ISO 17396:2014

Synchronous belt drives — Metric pitch, trapezoidal profile systems T and AT, belts and pulleys

ISO 17396:2014 specifies the principal characteristics of synchronous endless and open belts and pulleys of the profile systems T and AT for use in synchronous belt drives for mechanical power transmission and where positive indexing or synchronization can be required. The principal belt and pulley characteristics include nominal belt tooth dimensions, belt tooth pitch spacing, belt length and width dimensions, belt length measurement specifications, pulley groove dimensions and tolerances, pulley diameter and width dimensions and tolerances, and pulley quality specification.

Transmissions synchrones par courroies — Pas métrique, poulies et courroies dentées à dents trapézoïdales de profil T ou AT

General Information

• Status: Withdrawn
• Publication Date: 15-Jan-2014
• Withdrawal Date: 15-Jan-2014
• ICS: 21.220.10 - Belt drives and their components
• Technical Committee: ISO/TC 41/SC 4 - Synchronous belt drives
• Drafting Committee: ISO/TC 41/SC 4 - Synchronous belt drives
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 24-Nov-2017

Relations

• Revised: ISO 17396:2017 - Synchronous belt drives — Metric pitch — Tooth profiles T and AT endless and open ended belts and pulleys
• Effective Date: 23-Jan-2016

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17396
First edition
2014-01-15
Synchronous belt drives — Metric
pitch, trapezoidal profile systems T
and AT, belts and pulleys
Transmissions synchrones par courroies — Pas métrique, poulies et
courroies dentées à dents trapézoïdales de profil T ou AT
Reference number
ISO 17396:2014(E)
©
ISO 2014

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ISO 17396:2014(E)

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© ISO 2014
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ISO 17396:2014(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Belt profile systems . 1
4 Belt nomenclature . 2
5 Pulley profile systems . 2
6 Pulley nomenclature . 2
7 Belt profile systems T and AT . 3
7.1 Belt profile systems T and AT — General . 3
7.2 Profile system T — Belt tooth dimensions and tolerances . 3
7.3 Profile system AT — Belt tooth dimensions and tolerances . 4
8 Belt widths and tolerances. 4
9 Pitch length measurement . 5
9.1 Endless belts manufactured in circular moulds . 5
9.2 For very long endless belts and open belts . 6
9.3 Total measuring forces . 7
9.4 Procedures . 7
9.5 Belt length tolerances . 8
10 Pulleys . 9
10.1 General profile system T . 9
10.2 General profile system AT.12
Annex A (normative) Pulley tolerances .15
Bibliography .18
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ISO 17396:2014(E)

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 (see 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 (see 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),
Subcommittee SC 4, Synchronous belt drives.
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INTERNATIONAL STANDARD ISO 17396:2014(E)
Synchronous belt drives — Metric pitch, trapezoidal profile
systems T and AT, belts and pulleys
1 Scope
This International Standard specifies the principal characteristics of synchronous endless and open
1)
belts and pulleys of the profile systems T and AT for use in synchronous belt drives for mechanical
power transmission and where positive indexing or synchronization can be required.
The principal belt and pulley characteristics include
a) nominal belt tooth dimensions,
b) belt tooth pitch spacing,
c) belt length and width dimensions,
d) belt length measurement specifications,
e) pulley groove dimensions and tolerances,
f) pulley diameter and width dimensions and tolerances, and
g) pulley quality specification.
The belts of the profile systems T and AT are made of polyurethane with high-tension fine steel cord
tension members in most cases. As far as certain forces are given in this International Standard, these
values are only valid for this kinds of belt. For polyurethane belts with different tensile cords, i.e. aramid
or rubber belts reinforced with glass fibre, the values can be different. It is intended that the user and
the manufacturer agree about suitable values. Open belts made of thermoplastic polyurethane can be
spliced to work as endless belts in conveyor applications. In this case, the tolerances are not valid for the
splicing area of the endless spliced belt.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 254, Belt drives — Pulleys — Quality, finish and balance
3 Belt profile systems
Eight belt profiles for synchronous drives are standardized.
Profile system T: Profile system AT:
— profile T2,5 —  profile AT3
— profile T5  —  profile AT5
— profile T10 —  profile AT10
1) Synchronous belt drives have been known by various titles in the past: for example, timing belt drives,
positive belt drives, gear belt drives.
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ISO 17396:2014(E)

— profile T20 —  profile AT20
4 Belt nomenclature
A belt is designated by a combination of numbers and letters as follows:
a) the width, in millimetres;
b) the profile system;
c) the pitch, in millimetres;
d) the belt pitch length, in millimetres (and add the number of teeth in brackets, if required);
e) double-sided belts are designated by adding D or D before the profile system letter: D if the tooth
G T G
position is opposite Gap; D if the tooth position is opposite Tooth;
T
f) open belts are designated by adding the letter “M” behind the length; for spliced belts, use the letter
“V.”
EXAMPLE 1 A metric synchronous belt of 10 mm pitch, profile system T, 50 mm wide, and 1 400 mm in pitch
length is designated as:
— for a single-sided belt: 50 - T10 - 1 400
— for a double-sided belt : 50 - D - T10 - 1 400 or 50 - D - T10 - 1 400
G T
EXAMPLE 2 A metric synchronous belt of 5 mm pitch, profile system AT, 25 mm wide, and 500 mm in pitch
length (number of teeth = 100) is designated as:
— for a single-sided belt: 25 - AT5 - 500 (100 t)
— for double-sided belt: 25 - D - AT5 - 500 (100 t) or 25 - D - AT5 - 500 (100 t)
G T
EXAMPLE 3 An open metric synchronous belt of 5 mm pitch, profile system AT, 25 mm wide, and 50000 mm in
pitch length is designated as:
    25 - AT5 - 50000 - M
5 Pulley profile systems
Eight pulley profiles for synchronous drives are standardized:
Profile system T: Profile system AT:
— profile T2,5 —  profile AT3
— profile T5  —  profile AT5
— profile T10 —  profile AT10
— profile T20 —  profile AT20
6 Pulley nomenclature
A pulley for a synchronous drive is identified by the number of grooves, the groove pitch and profile, and
the width. It is designated, as is the belt, by a combination of numbers and letters as follows:
a) the letter “P,” which indicates a pulley;
b) the number of grooves;
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ISO 17396:2014(E)

c) the profile system;
d) the groove pitch, in millimetres;
e) the width, in millimetres.
EXAMPLE A pulley for a metric toothed belt which has 20 mm pitch and 30 grooves with a nominal width of
50 mm is identified as follows.
— for T-profile system pulley: P30 - T20 - 50
— for AT-profile system pulley: P30 - AT20 - 50
7 Belt profile systems T and AT
7.1 Belt profile systems T and AT — General
Figure 1 — Belt dimensions for profile systems T and AT
7.2 Profile system T — Belt tooth dimensions and tolerances
The nominal belt tooth dimensions are the same for single-sided and double-sided belts; they are given
in Table 1 and shown in Figure 1.
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ISO 17396:2014(E)

Table 1 — Profile system T — Nominal tooth dimensions
Belt pro- Pitch Tooth angle Root width h h h r r
s d t a r
file P 2β ° S mm mm mm min ±0,1
b r
mm mm mm mm
T2,5 2,5 40 ± 2 1,50 ± 0,05 1,30 ± 0,15 1,90 0,70 ± 0,05 0,2 0,2
T5 5,0 40 ± 2 2,65 ± 0,05 2,20 ± 0,15 3,25 1,20 ± 0,05 0,4 0,4
T10 10,0 40 ± 2 5,30 ± 0,10 4,50 ± 0,30 6,80 2,50 ± 0,10 0,6 0,6
T20 20,0 40 ± 2 10,15 ± 0,15 8,00 ± 0,45 12,85 5,00 ± 0,15 0,8 0,8
NOTE The value of h can vary due to process-related adjustments of the manufacturer.
d
7.3 Profile system AT — Belt tooth dimensions and tolerances
The nominal belt tooth dimensions are the same for single-sided and double-sided belts; they are given
in Table 2 and shown in Figure 1.
Table 2 — Profile system AT — Nominal tooth dimensions
Belt profile Pitch Tooth Head width h h h r r
s d t a r
P angle S mm mm mm min ±0,1
b h
mm 2β ° mm mm mm
AT3 3,0 50 ± 2 1,50 ± 0,05 1,90 ± 0,15 n.a. 1,10 ± 0,05 0,3 0,1
AT5 5,0 50 ± 2 2,50 ± 0,05 2,70 ± 0,15 3,05 1,20 ± 0,05 0,4 0,6
a
AT10 10,0 50 ± 2 5,00 ± 0,10 4,50 ± 0,30 6,50 2,50 ± 0,10 0,6 1,2
(5,0)
a
AT20 20,0 50 ± 2 10,00 ± 0,15 8,00 ± 0,45 12,15 5,00 ± 0,15 1,6 2,5
(9,0)
NOTE The value of h can vary due to process-related adjustments of the manufacturer.
d
a
The thickness of the backside depends on the method of manufacturing.
8 Belt widths and tolerances
Belt widths and tolerances are given in Table 3.
Table 3 — Belt widths and width tolerances
Dimensions in millimetres
Belt profile Nominal belt width Tolerance
T2,5 - 4 6 10 ±0,3
T5 6 10 16 25 ±0,5
T10 16 25 32 50 ±0,5
T20 32 50 75 100 ±1,0
AT3 6 10 16 25 ±0,3
AT5 6 10 16 25 ±0,5
AT10 16 25 32 50 ±0,5
AT20 32 50 75 100 ±1,0
NOTE Tolerances for larger belt widths and closer tolerances to be confirmed between the user and the manufacturer.
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ISO 17396:2014(E)

9 Pitch length measurement
9.1 Endless belts manufactured in circular moulds
9.1.1 Measuring fixture (see Figure 2)
The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture
composed of the following elements.
9.1.1.1 Two pulleys of equal diameter, as specified in Table 4, of the proper profile shown in Table 7.
One pulley shall be free to rotate on a fixed-position shaft, while the other shall be free to rotate on a
moveable shaft to permit the centre distance to change.
9.1.1.2 Means of applying a total measuring force, to the moveable pulley, as given in Table 5.
9.1.1.3 Means of measuring the centre distance between the two pulleys with the necessary degree of
accuracy for centre distance measurement.
NOTE The number of pulley teeth specified in Table 4 determines the recommended sizes for measuring the
belt pitch length. Practicably, the other sizes of pulleys can be used provided they have the same number of teeth
and meet the dimensional requirements of Table 4.
Key
1 total measuring force
2 centre distance
Figure 2 — Fixture for measuring the pitch length for endless belts manufactured in circular
moulds
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ISO 17396:2014(E)

Table 4 — Belt length measuring pulleys
Dimensions in millimetres
Pitch Outside
Belt profile Number of grooves Radial runout Axial runout
a
circumference diameter
a a
FIM FIM
T2,5 20 50 15,42 0,013 0,025
−0,05
T5 20 100 30,99 0,013 0,025
−0,05
T10 20 200 61,80 0,013 0,025
−0,08
T20 20 400 124,47 0,013 0,050
−0,08
AT3 20 60 18,69 0,013 0,025
−0,05
AT5 20 100 30,61 0,013 0,025
−0,05
AT10 24 240 74,57 0,013 0,025
−0,08
AT20 25 500 156,33 0,013 0,050
−0,08
a
Full indicator movement.
9.2 For very long endless belts and open belts
9.2.1 Measuring fixt
...