ISO 13050:2014
(Main)Synchronous belt drives — Metric pitch, curvilinear profile systems G, H, R and S, belts and pulleys
Synchronous belt drives — Metric pitch, curvilinear profile systems G, H, R and S, belts and pulleys
ISO 13050:2014 specifies the principal characteristics of metric pitch curvilinear synchronous endless belts and pulleys in G, H, R, and S profile systems for use in synchronous belt drives (also known in the past as timing belt drives, positive belt drives, gear belt drives) for mechanical power transmission and where positive indexing or synchronization might be required. The principal belt and pulley characteristics include the following: nominal belt tooth dimensions; belt tooth pitch spacing; belt length and width dimensions and tolerances; belt length measurement specifications; pulley groove dimensions and tolerances; pulley diameter and width dimensions and tolerances; pulley quality specification.
Transmissions synchrones — Pas métrique, systèmes à denture curviligne G, H, R et S, courroies et poulies
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INTERNATIONAL ISO
STANDARD 13050
Second edition
2014-12-01
Corrected version
2016-04-01
Synchronous belt drives — Metric
pitch, curvilinear profile systems G, H,
R and S, belts and pulleys
Transmissions synchrones — Pas métrique, systèmes à denture
curviligne G, H, R et S, courroies et poulies
Reference number
ISO 13050:2014(E)
©
ISO 2014
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ISO 13050:2014(E)
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© ISO 2014, Published in Switzerland
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ii © ISO 2014 – All rights reserved
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ISO 13050:2014(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Synchronous belt drive system types . 2
4 Belt nomenclature . 3
5 Pulley nomenclature . 3
6 Profile system G . 4
6.1 Belt dimensions and tolerances . 4
6.1.1 Belt tooth dimensions . 4
6.1.2 Belt widths and tolerances . 5
6.1.3 Pitch length measurement . 5
6.2 Pulleys, profile system G . 7
6.2.1 General. 7
6.2.2 Generating tool rack . . 7
6.2.3 Pulley groove profile dimensions and tolerances . 9
6.2.4 Pulley outside diameters .10
6.2.5 Pulley width .12
7 Profile system H .13
7.1 Belt dimensions and tolerances .13
7.1.1 Belt tooth dimensions .13
7.1.2 Belt widths and tolerances .14
7.1.3 Pitch length measurement .15
7.1.4 Procedure .15
7.2 Pulleys, profile system H .17
7.2.1 General.17
7.2.2 Generating tool rack . .17
7.2.3 Pulley groove profile dimensions and tolerances .19
7.2.4 Pulley outside diameters .21
7.2.5 Pulley width .24
8 Profile system R .25
8.1 Belt dimensions and tolerances .25
8.1.1 Belt tooth dimensions .25
8.1.2 Belt widths and tolerances .26
8.1.3 Pitch length measurement .26
8.2 Pulleys, profile system R .29
8.2.1 General.29
8.2.2 Generating tool rack . .29
8.2.3 Pulley groove profile dimensions and tolerances .31
8.2.4 Pulley outside diameters .32
8.2.5 Pulley width .35
9 Profile system S .38
9.1 Belt dimensions and tolerances .38
9.1.1 Belt tooth dimensions .38
9.1.2 Belt widths and tolerances .39
9.1.3 Pitch length measurement .39
9.2 Pulleys, profile system S .41
9.2.1 General.41
9.2.2 Generating tool rack . .42
9.2.3 Pulley groove profile dimensions and tolerances .43
9.2.4 Pulley outside diameters .44
9.2.5 Pulley width .45
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ISO 13050:2014(E)
Annex A (normative) Belt pitch lengths and tolerances .47
Annex B (normative) Relationship between centre distance and belt pitch length .49
Annex C (normative) Pulley tolerances .50
Annex D (normative) Flange dimensions .53
Bibliography .54
iv © ISO 2014 – All rights reserved
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ISO 13050:2014(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, Belts and pulleys (including veebelts),
Subcommittee SC 4, Synchronous belt drives.
This second edition cancels and replaces the first edition (ISO 13050:1999), which has been technically
revised.
This corrected version of ISO 13050:2014 incorporates the following corrections: in Formulas (1) and
(2), “Ao” has been added before the first square bracket in each equation.
© ISO 2014 – All rights reserved v
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INTERNATIONAL STANDARD ISO 13050:2014(E)
Synchronous belt drives — Metric pitch, curvilinear profile
systems G, H, R and S, belts and pulleys
1 Scope
This International Standard specifies the principal characteristics of metric pitch curvilinear
synchronous endless belts and pulleys in G, H, R, and S profile systems for use in synchronous belt
drives (also known in the past as timing belt drives, positive belt drives, gear belt drives) for mechanical
power transmission and where positive indexing or synchronization might be required.
The principal belt and pulley characteristics include the following:
a) nominal belt tooth dimensions;
b) belt tooth pitch spacing;
c) belt length and width dimensions and tolerances;
d) belt length measurement specifications;
e) pulley groove dimensions and tolerances;
f) pulley diameter and width dimensions and tolerances;
g) pulley quality specification.
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
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ISO 13050:2014(E)
3 Synchronous belt drive system types
Four profile systems and 14 profiles for curvilinear synchronous drives are standardized.
Profile system G Profile system R
Profile G8M Profile R3M
(Tooth/groove pitch 8mm) (Tooth/groove pitch 3mm)
Profile G14M Profile R5M
(Tooth/groove pitch 14mm) (Tooth/groove pitch 5mm)
Profile R8M
(Tooth/groove pitch 8mm)
Profile R14M
(Tooth/groove pitch 14mm)
Profile R20M
(Tooth/groove pitch 20mm)
Profile system H Profile system S
Profile H3M Profile S8M
(Tooth/groove pitch 3mm) (Tooth/groove pitch 8mm)
Profile H5M Profile S14M
(Tooth/groove pitch 5mm) (Tooth/groove pitch 14mm)
Profile H8M
(Tooth/groove pitch 8mm)
Profile H14M
(Tooth/groove pitch 14mm)
Profile H20M
(Tooth/groove pitch 20mm)
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ISO 13050:2014(E)
4 Belt nomenclature
A belt is identified as follows:
a) the belt length or pitch length in millimetres, e.g. 1 400 mm;
b) the profile system, e.g. “G”,“H”, “R”, or “S”;
c) the pitch or tooth pitch in millimetres, e.g. 14 mm;
d) the width or belt width in millimetres, e.g. 40 mm (for profile system S, the width in millimetres × 10);
e) double-sided belts are designated by adding the letter “D” before the designation of the profile system.
EXAMPLE A synchronous belt in the above profile systems of 1 400 mm length, 14 mm pitch, and 40 mm
wide is identified as follows:
Profile system G Profile system R
1400-G14M-40 1400-R14M-40
1400-DG14M-40 1400-DR14M-40
Profile system H Profile system S
1400-H14M-40 1400-S14M-400
1400-DH14M-40 1400-DS14M-400
5 Pulley nomenclature
A pulley is identified as follows:
a) the letter “P” indicates a pulley;
b) the number of grooves, e.g. 30;
c) the profile system, e.g. “G“, “H”, “R”, or “S”;
d) the pitch or groove pitch in millimetres, e.g. 14 mm;
e) the width or belt width in millimetres, e.g. 40 mm (for profile system S, the width in millimetres × 10).
EXAMPLE A pulley in the above profile systems of 30 grooves, 14 mm pitch, and 40 mm wide is identified as
follows:
Profile system G Profile system R
P30-G14M-40 P30-R14M-40
Profile system H Profile system S
P30-H14M-40 P30-S14M-400
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ISO 13050:2014(E)
6 Profile system G
6.1 Belt dimensions and tolerances
6.1.1 Belt tooth dimensions
The nominal belt tooth dimensions are given in Table 1 and shown in Figure 1.
Table 1 — Nominal tooth dimensions
Dimensions in millimetres
a
Profile Belt pitch b h R1 Ao a xo L1
g g
G8M 8 5,200 3,43 0,74 2,29 0,80 0,379 1,378
G14M 14 9,100 6,00 1,30 4,00 1,40 0,661 2,422
a
a is the belt design pitch differential.
R1
a
b
g xo
h
g
Y
Ao
L1
X
Figure 1 — Tooth dimensions — Profile system G
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ISO 13050:2014(E)
Detail of tooth face
For Ao ≥ x ≥ xo:
22
yA=+oI nA ox//Ao xx−11 −− / Ao (1)
() ()
where
xo corresponds to y = hg;
L1 is equal to bg − 2(Ao − xo).
NOTE 1 Indicated base tooth profile remains constant in all parts.
NOTE 2 “O” reference points remain in contact with the part outer surface generated by part radius of
curvature.
NOTE 3 Groove profile bottom surface in circular part form is an arc whose chordal distance is L1 and whose
radius originates at the part centre.
6.1.2 Belt widths and tolerances
Belt widths and tolerances are given in Table 2.
Table 2 — Widths and width tolerances
Dimensions in millimetres
Tolerance on width for belt pitch lengths
Over 840 mm and
Profile Nominal belt width
Up to and including Over
up to and including
840 mm 1 680 mm
1 680 mm
12 +0,8 −0,8 +0,8 −1,2 +0,8 −1,2
21 +0,8 −0,8 +0,8 −1,2 +0,8 −1,2
G8M
36 +0,8 −0,8 +0,8 −1,2 +0,8 −1,2
62 +1,2 −1,2 +1,2 −1,6 +1,6 −1,6
20 +0,8 −0,8 +0,8 −1,2 +0,8 −1,2
37 +0,8 −0,8 +0,8 −1,2 +0,8 −1,2
G14M 68 +1,2 −1,6 +1,6 −1,6 +1,6 −2,0
90 +1,6 −1,6 +1,6 −2,0 +2,0 −2,0
125 +2,4 −2,4 +2,4 −2,8 +2,4 −3,2
6.1.3 Pitch length measurement
See Annex A for tolerances and Annex B for the relationship between the centre distance and the belt
pitch length.
6.1.3.1 Measuring fixture (see Figure 3)
The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture
composed of the following elements.
6.1.3.1.1 Two pulleys of equal diameter, as specified in Table 3, of the proper belt profile and having
standard tooth space dimensions. These pulleys should be made to the tolerances shown in Table 3. 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.
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ISO 13050:2014(E)
6.1.3.1.2 Means of applying a total measuring force to the moveable pulley.
6.1.3.1.3 Means of measuring the centre distance between the two pulleys with the necessary
degree of accuracy for centre distance measurement.
6.1.3.2 Total measuring force
The total measuring force to be applied for measuring belts is given in Table 4.
6.1.3.3 Procedure
In measuring the pitch length of a synchronous belt, the belt should be rotated at least two revolutions
to seat it properly and to divide the total force equally between the two spans of the belt. The pitch
length shall be calculated by adding the pitch circumference of one of the pulleys to twice the measured
centre distance.
2
1
Key
1 centre distance
2 total measuring force
Figure 2 — Diagram of fixture for measuring pitch length
Table 3 — Belt length measuring pulleys
Dimensions in millimetres
Radial Axial
Number of Pitch circumfer- Outside diame-
runout runout
Profile
a
grooves ence ter
b b
F.I.M. F.I.M.
84,980
G8M 34 272 0,013 0,025
±0,013
175,454
G14M 40 560 0,013 0,051
±0,025
a
Pulleys outside of the diameter tolerance range specified can be used if the resulting belt length measurements are
corrected for the actual pulley diameters.
b
Full indicator movement.
NOTE The number of pulley teeth specified in Table 3 determines the recommended sizes for measuring the
belt pitch length. Practically, other sizes of pulleys could be used provided they have the same number of teeth,
and meet the dimensional requirements of Table 3.
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ISO 13050:2014(E)
Table 4 — Total measuring force
Forces in newtons
Belt width
mm
Profile
12 20 21 36 37 62 68 90 125
G8M 267 — 467 756 — 1223 — — —
G14M — 1179 — — 2046 — 3447 4315 5627
6.2 Pulleys, profile system G
6.2.1 General
See Annex C for tolerances.
The pulley is characterized by a curvilinear groove profile. This groove profile is defined as the profile
formed by the generating tool rack form required to machine-finish the curvilinear profile. The profile
is different for each pulley diameter, but can be closely approximated by a nominal groove profile over
specified ranges of number of grooves.
6.2.2 Generating tool rack
Dimensions and tolerances for the generating tool rack for pulleys with profile system G are given in
Table 5 and shown in Figure 3.
P
b
(0,0) P0
X
X
P1
X
P2
r1
X
r4 P3
r2
r3
h
r5
r
X
P4
r6
X
P5
r7
X
P6
r8
X
X P7
P8
X
Figure 3 — Pulley generating tool rack dimensions
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ISO 13050:2014(E)
8 © ISO 2014 – All rights reserved
Table 5 — Pulley generating tool rack dimensions
Dimensions in millimetres
Profile Number P h P r P r P r P r P r P r P r P r P X
b r 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8
of grooves
(X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y)
22 to 27 7,784 3,541 3,480 0,842 2,710 1,459 2,567 — — 8,833 2,427 5,882 1,841 3,123 1,324 1,450 0,979 0,552 0,856 0,856
0 −0,433 −0,788 −1,275 −2,580 −3,235 −3,491 −3,541
28 to 37 7,843 3,513 3,448 0,828 2,746 1,086 2,578 — — 9,487 2,447 5,901 1,894 3,152 1,367 1,505 1,009 0,640 0,843 0,843
0 −0,348 −0,715 −1,193 −2,486 −3,177 −3,447 −3,513
38 to 58 7,891 3,487 3,426 0,819 2,829 0,918 2,583 — — 9,964 2,462 5,921 1,940 3,181 1,410 1,562 1,024 0,669 0,831 0,831
G8M
0 −0,232 −0,668 −1,126 −2,402 −3,119 −3,414 −3,487
59 to 89 7,930 3,467 3,412 0,818 2,943 0,846 2,586 — — 10,385 2,470 5,932 1,978 3,205 1,443 1,614 1,039 0,725 0,820 0,820
0 −0,130 −0,632 −1,082 −2,328 −3,072 −3,384 −3,467
90 to 250 8,040 3,452 3,558 0,846 3,040 0,957 2,751 1,984 2,617 8,275 2,345 5,111 1,978 3,042 1,559 1,725 1,181 0,805 0,951 0,951
0 −0,164 −0,512 −0,873 −1,724 −2,495 −3,056 −3,359 −3,452
27 to 29 13,674 6,174 6,009 1,461 4,777 2,188 4,536 9,728 4,405 11,867 3,768 9,625 3,161 6,114 2,486 3,338 1,808 1,511 1,505 1,505
0 −0,684 −1,222 −1,696 −3,487 −4,619 −5,489 −6,041 −6,174
30 to 35 13,725 6,147 5,986 1,453 4,738 2,206 4,519 9,448 4,418 11,919 3,800 9,584 3,213 6,129 2,522 3,433 1,850 1,588 1,496 1,496
0 −0,717 −1,244 −1,626 −3,408 −4,531 −5,436 −5,990 −6,147
36 to 45 13,780 6,117 5,961 1,446 4,685 2,241 4,490 — — 13,051 3,951 10,115 3,297 6,163 2,582 3,489 1,883 1,672 1,485 1,485
0 −0,780 −1,312 −3,041 −4,387 −5,356 −5,942 −6,117
46 to 60 13,831 6,090 5,940 1,437 4,652 2,180 4,484 — — 13,091 3,971 10,092 3,417 6,222 2,649 3,541 1,913 1,745 1,476 1,476
G14M
0 −0,815 −1,313 −2,983 −4,172 −5,267 −5,899 −6,090
61 to 90 13,879 6,065 5,9190 1,429 4,608 2,151 4,484 — — 13,183 3,988 10,067 3,463 6,236 2,702 3,586 1,940 1,812 1,467 1,467
−0,883 −1,285 −2,928 −4,081 −5,193 −5,857 −6,065
91 to 149 13,927 6,040 5,900 1,420 4,568 2,586 4,476 — — 13,304 4,014 10,051 3,505 6,245 2,746 3,629 1,969 1,872 1,458 1,458
0 −0,955 −1,292 −2,848 −3,997 −5,128 −5,815 −6,040
150 to 250 13,956 6,024 5,887 1,414 4,537 5,757 4,458 — — 13,150 4,030 10,051 3,533 6,249 2,701 3,652 1,983 1,908 1,453 1,453
0 −1,031 −1,352 −2,799 −3,938 −5,171 −5,792 −6,024
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ISO 13050:2014(E)
6.2.3 Pulley groove profile dimensions and tolerances
Dimensions and tolerances for the pulley groove profile for G8M and G14M pulleys are given in Table 6
and shown in Figures 4 and 5.
Table 6 — Pulley groove profile dimensions
Dimensions in millimetres
Profile Number of b h R Ao xo L1 a
g g 1
grooves
G8M 22 to 89 5,400 3,43 0,80 2,29 0,379 1,60 0,80
90 to 250 5,660 3,43 0,80 2,29 0,379 1,60
G14M 28 to over 9,450 6,00 1,40 4,00 0,661 2,80 1,40
xo
b
g
R1
h
g
Y
X
Ao
L1
Figure 4 — Pulley groove profile
For Ao ≥ x ≥ xo:
22
yA=+oI nAox//Ao xx−11−− / Ao (2)
() ()
where
xo corresponds to y = hg;
L1 is equal to bg − 2(Ao − xo).
NOTE 1 Indicated base tooth profile remains constant in all parts.
NOTE 2 “O” Reference points remain in contact with the part outer surface generated by part radius of
curvature.
NOTE 3 Groove profile bottom surface in circular part form is an arc whose chordal distance is L1 and whose
radius originates at the part centre.
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ISO 13050:2014(E)
Key
1 pulley outside diameter
NOTE The true profile of the groove sides can only be produced by plotting the function associated with the
cross-section.
Figure 5 — Groove profile — Tolerance bands — Millimetres
6.2.4 Pulley outside diameters
Pulleys outside diameters for the standard pulleys are given in Table 7. The relationship of the pulley
outside and pitch diameters is illustrated in Figure 6 and Formulae (3) and (4).
No. of grooves×pulleyp itch
Pitchd iameter= (3)
π
Outside diameter = Pitch diameter − 2a (4)
where a is given in Table 1.
Key
1 pitch 4 pitch diameter
2 belt pitch line 5 outside diameter
3 belt tooth 6 pulley groove
Figure 6 — Pulley dimensions
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ISO 13050:2014(E)
Table 7 — Standard pulley sizes
Dimensions in millimetres
Profile
Number G8M G14M
of grooves
Pitch di- Outside Pitch di- Outside
ameter diameter ameter diameter
22 56,02 54,42
25 63,66 62,06
28 71,30 69,70 124,78 121,98
29 129,23 126,43
30 76,39 74,79 133,69 130,89
31 138,15 135,35
32 81,49 79,89 142,60 139,80
33 147,06 144,26
34 86,58 84,98 151,52 148,72
35 155,97 153,17
36 91,67 90,07 160,43 157,63
37 164,88 162,08
38 96,77 95,17 169,34 166,54
39 173,80 171,00
40 101,86 100,26 178,25 175,45
42 106,95 105,35
43 191,62 188,82
44 196,08 193,28
45 114,59 112,99 200,54 197,74
48 122,23 120,63 213,90 211,10
50 127,32 125,72 222,82 220,02
53 134,96 133,36 236,19 233,39
56 142,60 141,00 249,55 246,75
60
152,79 151,19 267,38 264,58
63 160,43 158,83 280,75 277,95
64 162,97 161,37 285,21 282,41
67 170,61 169,01 298,57 295,77
71 180,80 179,20 316,40 313,60
72 320,86 318,06
75 190,99 189,39 334,23 331,43
80 203,72 202,12 356,51 353,71
90 229,18 227,58 401,07 398,27
112 285,21 283,61 499,11 496,31
140 356,51 354,91 623,89 621,09
168 748,66 745,86
192 488,92 487,32
180 458,37 456,77 802,14 799,34
192 855,62 852,82
200 891,27 888,47
224 570,41 568,81 998,22 995,42
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ISO 13050:2014(E)
6.2.5 Pulley width
The standard nominal pulley width, and the minimum actual pulley width required, b for flanged
f
pulleys, b’ for unflanged pulleys are given in Table 8 and shown in Figure 7. Users are advised that the
f
values given for b’ apply also to pulleys with only one flange (see Annex D).
f
Table 8 — Standard pulley widths
Dimensions in millimetres
Minimum pulley width
Standard nominal
Profile
pulley width
Unflanged b’
Flanged b
f f
12 14 22
21 23 30
G8M
36 40 47
62 66 74
20 26 35
37 44 52
G14M 68 76 85
90 99 107
125 134 143
The minimum unflanged pulley width can be reduced when the alignment of the drive can be controlled,
but shall not be less than the minimum flanged pulley width.
b
b
f
f
1 2
Key
1 flanged pulley
2 unflanged pulley
Figure 7 — Minimum pulley width
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ISO 13050:2014(E)
7 Profile system H
7.1 Belt dimensions and tolerances
7.1.1 Belt tooth dimensions
The nominal belt tooth dimensions are the same for single-sided and double-sided belts; they are given
in Table 9 and shown in Figure 8.
Table 9 — Nominal tooth dimensions
Dimensions in millimetres
P P P P P P P P
1 5 2 6 3 7 4 8
a
Profile Pitch h h h r r a
s d t 1 2
(X, Y) (X, Y) (X, Y) (X, Y) (X, Y (X, Y) (X, Y) (X, Y
) )
−1,14 −0,83 −0,83 0,00
H3M 3 2,4 — 1,21 — 0,30 — — 0,86 — 0,381
0,00 −0,30 −0,35 −1,21
−1,14 −0,83 −0,83 0,00
DH3M 3 — 3,2 —
...
DRAFT INTERNATIONAL STANDARD
ISO/DIS 13050
ISO/TC 41/SC 4 Secretariat: ANSI
Voting begins on: Voting terminates on:
2013-12-02 2014-03-02
Synchronous belt drives — Metric pitch - Curvilinear
profile systems G, H, R and S - Belts and pulleys —
Complementary element
Transmissions par courroies synchrones à denture curviligne
[Revision of first edition (ISO 13050:1999)]
ICS: 21.220.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 13050:2013(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
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ISO/DIS 13050:2013(E)
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ii © ISO 2013 – All rights reserved
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ISO/DIS 13050
Contents Page
Foreword. vi
Introduction . vi
1 Scope. 1
2 Normative reference. 2
3 Synchronous belt drive system types.2
4 Belt nomenclature.3
5 Pulley nomenclature.3
6 Pulley system G.4
6.1 Belt dimensions and tolerances.4
6.1.1 Belt tooth dimensions.4
6.1.2 Belt widths and tolerances.4
6.1.3 Pitch length measurement.5
6.1.3.1 Measuring fixture.5
6.1.3.1.1 Two pulleys of equal diameter.5
6.1.3.1.2 Means of applying a total measing force.5
6.1.3.1.3 Means of measuring the centre distance.5
6.1.3.2 Total measuring force.5
6.1.3.3 Procedure.6
6.2 Pulleys, profile system G.7
6.2.1 General.7
6.2.2 Generating tooling rack.7
6.2.3 Pulley groove profile dimensions and tolerances.10
6.2.4 Pulley outside diameter.11
6.2.5 Pulley width.14
7 Pulley system H.15
7.1 Belt dimension and tolerances.15
7.1.1 Belt tooth dimension.15
7.1.2 Belt width and tolerances.16
7.1.3 Pitch length measurement.17
7.1.3.1 Measuring fixture.17
7.1.3.2 Two pulleys of equal diameter.17
7.1.3.3 Means of applying a total measuring force.17
7.1.3.4 Means of measuring the centre distance.17
7.1.3.5 Total measuring force.17
7.1.3.6 Procedure.17
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ISO/DIS 13050
7.2 Pulleys, profile system H.19
7.2.1 General.19
7.2.2 Generating tooling rack.19
7.2.3 Pulley groove profile dimensions and tolerances.23
7.2.4 Pulley outside diameter.25
7.2.5 Pulley width.27
8 Pulley system R.28
8.1 Belt dimension and tolerances.28
8.1.1 Belt tooth dimension.28
8.1.2 Belt width and tolerances.30
8.1.3 Pitch length measurement.30
8.1.3.1 Measuring fixture.30
8.1.3.1.1 Two pulleys of equal diameter.30
8.1.3.1.2 Means of applying a total force.30
8.1.3.1.3 Means of measuring the centre distance.31
8.1.3.2 Total measuring force.31
8.1.3.3 Procedure.31
8.2 Pulleys, profile system R.32
8.2.1 General.32
8.2.2 Generating tooling rack.32
8.2.3 Pulley groove profile dimensions and tolerances.33
8.2.4 Pulley outside diameter.35
8.2.5 Pulley width.37
9 Pulley system S.39
9.1 Belt dimension and tolerances.39
9.1.1 Belt tooth dimension.39
9.1.2 Belt width and tolerances.40
9.1.3 Pitch length measurement.40
9.1.3.1 Measuring fixture.40
9.1.3.1.1 Two pulleys of equal diameter.40
9.1.3.1.2 Means of applying a total force.41
9.1.3.1.3 Means of measuring the centre distance.
9.1.3.2 Total measuring force.41
9.1.3.3 Procedure.41
9.2 Pulleys, profile system S.42
9.2.1 General.42
9.2.2 Generating tooling rack.42
9.2.3 Pulley groove profile dimensions and tolerances.43
9.2.4 Pulley outside diameter.44
9.2.5 Pulley width.47
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ISO/DIS 13050
Annex A Belt pitch lengths and tolerances.48
Annex B Relationship between centre distance and belt pitch length.50
Annex C Pulley tolerance.51
C.1 Pitch to pitch tolerances.51
C.2 Diameter tolerances.51
C.3 Axial circular runout.52
C.4 Radial circular runout.52
C.5 Parallelism.52
C.6 Cylindricity.53
C.7 Taper.53
C.8 Quality specifications.53
Annex D Flange dimensions.54
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ISO/DIS 13050
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 13050 was prepared by Technical Committee ISO/TC 41, Belts and pulleys (including veebelts),
Subcommittee SC 4, Synchronous belt drives.
This second/third/. edition cancels and replaces the first/second/. edition (), [clause(s) / subclause(s) /
table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.
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ISO/DIS 13050
Synchronous belt drives — Metric pitch - Curvilinear profile
systems G, H, R and S - Belts and pulleys — Complementary
element
1 Scope
This International Standard specifies the principal characteristics of metric pitch curvilinear synchronous endless
1)
belts and pulleys in G, H, S and R profile systems for use in synchronous belt drives for mechanical power
transmission and where positive indexing or synchronization may 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; and tolerances;
d) belt length measurement specifications;
e) pulley groove dimensions and tolerances;
f) pulley diameter and width dimensions and tolerances;
g) pulley quality specification
1
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/DIS 13050
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute
provisions of this International Standard. For dated references, subsequent amendments to, or revisions of,
any of these publications do not apply. However, parties to agreements based on this International
Standard are encouraged to investigate the possibility of applying the most recent edition of the normative
document indicated below. For undated references, the latest edition of the normative document referred to
applies. Members of ISO and IEC maintain registers of currently valid International Standards.
ISO 254:1998, Belt drives -- Pulleys -- Quality, finish and balance.
ISO 1101:1983, Technical drawings -- Geometrical tolerancing -- Tolerancing of form, orientation, location
and run-out -- Generalities, definitions, symbols, indications on drawings.
3 Synchronous belt drive system types
Four profile systems and fourteen profiles for curvilinear synchronous drives are standardized.
Profile System G Profile System R
Profile G8M Profile R3M
(Tooth / groove pitch 8) (Tooth / groove pitch 3)
Profile G14M Profile R5M
(Tooth / groove pitch 14) (Tooth / groove pitch 5)
Profile R8M
(Tooth / groove pitch 8)
Profile R14M
(Tooth / groove pitch 14)
Profile R20M
(Tooth / groove pitch 20)
Profile System H Profile system S
Profile S8M
Profile H3M (Tooth / groove pitch 8)
(Tooth / groove pitch 3)
Profile S14M
Profile H5M (Tooth / groove pitch 14)
(Tooth / groove pitch 5)
Profile H8M
(Tooth / groove pitch 8)
Profile H14M
(Tooth / groove pitch 14)
Profile H20M
(Tooth / groove pitch 20)
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ISO/DIS 13050
4 Belt nomenclature
A belt is identified as follows:
a) the belt length or pitch length in millimeters, e.g. 1400 mm
b) the profile system, e.g. “G”,“H”, “R”, or “S”
c) the pitch or tooth pitch in millimetres; e.g. 14mm
d) the width or belt width in millimetres; e.g. 40mm (for Profile System S, the width in
millimetres x 10)
e) double-sided belts are designated by adding the letter "D" before the designation of the
profile system
EXAMPLE – A synchronous belt in the above profile systems of 1400mm length, 14mm pitch and
40mm wide is identified as follows:
Profile System G Profile System R
1400-G14M-40 1400-R14M-40
1400-DG14M-40 1400-DR14M-40
Profile System H Profile System S
1400-H14M-40 1400-S14M-400
1400-DH14M-40 1400-DS14M-400
5 Pulley nomenclature
A pulley is identified as follows:
a) the letter “P” indicates a pulley
b) the number of grooves; e.g. 30
c) the profile system, e.g. “G“, “H”, “R”, or “S”
d) the pitch or groove pitch in millimetres; e.g. 14mm
e) the width or belt width in millimetres; e.g. 40mm (for Profile System S, the width in millimetres x
10)
EXAMPLE – A pulley in the above profile systems of 30 grooves, 14mm pitch and 40mm wide is
identified as follows:
Profile System G Profile System R
P30-G14M-40 P30-R14M-40
Profile System H Profile System S
P30-H14M-40 P30-S14M-400
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DIS 13050
6 Profile system G
6.1 Belt dimensions and tolerances
6.1.1 Belt tooth dimensions
The nominal belt tooth dimensions are given in Table 1 and shown in Figure 1.
Table 1 – Nominal tooth dimensions
Dimensions in millimetres
a
Profile Belt Ao a xo L1
b h R
g g 1
Pitch
G8M 8 5,200 3,43 0,74 2,29 0,80 0,379 1,378
G14M 14 9,100 6,00 1,30 4,00 1,40 0,661 2,422
a
a is the belt design pitch differential.
Figure 1 – Tooth Dimensions – Profile System G
Detail of Tooth Face
For Ao > x > xo:
2 2
� �
� �
y � ln Ao / x � �Ao / x� �1 � 1��x / Ao�
� �
� �
� �
� �
Where: xo corresponds to y=hg
L1 = bg - 2�Ao-xo�
NOTES:
1. Indicated base tooth profile remains constant in all parts.
2. “O” Reference points remain in contact with the part outer surface generated by part radius of curvature.
3. Groove profile bottom surface in circular part form is an arc whose chordal distance is L1 and whose radius originates
at the part center.
6.1.2 Belt widths and tolerances
Belt widths and tolerances are given in Table 2.
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ISO/DIS 13050
Table 2 — Widths and width tolerances
Dimensions in millimetres
Tolerance on width for belt pitch lengths
Over 840 mm and up to
Profile Nominal belt width
Up to and including Over
and including
840 mm 1 680 mm
1 680 mm
12 +0,8 -0,8 +0,8 -1,2 +0,8 -1,2
21 +0,8 -0,8 +0,8 -1,2 +0,8 -1,2
G8M
36 +0,8 -0,8 +0,8 -1,2 +0,8 -1,2
62 +1,2 -1,2 +1,2 -1,6 +1,6 -1,6
20 +0,8 -0,8 +0,8 -1,2 +0,8 -1,2
37 +0,8 -0,8 +0,8 -1,2 +0,8 -1,2
G14M 68 +1,2 -1,6 +1,6 -1,6 +1,6 -2,0
90 +1,6 -1,6 +1,6 -2,0 +2,0 -2,0
125 +2,4 -2,4 +2,4 -2,8 +2,4 -3,2
6.1.3 Pitch length measurement
See annex A for tolerances and annex B for the relationship between the centre distance and the belt pitch length.
6.1.3.1 Measuring fixture (see Figure 3)
The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture composed of the
following elements.
6.1.3.1.1 Two pulleys of equal diameter, as specified in Table 3, of the proper belt type and having standard tooth
space dimensions. These pulleys should be made to the tolerances shown in Table 3. 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.
6.1.3.1.2 Means of applying a total measuring force to the moveable pulley.
6.1.3.1.3 Means of measuring the centre distance between the two pulleys with the necessary degree of accuracy
for centre distance measurement.
6.1.3.2 Total measuring force
The total measuring force to be applied for measuring belts is given in Table 4.
6.1.3.3 Procedure
In measuring the pitch length of a synchronous belt, the belt should be rotated at least two revolutions to seat it properly
and to divide the total force equally between the two spans of the belt. The pitch length shall be calculated by adding the
pitch circumference of one of the pulleys to twice the measured centre distance.
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ISO/DIS 13050
Key
1 Centre distance
2 Total measuring force
Figure 2 - Diagram of fixture for measuring pitch length
Table 3 – Belt length measuring pulleys
Dimensions in millimetres
Profile Numberof Pitch Outside Radial Axial
a
grooves circumference diameter runout runout
b b
F.I.M. F.I.M.
84,980
G8M 34 272 0,013 0,025
±0,013
175,454
G14M 40 560 0,013 0,051
±0,025
a
Pulleys outside of the diameter tolerance range specified may be used if the
resulting belt length
measurements are corrected for the actual pulley diameters.
b
Full Indicator movement
NOTE The number of pulley teeth specified in Table 3 determine the recommended sizes
for measuring the belt pitch length. Practically, other sizes of pulleys could be used provided
they have the same number of teeth, and meet the dimensional requirements of Table 3.
Table 4 – Total measuring force
Forces in newtons
Profile Belt Width (mm)
12 20 21 36 37 62 68 90 125
G8M
267 467 756 1223
G14M
1179 2046 3447 4315 5627
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ISO/DIS 13050
6.2 Pulleys, profile system G
6.2.1 General
See annex C for tolerances.
The pulley is characterized by a curvilinear groove profile. This groove profile is defined as the profile formed by the
generating tool rack form required to machine-finish the curvilinear profile. The profile is different for each pulley diameter,
but can be closely approximated by a nominal groove profile over specified ranges of number of grooves.
6.2.2 Generating tool rack
Dimensions and tolerances for the generating tool rack for pulleys with profile system G are given in Table 5 and shown
in Figure 3.
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DIS 13050 ISO/CD 13050
Table 5 – Pulley generating tool rack dimensions
Dimensions in millimetres
P h r r r r
Profile Number of b r P P r P P r P P r P r P
0 1 1 2 2 3 P3 4 4 5 5 6 6 7 7 8 8 X
Grooves
(X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y)
---- 0,552
22 thru 27 7,784 3,541 3,480 0,842 2,710 1,459 2,567 ---- 8,833 2,427 5,882 1,841 3,123 1,324 1,450 0,979 0,856 0,856
-0,788 -3,491
0 -0,433 -1,275 -2,580 -3,235 -3,541
---- 0,
28 thru 37 7,843 3,513 3,448 0,828 2,746 1,086 2,578 ---- 9,487 2,447 5,901 1,894 3,152 1,367 1,505 1,009 640 0,843 0,843
-0,715 -3,447
0 -0,348 -1,193 -2,486 -3,177 -3,513
----
38 thru 58 7,891 3,487 3,426 0,819 2,829 0,918 2,583 ---- 9,964 2,462 5,921 1,940 3,181 1,410 1,562 1,024 0,669 0,831 0,831
-0,668 -3,414
0 -0,232 -1,126 -2,402 -3,119 -3,487
G8M
----
59 thru 89 7,930 3,467 3,412 0,818 2,943 0,846 2,586 ---- 10,385 2,470 5,932 1,978 3,205 1,443 1,614 1,039 0,725 0,820 0,820
-0,632 -3,384
0 -0,130 -1,082 -2,328 -3,072 -3,467
1,
90 thru 250 8,040 3,452 3,558 0,846 3,040 0,957 2,751 984 2,617 8,275 2,345 5,111 1,978 3,042 1,559 1,725 1,181 0,805 0,951 0,951
-0,512 -3,359
0 -0,164 -0,873 -1,724 -2,495 -3,056 -3,452
27 thru 29 13,674 6,174 6,009 1,461 4,777 2,188 4,536 9,728 4,405 11,867 3,768 9,625 3,161 6,114 2,486 3,338 1,808 1,511 1,505 1,505
0 -0,684 -1,222 -1,696 -3,487 -4,619 -5,489 -6,041 -6,174
30 thru 35 13,725 6,147 5,986 1,453 4,738 2,206 4,519 9,448 4,418 11,919 3,800 9,584 3,213 6,129 2,522 3,433 1,850 1,588 1,496 1,496
0 -0,717 -1,244 -1,626 -3,408 -4,531 -5,436 -5,990 -6,147
36 thru 45 13,780 6,117 5,961 1,446 4,685 2,241 4,490 ---- ---- 13,051 3,951 10,115 3,297 6,163 2,582 3,489 1,883 1,672 1,485 1,485
0 -0,780 -1,312 -3,041 -4,387 -5,356 -5,942 -6,117
46 thru 60 13,831 6,090 5,940 1,437 4,652 2,180 4,484 ---- ---- 13,091 3,971 10,092 3,417 6,222 2,649 3,541 1,913 1,745 1,476 1,476
0 -0,815 -1,313 -2,983 -4,172 -5,267 -5,899 -6,090
G14M
61 thru 90 13,879 6,065 5,919 1,429 4,608 2,151 4,484 ---- ---- 13,183 3,988 10,067 3,463 6,236 2,702 3,586 1,940 1,812 1,467 1,467
0 -0,883 -1,285 -2,928 -4,081 -5,193 -5,857 -6,065
91 thru 149 13,927 6,040 5,900 1,420 4,568 2,586 4,476 ---- ---- 13,304 4,014 10,051 3,505 6,245 2,746 3,629 1,969 1,872 1,458 1,458
0 -0,955 -1,292 -2,848 -3,997 -5,128 -5,815 -6,040
150 thru
250 13,956 6,024 5,887 1,414 4,537 5,757 4,458 ---- ---- 13,150 4,030 10,051 3,533 6,249 2,701 3,652 1,983 1,908 1,453 1,453
0 -1,031 -1,352 -2,799 -3,938 -5,171 -5,792 -6,024
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ISO/DIS 13050
Figure 3 - Pulley generating tool rack dimensions
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DIS 13050
6.2.3 Pulley groove profile dimensions and tolerances
Dimensions and tolerances for the pulley groove profile for G8M and G14M pulleys are given
in Table 6 and s
...
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