NWP Curvilinear toothed synchronous belt drive systems ISO/NWP Date: ISO/TC41/SC4/N 445. Warning

Transcription

1 Date: ISO/TC41/SC4/N 445 NWP 135 Curvilinear toothed synchronous belt drive systems Warning This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an International Standard. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation. ii ISO 25 All Rights Reserved

2 Copyright Notice This ISO document is a working draft or committee draft and is copyright-protected by ISO. While the reproduction of working drafts or committee drafts in any form for use by participants in the ISO standards development process is permitted without prior permission from ISO, neither this document nor any extract from it may be reproduced, stored or transmitted in any form for any other purpose without prior written permission from ISO. Requests for permission to reproduce this document for the purpose of selling it should be addressed as shown below or to ISO's member body in the country of the requester: American National Standards Institute (ANSI), 1819 L Street, N.W., 6th Floor, Washington D.C. 236; tel: ; fax: ; Reproduction for sales purposes may be subject to royalty payments or a licensing agreement. Violators may be prosecuted. i ISO 25 All Rights Reserved

3 Contents Page Foreword...iv 1 Scope Normative reference Belt types Belt nomenclature Pulley types Pulley nomenclature Type H system H-type belt dimensions and tolerances Belt tooth dimensions Belt widths and tolerances Pitch length measurement H-type pulleys General Generating tool rack Pulley groove profile dimensions and tolerances Pulley outside diameters Pulley width Type R system R-type belt dimensions and tolerances Belt tooth dimensions Belt widths and tolerances Pitch length measurement R-type pulleys General Generating tool rack Pulley groove profile dimensions and tolerances Pulley outside diameters Pulley width Type S system S-type belt dimensions and tolerances Belt tooth dimensions Belt widths and tolerances Pitch length measurement S-type pulleys General Generating tool rack Pulley groove profile dimensions and tolerances Pulley outside diameters Pulley width...36 Annex A...38 Belt pitch lengths and tolerances...38 Annex B...4 Relationship between centre distance and belt pitch length...4 ISO 25 All Rights Reserved ii

4 Annex C...41 C.1 Pitch to pitch tolerances...41 C.2 Diameter tolerances...41 C.3 Axial circular runout...42 C.4 Radial circular runout...42 C.5 Parallelism...42 C.6 Cylindricity...43 C.7 Taper...43 C.8 Quality specifications...43 Annex D...44 iii ISO 25 All Rights Reserved

5 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 135 was prepared by Technical Committee ISO/TC 41, Pulleys and belts, Subcommittee SC 4, Synchronous belt drives. This third edition cancels and replaces the second edition (24), which has been technically revised. ISO 25 All Rights Reserved iv

6 Curvilinear toothed synchronous belt drive systems 1 Scope This International Standard specifies the principal characteristics of synchronous endless belts and pulleys for use in synchronous belt drives 1) 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) Synchronous belt drives have been known by various titles in the past: for example, timing belt drives, positive belt drives, gear belt drives ISO 25 All Rights Reserved

7 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 111:1983, Technical drawings -- Geometrical tolerancing -- Tolerancing of form, orientation, location and run-out -- Generalities, definitions, symbols, indications on drawings. 2 Belt types Twelve belt types for synchronous drives are standardized: - Type H3M (H Type Tooth Profile) - Type R3M (R Type Tooth Profile) - Type H5M (H Type Tooth Profile) - Type R5M (R Type Tooth Profile) - Type H8M (H Type Tooth Profile) - Type R8M (R Type Tooth Profile) - Type S8M (S Type Tooth Profile) - Type H14M (H Type Tooth Profile) - Type R14M (R Type Tooth Profile) - Type S14M (S Type Tooth Profile) - Type H2M (H Type Tooth Profile) - Type R2M (R Type Tooth Profile) 3 Belt nomenclature A belt is identified by a combination of numbers and letters as follows: a) the belt pitch length in millimetres; b) the type of tooth profile; c) the tooth pitch in millimetres; d) the width in millimetres or 1 times the width in millimetres for the S-type belt; ISO 25 All Rights Reserved - 2 -

8 e) double-sided belts are designated by adding the letter "D" before the tooth profile letter. EXAMPLE - A curvilinear tooth synchronous belt of 14 mm pitch, 4 mm wide, 1 4 mm pitch length is identified as follows: 14-H14M-4 for H-type single-sided belt, 14-DH14M-4 for H-type double-sided belt; 4-S14M-14 for S-type single-sided belt, 4-DS14M-14 for S-type double-sided belt; 14-R14M-4 for R-type single-sided belt, 14-DR14M-4 for R-type double-sided belt. 4 Pulley types Twelve pulley types for synchronous drives are standardized: - Type H3M (H Type Groove Profile) - Type R3M (R Type Groove Profile) - Type H5M (H Type Groove Profile) - Type R5M (R Type Groove Profile) - Type H8M (H Type Groove Profile) - Type R8M (R Type Groove Profile) - Type S8M (S Type Groove Profile) - Type H14M (H Type Groove Profile) - Type R14M (R Type Groove Profile) - Type S14M (S Type Groove Profile) - Type H2M (H Type Groove Profile) - Type R2M (R Type Groove Profile) 5 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 identified, as is the belt, by a combination of numbers and letters as follows: a) the letter "P" indicates a pulley; b) the number of grooves; c) the type of groove profile; d) the groove pitch in millimetres; e) the width in millimetres or ten times the width in millimetres for S-type pulleys ISO 25 All Rights Reserved

9 EXAMPLE - A pulley for a curvilinear toothed belt which has 14 mm pitch and 3 grooves with a nominal width of 4 mm is identified as follows: P3-H14M-4 for H-type pulleys; P3-S14M-4 for S-type pulleys; P3-R14M-4 for R-type pulleys. ISO 25 All Rights Reserved - 4 -

10 8 Type H system 8.1 H-type belt dimensions and tolerances Belt tooth dimensions 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. Table 1 Nominal tooth dimensions Belt Section Pitch h s h d h t P 1 (X,Y) P 5 (X,Y) r 1 P 2 (X,Y) P 6 (X,Y) P 3 (X,Y) P 7 (X,Y) r 2 P 4 (X,Y) P 8 (X,Y) a H3M 3 2,4 1,21-1,14, DH3M 3 3,2 H5M 5 3,8 2,8-1,85, DH5M 5 5,3 H8M 8 6, 3,38-3,3, DH8M 8 8,1 H14M 14 1, 6,2-5,78, DH14M 14 14,8 H2M ,68-8,34,,3-1,14,76,41-1,85 1,14,76-3,3 1,37 1,42-5,78 2,79 2,3 -,83 -,3,3-1,44 -,42,41-2,55 -,65,76-4,36-1,29 1,42-6,32-1,84 -, ,44 1,56-2,55 2,2-4,36 4,8 -,83 -,35-1,44 -,53-2,47-1,17-4,3-1,97-6,22-2,9,86 -,83 1,11 1,5-1,44 1,67 2,59-2,47 2,54 4,46-4,3 4,76 6,4, -1,21,86, -2,8 1,5, -3,38 2,59, -6,2 4,46, -8,68,381, 1,97,381,572, 3,22,572,686, 4,75,686 1,397, 8,81 1,397 2,159 P8 X X h P1 X P2 s h P3 X t r 2 r 1 a h d h t a P7X P5 XP6 X X P1 X P2 P3 X r 2 r 1 r r 2 1 a X P4 X P4 Single-Sided Belts Double-Sided Belts Figure 1 Tooth Dimensions H Type Profile ISO 25 All Rights Reserved

11 7.1.2 Belt widths and tolerances Belt widths and tolerances are given in Table 2. Table 2 Widths and width tolerances Tolerance on width for belt pitch lengths Belt type Nominal belt width Up to and including 84 mm Over 84 mm and up to and including 1 68 mm Over 1 68 mm H3M 6 9 +,4,8 +,4,8 DH3M 15 +,8,8 +,8 1,2 +,8 1,2 H5M 9 +,4,8 +,4,8 DH5M ,8,8 +, ,8 1.2 H8M DH8M ,8,8 +,8 1,2 + 1,6 1,6 +,8 1,2 + 1,2 1,2 + 1,6 2, +,8 1,2 + 1,2 1,6 + 2, 2, H14M ,8 1,2 + 1,2 1, ,2 + 1,2 1,6 + 1,2 1,6 + 1,6 1,6 85 DH14M H2M ,6 1,6 + 2,4 2,4 + 2,4 2,4 + 1,6 2, + 2,4 2,8 + 2,4 2,8 + 2, 2, + 2,4 3,2 + 2,4 3,2 + 4,8 6, Pitch length measurement See annex A for tolerances and annex B for the relationship between the centre distance and the belt pitch length. ISO 25 All Rights Reserved - 6 -

12 Measuring fixture (see Figure 11) The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture composed of the following elements 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 Means of applying a total measuring force to the moveable pulley Means of measuring the centre distance between the two pulleys with the necessary degree of accuracy for centre distance measurement Total measuring force The total measuring force to be applied for measuring belts is given in Table 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. Check double-sided belts on both tooth faces. Total Measuring Force Centre Distance Figure 2 Diagram of fixture for measuring pitch length ISO 25 All Rights Reserved

13 Table 3 Belt length measuring pulleys Belt type Number of grooves Pitch circumference Outside diameter a Radial runout F.I.M. b Axial runout F.I.M. b H3M, DH3M 3 9 H5M, DH5M 2 1 H8M, DH8M H14M, DH14M 4 56 H2M ,886,13 3,687,13 85,28,13 175,46,25 25,33,36,13,25,13,25,13,25,13,51,13,76 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 Belt Belt width (mm) Pitch H3M, DH3M H5M, DH5M H8M, DH8M H14M, DH14M H2M ISO 25 All Rights Reserved - 8 -

14 7.2 H-type pulleys 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 Generating tool rack Dimensions and tolerances for the generating tool rack for H-type pulleys are given in Table 5 and shown in Figure ISO 25 All Rights Reserved

15 Table 5 Pulley generating tool rack dimensions Belt Section Number of Grooves Pb ±,12 hr ±,15 Po (X,Y) r 1 ±,12 P 1 (X,Y) r 2 ±,12 P 2 (X,Y) r 3 ±,12 P 3 (X,Y) r 4 ±,12 X P 4 r 5 P 5 (X,Y) (X,Y) ±,12 H3M 9 thru 13 3, 1,196 1,423,414 1,61 -,213,712 -,84,559,574-1,4,869,29-1,196,29 14 thru 25 3, 1,173 1,324,254 1,139 -,8,792,992 -,3,747 -,86,254,687 -,944,844,114-1,168, thru 8 3, 1,227 1,223,262,982 -,159 2,616,82 -,679 -,493,733 -,877,869,36-1,227,36 81 thru 2 3, 1,232 1,333,358,981 -,29,923 -,554,866,77-1,232,77 H5M 12 thru 16 5, 1,986 2,344,659 1,739 -,316 4,475 1,522 -,72 1,124-1,56,691,773-1,895 1,133,328-1,986, thru 31 5, 2,24 2,242,61 1,871 -,126 1,431 1,54 -,593 1,163-1,566,612 1,13-1,789 1,219,295-2,24, thru 79 5, 2,32 2,73,493 1,675 -,23 1,359 1,51 -,566 1,37-1,35 1,42 1,88-1,617 1,3,135-2,32,135 8 thru 2 5, 2,65 2,16,61 1,564 -,483 1,443-1,5 1,471,43-2,65, ISO 25 All Rights Reserved

16 Table 5 Continued Pulley generating tool rack dimensions Belt Section Number of Grooves Pb ±,12 hr ±,15 Po (X,Y) r 1 ±,12 P 1 (X,Y) r 2 ±,12 P 2 (X,Y) r 3 ±,12 P 3 (X,Y) r 4 ±,12 P 4 (X,Y) r 5 P 5 X ±,12 (X,Y) H8M 22 thru 27 8, 3,289 3,85 1,143 2,738 -,648 2,322-1,81 2,553-3, thru 89 8, 3,612 3,754 1,67 2,748 -,711 12,93 2,36-2,24,726 2,283-2,215 2,744-3,612 9 thru 2 8, 3,632 3,617,94 2,697 -,757 2,459-1,948 2,637-3,632 H14M 28 thru 36 14, 6,32 6,761 1,88 5,37-1,133 2,828 4,64-3,94 1,143 3,99-4,242 4,717-6,32 37 thru 89 14, 6,223 6,599 1,829 4,89-1,176 15,748 4,24-3,493 1,143 4,89-3,82 4,663-6,223 9 thru , 6,35 6,546 1,95 4,74-1,425 2,117 4,288-3,439,254 4,27-3,498 4,623-6,35 H2M 34 thru 45 2, 8,644 9,786 2,814 7,15-1,852 5,972-4,947 5,625,753-8,644, thru 1 2, 8,591 9,529 2,667 7,41-1,662 2,329 6,15-5,121 5,842,711-8,591, thru 22 2, 8,69 9,787 2,676 7,35-1,76 6,165-4,855 5,833,739-8,69, ISO 25 All Rights Reserved

17 Figure 3 Pulley generating tool rack form ISO 25 All Rights Reserved

18 7.2.3 Pulley groove profile dimensions and tolerances Dimensions and tolerances for the pulley groove profile for H3M, H5M, H8M, H14M and H2M pulleys are given in Table 6 and shown in Figure 4. Table 6 Pulley groove profile dimensions Belt Section Number of Grooves Hg X R 1 R 2 1 thru 13 1,19,29,991 15,181 H3M 14 thru 25 1,179,112,889 9, thru 8 1,219,28,927 8, thru 2 1,234,74,925 4,31 12 thru 16 1,989,37 1,265 1,432 H5M 17 thru 25 2,9,32 1,27 6,58 26 thru 8 2,52,81 1,438 2, thru 2 2,56,28 1,552 5, thru 27 3,295, 2,675 11,3,874 H8M 28 thru 89 3,64, 2, ,24 9 thru 2 3,63, 2,639 6,6 1,8 28 thru 32 6,327, 4,859 7,1 1, thru 36 6,328, 4,834 5,2 1, thru 57 6,198, 4,737 9,3 1,654 H14M 58 thru 89 6,198, 4,669 8,9 1,92 9 thru 153 6,328, 4,636 6,9 1, thru 216 6,327, 4,597 8,6 1,77 32 thru 45 8,649,544 6, ,184 H2M 46 thru 1 8,661,544 6, ,54 11 thru 22 8,7,544 6, ,54 Profile Band a,51,51 +,9 -,8 +,9 -,8,89 a the profile band tolerance thru R2 blends into the pulley OD tolerance so that the pulley OD and profile band tolerances do not conflict. Ø Figure 4 Pulley groove profile and tolerance bands ISO 25 All Rights Reserved

19 7.2.4 Pulley outside diameters Pulley outside diameters for the standard pulleys are given in Table 7. The relationship of the pulley outside and pitch diameters is illustrated in Figure 5 and the following formula. Table 8 provides the N' values to be used in the outside diameter formula. pitch diameter = No.of grooves x pulley pitch outside diameter = pitch diameter - 2a + N' where a is the value given in Table 1. Figure 5 Pulley dimensions ISO 25 All Rights Reserved

20 ISO 25 All Rights Reserved Table 7 Standard pulley sizes Pulley type H3M H5M H8M H14M H2M Number of grooves Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter ,37 14,32 15,28 16,23 17,19 18,14 19,1 12,61 13,56 14,52 15,47 16,43 17,38 18,34 22,28 23,87 25,46 27,6 28,65 3,24 31,83 21,14 22,73 24,32 25,91 27,5 29,1 3, ,5 21,1 22,92 24,83 26,74 28,65 19,29 2,25 22,16 24,7 25,98 27,89 33,42 35,1 38,2 41,38 44,56 47,75 32,28 33,87 37,5 4,24 43,42 46,6 56,2 a 61,12 a ,21 a 71,3 a 76,39 a 54,65 59, ,84 7,8 75,13 124,78 a 129,23 a 133,69 a 122,12 126,57 13, ,56 32,47 34,38 36,29 38,2 41,6 42,2 43,93 29,8 31,71 33,62 35,53 37,44 4,3 41,25 43,16 5,93 54,11 57,3 6,48 63,66 68,44 7,3 73,21 49,79 52,97 56,15 59,34 62,52 67,29 68,89 72,7 81,49 86,58 91,67 96,77 11,86 112,5 8,16 85,21 9,3 95,39 1,49 11,67 142,6 a 151,52 a 16,43 169,34 178,25 196,8 139,88 148,79 157,68 166,6 175,49 193,28 216,45 229,18 241,92 254,65 28,11 212,13 224,87 237,6 25,33 275, ,48 46,79 47,75 49,66 52,52 57,3 45,7 46,3 46,98 48,89 51,76 56,53 76,39 77,99 79,58 82,76 87,54 89,13 95,49 98,68 75,25 76,84 78,43 81,62 86,39 87,98 94,35 97,53 122,23 142,6 12,86 141,23 213,9 231,73 249,55 267,38 211,11 228,94 246,76 264,59 35,58 331,4 356,51 381,97 31,26 326,72 325,19 377, ,7 66,85 68, ,48 76,39 85,94 95,49 61,31 66,8 67, ,72 75,63 85,18 94,73 13,45 111, ,14 127,32 143,24 159,15 12,31 11, , 126,18 142,1 158,1 162,97 183,35 23,72 229,18 161,6 181,97 22,35 227,81 285,21 33,3 32,86 356,51 41,7 282,41 3,24 318,6 353,71 398,28 47,44 432,9 452, 59,3 572,96 43,12 428,58 447,68 54,98 568, ,4 114,59 124,14 133,69 143,24 152,79 14,28 113,83 123,38 132,92 142,48 152,3 175,7 19,99 26,9 222,82 238,73 254,65 173,93 189,84 25,76 221,67 237,59 235,5 285,21 a 366,69 a ,83 365, ,11 641,71 748,66 a 496,32 638,92 745,87 713,1 916, ,52 78,7 912, , ,92 a 487,55 855,62 a 962,57 a 852,82 959, , , a Usually not available in all widths -- consult supplier.

21 Table 8 Values of N' Pulley type Number of grooves H8M H14M Value of N' Value of N' ,15,15,1,8,5,3,15,13,9,9,8,8,8,5,5,5,5,3,3 Note: N values for H3M, H5M, and H2M are zero Pulley width The standard nominal pulley width, and the minimum actual pulley width required, b f for flanged pulleys, b' f for unflanged pulleys are given in Table 9 and shown in Figure 6. Users are advised that the values given for b' f apply also to pulleys with only one flange (see Annex D). Table 9 Standard pulley widths Pulley type Standard nominal Minimum pulley width pulley width Flanged b f Unflanged b' f H3M H5M H8M H14M H2M ISO 25 All Rights Reserved The minimum unflanged pulley width may be reduced when the alignment of the drive can be controlled but shall not be less than the minimum flanged pulley width.

22 Figure 6 Minimum pulley width 8 Type R system 8.1 R-type belt dimensions and tolerances 8,1.1 Belt tooth dimensions The nominal belt tooth dimensions are the same for single-sided and double-sided belts; they are given in Table 1 and shown in Figure 7. Table 1 Nominal tooth dimensions Belt type Pitch S h s h d h t r r a a C R3M ,95 2,4 1,27,38,381 3,567 DR3M ,95 3,3 1,27,38,381 3,567 R5M ,3 3,8 2,15,63,57 1,795 DR5M ,3 5,44 2,15,63,57 1,795 R8M ,49 5,4 3,25 1,,686 1,954 DR8M ,49 8,37 3,25 1,,686 1,954 R14M ,61 9,7 6,13 1,75 1,397,625 DR14M ,61 15,5 6,13 1,75 1,397,625 R2M ,75 14,5 8,75 2,5 2,16,438 a is the belt design pitch differential ISO 25 All Rights Reserved

23 Figure 7 Belt tooth dimensions ISO 25 All Rights Reserved

24 8.1.2 Belt widths and tolerances Belt widths and tolerances are given in Table 11. Belt type R3M Nominal belt width 6 9 DR3M 15 R5M DR5M R8M DR8M R14M DR14M R2M Table 11 Widths and width tolerances Tolerance on width for belt pitch lengths Up to and including 84 mm +,4,8 +,8,8 +,4,8 +,8,8 +,8,8 +,8 1,2 + 1,6 1,6 +,8 1,2 + 1,2 1,2 + 1,6 1,6 + 2,4 2,4 + 2,4 2,4 Over 84 mm and up to and including 1 68 mm +,4,8 +,8-1,2 +,4,8 +,8 1,2 +,8 1,2 + 1,2 1,2 + 1,6 2, ,2 + 1,2 1,6 + 1,6 2, + 2,4 2,8 + 2,4 2,8 Over 1 68 mm +,8 1,2 +,8 1,2 +,8 1,2 + 1,2 1,6 + 2, 2, + 1,2 1,6 + 1,6 1,6 + 2, 2, + 2,4 3,2 + 2,4 3,2 + 4,8 6, Pitch length measurement See Annex A for tolerances and annex B for the relationship between the centre distance and the belt pitch length Measuring fixture (see Figure 24) The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture composed of the following elements Two pulleys of equal diameter, as specified in Table 12 of the proper belt type and having standard tooth space dimensions. These pulleys should be made to the tolerances shown in Table 12. 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 Means of applying a total measuring force to the moveable pulley ISO 25 All Rights Reserved

25 Means of measuring the centre distance between the two pulleys with the necessary degree of accuracy for centre distance measurement Total measuring force The total measuring force to be applied for measuring belts is given in Table 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 lengths 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. Check double-sided belts on both tooth faces. Total Measuring Force Centre Distance Figure 8 Diagram of fixture for measuring pitch length a Belt type Table 12 Belt length measuring pulleys Number of grooves Pitch circumference R3M, DR3M 3 9 R5M, DR5M 2 1 R8M, DR8M R14M, DR14M 4 56 R2M 4 8 Outside diameter a 27,886,13 3,687,13 85,28,13 175,46,25 25,33,36 Radial Axial runout runout F.I.M. b F.I.M. b,13,25,13,25,13,25,13,51,13,76 For pulleys outside of the diameter tolerance range specified consult the belt manufacturer. b Full Indicator Movement NOTE: The number of pulley teeth specified in Table 12 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 12. ISO 25 All Rights Reserved - 2 -

26 Table 13 Total measuring force Forces in Newtons Belt Belt width (mm) pitch R3M, DR3M R5M, DR5M R8M, DR8M R14M, DR14M R2M R-type pulleys 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 Generating tool rack Dimensions and tolerances for the generating tool rack for R8M and R14M pulleys are given in Table 14 and Figure ISO 25 All Rights Reserved

27 Pulley type Number of grooves R3M ,761 16, R3M ,867 16, R3M 31 and over 3, 16, R5M ,761 16, R5M 22 and over 5, 16, R8M ,78 18, R8M 28 and over 7,89 18, R14M 28 and over 13,8 18, R2M 3 and over 19,692 18, Table 14 Pulley generating tool rack dimensions P b A h b p W,12,5 t h p W r r ref. r W 2 ref. ref. t C,25 2,6 +,5 -, 2,6 +,5 -, 2, +,5 -, 3,48,25 3,48,25 5,9,25 5,9,25 1,45 +,5 -, 14,85 +,5 -,,925,925,896 1,64 1,64 2,828 2,794 4,93 6,73 1,15,25 1,15,25 1,2,25 2,6 +,5 -, 2,6 +,5 -, 3,45 + -,5 3,45 + -,5 6,4 +,5-8,5 +,5 -,966,234,966,34,913,367 1,69,332 1,69,571 2,75,577 2,74,612 4,87 1,2 6,841 1,64,87 +,5 -,,87 +,5 -,,798 +,5 -, 1,379,25 1,379,25 1,82,25 1,84,25 3,32,25 4,97,25,31 3,285,31 3,285,41 3,394,63 1,896,63 1,896,9,837 3,95, ,6, ,6,353 2 Figure 9 Pulley generating tool rack form Pulley groove profile dimensions and tolerances Dimensions and tolerances for the pulley groove profile for R-type pulleys are given in Table 15 and Table 16 and shown in Figures 1 and 11. ISO 25 All Rights Reserved

28 Table 15 Pulley groove profile dimensions Belt Number of section teeth GH X A X B Y B X' c Y' c K r t R D ,15,39 4,,8,54,94 3,21,28 4, R3M ,15,4 4,,,53,93 3,285,3 13, 31 and over 1,2,4 4,,,53,93 3,394,4 18, R5M ,6,63 4,,6,97 1,7 1,79,63 9, 22 and over 2,6,7 4,,,95 1,66 1,829,5 18, R8M ,47,92 4,,11 1,75 2,61,8477,9 22, 28 and over 3,47,92 4,, 1,75 2,61,8477,95 22, R14M 28 and over 6,4 1,64 4,, 3,21 4,93,4799 1,6 32, R2M 3 and over 8,5 2,5 4,, 4,4 6,8,349 2,42 15, Figure 1 Pulley groove profile The true profile of the R-type pulley groove can only be produced by plotting the parabolic function associated with the cross section and the number of grooves. Table 16 provides the tip radii dimensions to be used with these generations. Figure 11 illustrates the pulley groove tolerance bands. Table 16 Pulley tip radii Pulley type Number of grooves a r t 8-15,28 R3M 16-3,3 31 and over,4 R5M 1-21,63 22 and over,5 R8M 22-27,9 28 and over,95 R14M 28 and over 1,6 R2M 3 and over 2,42 a the profile band tolerance thru R2 blends into the pulley OD tolerance so that the pulley OD and profile band tolerances do not conflict ISO 25 All Rights Reserved

29 Figure 11 Pulley groove tolerance band Pulley outside diameters Pulleys outside diameters for the standard pulleys are given in Table 17. The relationship of the pulley outside and pitch diameters is illustrated in Figure 12 and the following formula. pitch diameter = No. of grooves x pulley pitch outside diameter = pitch diameter - 2a where a is the value given in Table 1. π ISO 25 All Rights Reserved

30 Figure 12 Pulley dimensions ISO 25 All Rights Reserved

31 ISO 25 All Rights Reserved Table 17 Standard pulley sizes Pulley type R3M R5M R8M R14M R2M Number of grooves Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter Pitch Diameter Outside Diameter ,37 14,32 15,28 16,23 17,19 18,14 19,1 12,61 13,56 14,52 15,47 16,43 17,38 18,34 22,28 23,87 25,46 27,6 28,65 3,24 31,83 21,14 22,73 24,32 25,91 27,5 29,1 3, ,5 21,1 22,92 24,83 26,74 28,65 19,29 2,25 22,16 24,7 25,98 27,89 33,42 35,1 38,2 41,38 44,56 47,75 32,28 33,87 37,5 4,24 43,42 46,6 56,2 61, ,21 71,3 76,39 54,65 59, ,84 7,8 75,13 124,78 129,23 133,69 122,12 126,57 13, ,56 32,47 34,38 36,29 38,2 41,6 42,2 43,93 29,8 31,71 33,62 35,53 37,44 4,3 41,25 43,16 5,93 54,11 57,3 6,48 63,66 68,44 7,3 73,21 49,79 52,97 56,15 59,34 62,52 67,29 68,89 72,7 81,49 86,58 91,67 96,77 11,86 112,5 8,16 85,21 9,3 95,39 1,49 11,67 142,6 151,52 16,43 169,34 178,25 196,8 139,88 148,79 157,68 166,6 175,49 193,28 216,45 229,18 241,92 254,65 28,11 212,13 224,87 237,6 25,33 275, ,48 46,79 47,75 49,66 52,52 57,3 45,7 46,3 46,98 48,89 51,76 56,53 76,39 77,99 79,58 82,76 87,54 89,13 95,49 98,68 75,25 76,84 78,43 81,62 86,39 87,98 94,35 97,53 122,23 142,6 12,86 141,23 213,9 231,73 249,55 267,38 211,11 228,94 246,76 264,59 35,58 331,4 356,51 381,97 31,26 326,72 325,19 377, ,7 66,85 68, ,48 76,39 85,94 95,49 61,31 66,8 67, ,72 75,63 85,18 94,73 13,45 111, ,14 127,32 143,24 159,15 12,31 11, , 126,18 142,1 158,1 162,97 183,35 23,72 229,18 161,6 181,97 22,35 227,81 285,21 33,3 32,86 356,51 41,7 282,41 3,24 318,6 353,71 398,28 47,44 432,9 452, 59,3 572,96 43,12 428,58 447,68 54,98 568, ,4 114,59 124,14 133,69 143,24 152,79 14,28 113,83 123,38 132,92 142,48 152,3 175,7 19,99 26,9 222,82 238,73 254,65 173,93 189,84 25,76 221,67 237,59 235,5 285,21 366, ,83 365, ,11 641,71 748,66 496,32 638,92 745,87 713,1 916, ,52 78,7 912, , ,92 487,55 855,62 962,57 852,82 959, , ,

32 8.2.5 Pulley width The standard nominal pulley width, and the minimum actual pulley width required, b f for flanged pulleys, b' f for unflanged pulleys (see Figure 13), are given in Table 18. Users are advised that the values given for b' f apply also to pulleys with only one flange (see Annex D). Table 18 Standard pulley widths Pulley type Standard nominal Minimum pulley width pulley width Flanged b f Unflanged b' f R3M R5M R8M R14M R2M The minimum unflanged pulley width may be reduced when the alignment of the drive can be controlled, but shall not be less than the minimum flanged pulley width. Figure 13 Minimum pulley width ISO 25 All Rights Reserved

33 9 Type S system 9.1- Type belt dimensions and tolerances Belt tooth dimensions The nominal belt tooth dimensions are the same for single-sided and double-sided belts; they are given in Table 19 and shown in Figure 14. Table 19 Nominal tooth dimensions Belt type Pitch h s h d h t S r bb r a r r Y α a S8M 8 5,3 3,5 5,2 5,2,8,8,686,686 DS8M 8 7,47 3,5 5,2 5,2,8,8,686,686 S14M 14 1,2 5,3 9,1 9,1 1,4 1,4 1,397 1,397 DS14M 14 13,39 5,3 9,1 9,1 1,4 1,4 1,397 1,397 a α is the belt design pitch differential. Figure 14 Tooth dimensions ISO 25 All Rights Reserved

34 9.1.2 Belt widths and tolerances Belt widths and tolerances are given in Table 2. Belt Type S8M DS8M S14M DS14M Table 2 Widths and width tolerances Tolerance on width for belt pitch lengths Up to and Over 84 mm up Nominal belt width including to and including Over 168 mm 84 mm 168 mm ±,8 +,8-1,2 6 ±1,2 4 +,8-1,2 6 ±1,2 8 ±1,6 1 ±1,6 12 ±2,4 +,8-1,2 ±1,2 +1,2-1,6 ±1,2 +1,2-1,6 +1,6-2, +1,6-2, +2,4-2,8 +,8-1,2 +1,2-1,6 ±1,6 +1,2-1,6 ±1,6 ±2, ±2, +2,4-3, Pitch length measurement See Annex A for tolerances and annex B for the relationship between the centre distance and the belt pitch length Measuring fixture (see Figure 15) The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture composed of the following elements. Two pulleys of equal diameter, as specified in Table 21 of the proper belt type and having standard tooth space dimensions. These pulleys should be made to the tolerances shown in Table 21. 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 Means of applying a total measuring force to the moveable pulley ISO 25 All Rights Reserved

35 Means of measuring the centre distance between the two pulleys with the necessary degree of accuracy for centre distance measurement Total measuring force The total measuring force to be applied for measuring belts is given in Table 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 lengths 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. Check double-sided belts on both tooth faces. Total Measuring Force Centre Distance Figure 15 Diagram of fixture for measuring pitch length Belt type Table 21 Belt length measuring pulleys Number of grooves Pitch circumference S8M, DS8M S14M, DS14M 4 56 Radial Axial Outside diameter a runout runout F.I.M. b F.I.M. b 85,28,13,13,25 175,46,25,13,51 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 21 determine the recommended sizes for measuring the belt pitch length. Practically, other sizes of pulleys could be used provided they each have the same number of teeth, and meet the dimensional requirements of Table 21. ISO 25 All Rights Reserved - 3 -

36 Table 22 Total measuring force Forces in Newtons Total measuring force Belt type Belt width, mm S8M, DS8M S14M, DS14M S-type pulleys 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 Generating tool rack Dimensions and tolerances for the generating tool rack for pulleys S8M and S14M are given in Table 23 and Figure ISO 25 All Rights Reserved

37 Table 23 Pulley generating tool rack dimensions Pulley Type Number of grooves P b,12 h r +,5 -, b t +,5 -, r 1 +,5 -, r 2,3 r 3,3 r 4,3 r 5,1 X W a Y S8M 22 and over 8, 2,83 5,2 5,3,75 2,71,4 4,4 5,4 1,13,686, ,611 2,83 4,22 4,74,8,27 5,68,256 Optional S8M ,689 2,83 4,22 4,74,8,29 5,28, ,767 2,83 4,22 4,74,8,32 4,92, ,844 2,83 4,22 4,74,8,35 4,59, ,928 2,83 4,22 4,74,8,38 4,28,342 S14M 28 and over 14, 4,95 9,1 9,28 1,31 4,8,7 7,7 8,84 1,98 1,397 1,397 Optional S14M ,441 4,95 7,5 8,38 1,36,52 9,17, ,577 4,95 7,5 8,38 1,36,56 8,57, ,716 4,95 7,5 8,38 1,36,61 8,3, ,876 4,95 7,5 8,38 1,36,66 7,46,896 NOTE 1: Optional tool rack dimensions represent a refinement of the original patent holder s design. Selection of standard or optional to be agreed between manufacturer and user. Figure 16 Pulley generating tool rack form Pulley groove profile dimensions and tolerances Dimensions and tolerances for the pulley groove profile for S-type pulleys are given in Table 24 and shown in Figure 17. Pulley type Number of grooves Table 24 Pulley groove profile dimensions B g 1 +,1 -, H g ±.3 R 5 ±.1 R 4 ±.1 R 2 +,1 -, R 1 +,1 -, a Y S8M 22 and over 5,2 2,83 4,4,4,75 5,3,686,686 S14M 28 and over 9,1 4,95 7,7,7 1,31 9,28 1,397 1,397 NOTE: The B g dimension is an arc length, not a cord length. ISO 25 All Rights Reserved

38 Figure 17 Pulley groove profile Pulley outside diameters Pulley outside diameters for the standard pulleys are given in Table 25. The relationship of the pulley outside and pitch diameters is illustrated in Figure 18 and the following formula. pitch diameter = No.of grooves x pulley pitch π outside diameter = pitch diameter - 2a where a is the value given in Table ISO 25 All Rights Reserved

39 Number of grooves a Table 25 Standard pulley sizes Pitch diameter 56,2 a 61,12 a 66,21 a 71,3 a 76,39 a 81,49 86,58 91,67 96,77 11,86 112,5 122,23 142,6 162,97 183,35 23,72 229,18 285,21 a 366,69 a 488,92 a S8M Outside diameter 54,65 59,74 64,84 69,93 75,2 8,12 85,21 9,3 95,39 1,49 11,67 12,86 141,23 161,6 181,97 22,35 227,81 283,83 365,32 487,55 Belt type Pitch diameter 124,78 a 129,23 a 133,69 a 142,6 a 151,52 a 16,43 169,34 178,25 196,8 213,9 231,73 249,55 267,38 285,21 33,3 32,86 356,51 41,7 499,11 641,71 748,66 a 855,62 a 962,57 a S14M Outside diameter 121,98 a 126,44 a 13,9 139,81 148,72 157,63 166,55 175,46 193,28 211,11 228,94 246,76 264,59 282,41 3,24 318,6 353,71 398,28 496,32 638,92 745,87 852,82 959,78 Usually not available in all widths -- consult supplier. ISO 25 All Rights Reserved

40 Figure 18 Pulley dimensions Pulley width The standard nominal pulley width, and the actual pulley width required, b f for flanged pulleys, b' f for unflanged pulleys (see Figure 19), are given in Table 26. Users are advised that the values given for b' f apply also to pulleys with only one flange (see annex D). Table 26 Standard pulley widths Standard nominal Minimum pulley width Pulley type pulley width Flanged b f Unflanged b' f S8M S14M The minimum unflanged pulley width may be reduced when the alignment of the drive can be controlled, but shall not be less than the minimum flanged pulley width. Figure 19 Minimum pulley width ISO 25 All Rights Reserved

41 Annex A (normative) Belt pitch lengths and tolerances The belt pitch lengths and tolerances are given in Table A.1. Table A.1 Standard pitch lengths and tolerances Belt Pitch Length Permissible Deviation From Standard Length Over To Single Sided Belts Double Sided Belts ±, ±, ±, ±, ±, ±, ±, ±, ±, ±, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1, ± 1,74 +,8 -,6 +,92 -,69 +1, -,75 +1,2 -,9 +1,32 -,99 +1,44-1,8 +1,64-1,23 +1,74-1,29 +1,84-1,38 +1,96-1,47 +2,8-1,56 +2,16-1,62 +2,24-1,68 +2,32-1,74 +2,4-1,8 +2,52-1,89 +2,64-1,98 +2,76-2,7 +2,88-2,16 +3, -2,25 +3,12-2,34 +3,24-2,43 +3,36-2,52 +3,48-2,61 ISO 25 All Rights Reserved

42 Table A.1 (cont.) Standard pitch lengths and tolerances ± 1, ± 1, ± 1, ± 1,98 +3,6-2,7 +3,72-2,79 +3,84-2,88 +3,96-2,97 NOTE: The permissible deviation from the standard length for double-sided belts is 2 x the plus tolerance and one and 1 1/2 x the minus tolerance of the single-sided belt ISO 25 All Rights Reserved

43 Annex B (normative) Relationship between centre distance and belt pitch length The relationship between centre distance and belt pitch length is given by the following formula: L p = 2C cos + where (D d) 2 + (D - d) 18 L p is the pitch length of belt, in millimetres; C is the centre distance, in millimetres; D is the pitch diameter of large pulley, in millimetres; d is the pitch diameter of small pulley, in millimetres. = sin -1 D d 2C degrees The approximate centre distance C can be found by the following formula: C = K 2 K 2 32( D d) 16 where K = 4 L p - 6,28 (D + d) The exact centre distance can then be determined by trial, using the belt pitch length formula, or by using the centre distance tables available from the belt manufacturers. Figure B-1 ISO 25 All Rights Reserved

44 Annex C (normative) Pulley tolerances C.1 Pitch to pitch tolerances Tolerances on the amount of deviation of pulley pitch between adjacent teeth, and on the cumulative deviation within 9 arc of a pulley, are given in Table C.1. This tolerance applies to the distance between the same point on either the right or left corresponding flanks of adjacent teeth. Table C.1 Pitch to pitch tolerance Allowable deviation of pitch Outside diameter Between any two Summation within d o adjacent teeth a 9 arc a d o 25,4,3,5 25,4 < d o 5,8,3,8 5,8 < d o 11,6,3,11 11,6 < d o 177,8,3,13 177,8 < d o 34,8,3,15 34,8 < d o 58,,3, < d o 762.,3, < d o 116.,3,23 d o > 116.,3,25 a The allowable deviation of pitch is to include the next full tooth past a 9 arc. C.2 Diameter tolerances Table C.2 Tolerances on outside diameter Outside diameter Tolerance d o d o 25,4 +,5/ 25,4 < d o 5,8 +,8/ 5,8 < d o 11,6 +,1/ 11,6 < d o 177,8 +,13/ 177,8 < d o 34,8 +,15/ 34,8 < d o 58, +,18/ 58, < d o 762, +,2/ 762, < d o 1 16, +,23/ d o > 1 16, +,25/ ISO 25 All Rights Reserved

45 C.3 Axial circular runout See Table C.3. Table C.3 Axial circular runout Outside diameter range d o F.I.M. a max. mm mm d o 25,4,5 25,4 < d o 5,8,8 5,8 < d o 11,6,1 11,6 < d o 254,,1 mm per millimetre of outside diameter 254, < d o,25 mm +, 5 mm per millimetre of outside diameter d o > 254, a Full indicator movement C.4 Radial circular runout See Table C.4. Table C.4 Radial circular runout Outside diameter range d o F.I.M. a max. mm mm d o 25,4,5 25,4 < d o 5,8,7 5,8 < d o 11,6,1 11,6 < d o 23,2,13 23,2 < d o,13 mm +, 5 mm per millimetre of outside diameter d o > 23,2 a Full indicator movement C.5 Parallelism Tolerances on pulley parallelism are given in Table C.5. Table C.5 Parallelism Nominal Pulley Width Tolerances b f 4,3 4 < b f 1,4 1 < b f 16,5 16 < b f 22,6 22 < b f 28,7 28 < b f 34,8 ISO 25 All Rights Reserved - 4 -

46 C.6 Cylindricity Tolerances on pulley cylindricity are given in Table C.6. Table C.6 Cylindricity Nominal Pulley Width Tolerances b f 2,2 2 < b f 4,4 4 < b f 8,8 8 < b f 12,12 12 < b f 16,16 16 < b f 34,16mm +,1mm per millimetre Of nominal pulley width b f >16 C.7 Taper The maximum taper will be,1 mm per millimetre of face width provided that the outside diameter remains within the tolerance given in Table C.2. C.8 Quality specifications The quality, finish and balance of pulleys shall comply with the requirements specified in ISO ISO 25 All Rights Reserved

47 Annex D (normative) Flange dimensions The minimum flange height (h) equals the belt tooth height (h t ) plus the pitch line differential (a) for the respective H, R, or S system. The flange dimensions are illustrated in Figure D (max.) 8 (min.) Break sharp corners do + 2h flange outside diameter do Outside diameter Bend diameter do +,5 mm min (do +,2 in. min) h Minimum height of flange Figure D.1 Flange dimensions ISO 25 All Rights Reserved