of a profile in the shape of a truncated or non-
truncated symmetrical V around the pulley axis
Note 1 to entry: A round groove bottom is acceptable. In most cases, all the grooves of a pulley have identical profiles.
1.1.2.2
angle of pulley groove
α
angle included by the sides of the groove cross-section
Note 1 to entry: For any given profile, the pulley groove angle may have several different values depending upon
the pulley diameter.
Note 2 to entry: See Figure 5.
Figure 5 — Angle of pulley groove
1.1.2.3
pitch width of pulley groove
w
p
width of the pulley groove which has the same dimension as the pitch width of the belt used with this pulley
4 © ISO 2013 – All rights reserved/Tous droits réservés

1.1.2.4
pitch diameter
d
p
diameter of the pulley at the pitch width of pulley groove
1.1.2.5
pitch circumference
C
p
circumference of a circle with a diameter equal to the pitch diameter
1.1.3 Drives
1.1.3.1
V-belt drive
drive which consists of one or more V-belts mounted on grooved pulleys
Note 1 to entry: The profiles of the belts and of the pulley grooves are such that the belts come into contact only
with the sides of the pulley grooves and not with the bottom of the grooves.
1.1.3.2
speed ratio
R
ratio of the angular velocities of the pulleys, as calculated from the ratio of the pitch diameters of the
pulleys, making no allowance for slip and creep
1.2 Terms and definitions relating to the system based on data widths
1.2.1 Pulleys
1.2.1.1
datum width
w
d
groove width characterizing the groove profile
Note 1 to entry: It is a defined value not subject to tolerance and is usually located at the level of the pitch zone of
the V-belt for which the pulley groove is preferably intended. It should coincide with the pitch width of that V-belt
within reasonable tolerances.
Note 2 to entry: The datum width of a pulley groove was previously designated as pitch width (l ). However, the
p
datum width is equal to the pitch width only when the pitch zone on the V-belt is located at the level of the datum
width of the pulley groove.
Note 3 to entry: If different angles of pulley groove (1.1.2.2) are required, the groove flanks shall be assumed to
hinge round both ends of the datum width.
Note 4 to entry: See Figure 6.
Figure 6 — Datum width
1.2.1.2
datum diameter
d
d
diameter of the pulley at the datum width of the pulley groove
Note 1 to entry: See Figure 7.
Figure 7 — Datum diameter
1.2.1.3
datum circumference
C
d
circumference of a circle with a diameter equal to the datum diameter
6 © ISO 2013 – All rights reserved/Tous droits réservés

1.2.1.4
datum line differential
b
d
radial displacement between the levels of the pitch width and the datum width
Note 1 to entry: The datum line differential is a correction term used for calculating the speed ratio when the
datum line is given.
Note 2 to entry: The datum line differential is zero if the pitch zone of the V-belt and the level of the datum width
of the pulley are coincident.
Note 3 to entry: See Figure 8.
Figure 8 — Datum line differential
1.2.2 Belts
1.2.2.1
datum length
L
d
length of a line circumscribing a V-belt at the level of the datum diameter of the measuring pulleys whilst
the V-belt is at a specified tension
Note 1 to entry: The datum length was previously designated as pitch length, L .
p
Note 2 to entry: The recommended method for measuring the datum length of a V-belt includes the use of a
measuring fixture having two pulleys of the same datum diameter. The datum length is obtained by adding the
datum circumference of one pulley to twice the measured distance between the pulley centres.
1.3 Terms and definitions relating to the system based on effective width
1.3.1 Pulleys
1.3.1.1
effective width
w
e
groove width characterizing the groove profile
Note 1 to entry: It is a defined value not subject to tolerance and is usually located at the outermost extremities of
the straight side walls of the groove.
Note 2 to entry: For all belt-measuring pulleys and for most machined-type pulleys, it coincides with the actual
top width of the groove within reasonable tolerances.
Note 3 to entry: If different angles of pulley groove (1.1.2.2) are required, the groove flanks shall be assumed to
hinge round both ends of the effective width.
Note 4 to entry: See Figure 9.
Figure 9 — Effective width
1.3.1.2
effective diameter
d
e
diameter of the pulley at the effective width of the pulley groove
Note 1 to entry: See Fig
...