1、BRITISH STANDARD BS4548:1987 Specification for Synchronous belt drives for industrial applications UDC 621.852.86.05BS4548:1987 This British Standard, havingbeen prepared under thedirection of the Machinery andComponents Standards Committee, was published underthe authority of the Board ofBSI and co
2、mes into effect on 23 December1987 BSI 08-1999 First published January 1970 First revision December 1987 The following BSI references relate to the work on this standard: Committee reference MCE/10 Draft for comment86/74325DC ISBN 0 580 16177 3 Committees responsible for this British Standard The pr
3、eparation of this British Standard was entrusted by the Machinery and Components Standards Committee (MCE/-) to Technical Committee MCE/10, upon which the following bodies were represented: Agricultural Engineers Association British Gear Association British Rubber Manufacturers Association British C
4、oal Society of Motor Manufacturers and Traders Limited Amendments issued since publication Amd. No. Date of issue CommentsBS4548:1987 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword iii Section 1. General 1.1 Scope 1 1.2 Definitions 1 Section 2. Belts 2.1 Belt designat
5、ion 6 2.2 Dimensions 6 Section 3. Pulleys 3.1 Pulley designation 10 3.2 Groove profile 10 3.3 Pitch-to-pitch tolerances 12 3.4 Pulley dimensions 12 3.5 Material 15 3.6 Surface finish 15 3.7 Parallelism 15 3.8 Taper of outside diameter 15 3.9 Axial and radial run-out 15 3.10 Balancing 15 Appendix A M
6、easurement of the pitch length of a synchronous belt 18 Appendix B Procedure for checking pulley groove profile 18 Appendix C Determination of axial and radial run-out 18 Appendix D Recommendations for the use of idlers 21 Figure 1 Nominal belt tooth dimensions 6 Figure 2 Pulley groove profile 10 Fi
7、gure 3 Unflanged, flanged and single flanged pulleys indicating position of minimum unflanged width 14 Figure 4 Dimensions of flange for flanged and single flanged pulleys 15 Figure 5 Limiting speeds above which pulleys require dynamic balancing 17 Figure 6 Length measuring fixture 18 Figure 7 Clear
8、ance between measuring pulley and belt 18 Figure 8 Measurement of axial run-out 20 Figure 9 Measurement of radial run-out 20 Figure 10 Inside and outside idler pulleys 21 Table 1 Terms and definitions 2 Table 2 Nominal belt tooth dimensions 7 Table 3 Pitch lengths and tolerances 8 Table 4 Heights an
9、d widths of belts 9 Table 5 Pulley groove tolerances 11 Table 6 Values of upper reference depth for pulley groove tolerances 12 Table 7 Pitch and summation of pitch tolerance of pulleys 12 Table 8 Pulley diameters 13 Table 9 Tolerance on pulley pitch and diameter 14 Table 10 Flange dimensions 15 Tab
10、le 11 Surface finish of synchronous pulley grooves 15BS4548:1987 ii BSI 08-1999 Page Table 12 Axial run-out 16 Table 13 Radial run-out 16 Table 14 Belt length measuring fixture pulleys 19 Table 15 Total force for pitch length measurement 19 Publications referred to Inside back coverBS4548:1987 BSI 0
11、8-1999 iii Foreword This British Standard has been prepared under the direction of the Machinery and Components Standards Committee. It specifies the dimensional and other features of synchronous belt drives and pulleys that are in the most general use for a wide range of industrial applications. It
12、 is a revision of BS4548:1970 which is withdrawn. Racks used for generating tooth forms on the pulleys are of specific interest to pulley manufacturers rather than designers or users of the drive systems. It has been convenient therefore to assemble the requirements for racks in a separate standard
13、BS6889. In view of the widespread use of synchronous belt drives in many countries, particular account has been taken of discussion and standards published by the International Organization for Standardization (ISO) and specifically ISO5294 and ISO5296. Synchronous belt drives are used for mechanica
14、l power transmission where positive indexing or synchronous speeds are required. The serviceability of the drives depends to a degree upon satisfactory choice of dimensions and proper installation practice. Methods for measuring belt pitch length, determining axial and radial run-out and checking th
15、e pulley groove profile are given in Appendix A, Appendix B and Appendix C. Appendix D gives recommendations for the use of idlers. The terminology used generally follows that adopted in ISO specifications for synchronous drive systems. However, the term “tooth space” is used in the International St
16、andards, but the synonymous term “groove” has been retained in this standard to conform to established UK practice. This standard does not apply to automotive synchronous belt drives which are specified in BS AU218. A British Standard does not purport to include all the necessary provisions of a con
17、tract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, pages1to22, an inside back cover
18、and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS4548:1987 BSI 08-1999 1 Section 1. General 1.1 Scope This British Standard specifies requirements for sync
19、hronous belt drives and pulleys of the types designated by the pitch codes XL, L, H, XH and XXH and used for industrial applications. Appendix D given recommendations for the use of idler pulleys. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 1.
20、2 Definitions For the purposes of this British Standard, the definitions given in Table 1 apply. Where appropriate, diagrams are included to further define specific features. BS 4548:1987 2 BSI 08-1999 Table 1 Terms and definitions Term Symbol Definition Term relating to drives using synchronous bel
21、ts synchronous belt drive a A system composed of a synchronous belt and two or more synchronous pulleys. Synchronized motion and/or power is transmitted through the engagement of teeth on the belt with grooves on the pulleys Terms relating to synchronous belts synchronous belt A belt, the cross sect
22、ion of which is in the general form of a rectangle, but with transverse teeth extending from the lower base at regularly spaced intervals belt pitch P b The linear distance between the axes of two consecutive teeth in a section of belt loaded to the prescribed measuring force pitch length L p The le
23、ngth of the pitch line of a belt pitch line Any circumferential line in the belt that keeps the same length when the belt is bent perpendicularly to its base a This belt drive has been known in the past by various names such as timing belt drive, positive belt drive, or gear belt drive.BS 4548:1987
24、BSI 08-1999 3 Table 1 Terms and definitions Term Symbol Definition width b s The transverse dimension of the belt that can be used to transmit power height h s The total height of the belt Terms relating to synchronous belt teeth tooth height h t The distance between the tip line and the root line t
25、ooth angle 2 The included angle between the flanks of the belt toothBS 4548:1987 4 BSI 08-1999 Table 1 Terms and definitions Term Symbol Definition Terms relating to synchronous pulleys outside diameter d o The diameter of the tip circle pitch diameter d The diameter of the pitch circle, i.e.the out
26、side diameter plus twice the pitch line differential pitch line differential a The radial distance between the pitch circle and tip circleBS 4548:1987 BSI 08-1999 5 Table 1 Terms and definitions Term Symbol Definition pitch a p b The length of the arc on the pitch circle contained between two consec
27、utive corresponding profiles groove root radius r b The radius of a curve connecting the groove flank with the root diameter groove root top radius r t The radius of a curve connecting the groove flank with the outside diameter top curvature The area from the outside diameter to the upper reference
28、depth, i.e.start of the flank b flank The distance between the upper and lower reference depths b bottom curvature The area from the lower reference depth to the bottom of the groove profile b lower reference depth The point of tangency of the belt tooth bottom radius and the straight-sided belt too
29、th flank b upper reference depth The point dividing the profile into an area generated by the rack top radius and an area generated by the cutter flank b a The pitch of the pulley, considered as a segment of a rack, corresponds with that of the belt. b See Figure 2.BS4548:1987 6 BSI 08-1999 Section
30、2. Belts 2.1 Belt designation The belt for synchronous drives for industrial applications is characterized by pitch length, width and a pitch code (i.e.type designation) that defines the pitch and the dimensions of the tooth profile. The belt shall be designated by a series of numbers and letters. T
31、he first set of numbers indicates the pitch length, the letters (pitch code) indicate the belt section and the second set of numbers indicates the width. 2.2 Dimensions 2.2.1 Nominal belt tooth dimensions The nominal belt tooth dimensions shall be as given in Table 2 and shown in Figure 1. 2.2.2 Pit
32、ch lengths and tolerances The pitch length shall be measured in accordance with Appendix A, and the pitch length tolerances shall be as given in Table 3. 2.2.3 Belt heights and widths The nominal height, belt width and associated tolerances shall be chosen from the values in Table 4. Figure 1 Nomina
33、l belt tooth dimensionsBS4548:1987 BSI 08-1999 7 Table 2 Nominal belt tooth dimensions Belt pitch code Belt pitch P b 2 S h t r r r a XL L H XH XXH mm 5.08 9.525 12.700 22.225 31.750 in 0.200 0.375 0.500 0.875 1.250 degrees 50 40 40 40 40 mm 2.57 4.65 6.12 12.57 19.05 in 0.101 0.183 0.241 0.495 0.75
34、0 mm 1.27 1.91 2.29 6.35 9.53 in 0.050 0.075 0.090 0.250 0.375 mm 0.38 0.51 1.02 1.57 2.29 in 0.015 0.020 0.040 0.062 0.090 mm 0.38 0.51 1.02 1.19 1.52 in 0.015 0.020 0.040 0.047 0.060BS4548:1987 8 BSI 08-1999 Table 3 Pitch lengths and tolerances Belt length designation Pitch length Pitch length tol
35、erance Number of teeth XL L H XH XXH 60 70 80 90 100 mm 152.40 177.80 203.20 228.60 254.00 in 6.000 7.000 8.000 9.000 10.000 mm 0.41 0.41 0.41 0.41 0.41 in 0.016 0.016 0.016 0.016 0.016 30 35 40 45 50 110 120 124 130 140 279.40 304.80 314.33 330.20 355.60 11.000 12.000 12.375 13.000 14.000 0.46 0.46
36、 0.46 0.46 0.46 0.018 0.018 0.018 0.018 0.018 55 60 65 70 33 150 160 170 180 187 381.00 406.40 431.80 457.20 476.25 15.000 16.000 17.000 18.000 18.750 0.46 0.51 0.51 0.51 0.51 0.018 0.020 0.020 0.020 0.020 75 80 85 90 40 50 190 200 210 220 225 482.60 508.00 533.40 558.80 571.50 19.000 20.000 21.000
37、22.000 22.500 0.51 0.51 0.61 0.61 0.61 0.020 0.020 0.024 0.024 0.024 95 100 105 110 56 60 230 240 250 255 260 584.20 609.60 635.00 647.70 660.40 23.000 24.000 25.000 25.500 26.000 0.61 0.61 0.61 0.61 0.61 0.024 0.024 0.024 0.024 0.024 115 120 125 130 64 68 48 270 285 300 322 330 685.80 723.90 762.00
38、 819.15 838.20 27.000 28.500 30.000 32.250 33.000 0.61 0.61 0.61 0.66 0.66 0.024 0.024 0.024 0.026 0.026 72 76 80 86 54 60 66 345 360 367 390 420 876.30 914.40 933.45 990.60 1066.80 34.500 36.000 36.750 39.000 42.000 0.66 0.66 0.66 0.66 0.76 0.026 0.026 0.026 0.026 0.030 92 98 104 112 72 78 84 450 4
39、80 507 510 540 1143.00 1289.05 1289.50 1295.40 1371.60 45.000 48.000 50.750 51.000 54.000 0.76 0.76 0.81 0.81 0.81 0.030 0.030 0.032 0.032 0.032 120 128 136 144 90 96 102 108 58 560 570 600 630 660 1422.40 1447.80 1524.00 1600.20 1676.40 56.000 57.000 60.000 63.000 66.000 0.81 0.81 0.81 0.86 0.86 0.
40、032 0.032 0.032 0.034 0.034 160 114 120 126 132 64 72 700 750 770 800 840 1778.00 1905.00 1955.80 2032.00 2133.60 70.000 75.000 77.000 80.000 84.000 0.86 0.91 0.91 0.91 0.97 0.034 0.036 0.036 0.036 0.038 140 150 160 80 88 96 56 64 850 900 980 1000 1100 2159.00 2286.00 2489.20 2540.00 2794.00 85.000
41、90.000 98.000 100.000 110.000 0.97 0.97 1.02 1.02 1.07 0.038 0.038 0.040 0.040 0.042 170 180 200 220 112 72 80 1120 1200 1250 1260 1400 2844.80 2048.00 3175.00 3200.40 3556.00 112.000 120.000 125.000 126.000 140.000 1.12 1.12 1.17 1.17 1.22 0.044 0.044 0.046 0.046 0.048 250 280 128 144 160 96 112 15
42、40 1600 1700 1750 1800 3911.60 4064.00 4318.00 4445.00 4572.00 154.000 160.000 170.000 175.000 180.000 1.32 1.32 1.37 1.42 1.42 0.052 0.052 0.054 0.056 0.056 340 176 200 128 144BS4548:1987 BSI 08-1999 9 Table 4 Heights and widths of belts Pitch code Nominal height h s Width b s Tolerance on width fo
43、r belt pitch lengths Designation Dimensions Up to and including 838.20mm (33.000in) Over838.20mm (33.000in) up to and including 1676.40 mm (66.000in) Over1676.40mm (66.000in) XL mm 2.3 in 0.09 025 031 037 mm 6.4 7.9 9.5 in 0.25 0.31 0.37 mm + 0.5 0.8 in + 0.02 0.03 mm in mm in L 3.6 0.14 050 075 100
44、 12.7 19.1 25.4 0.50 0.75 1.00 + 0.8 0.8 + 0.03 0.03 + 0.8 1.3 + 0.03 0.05 H 4.3 0.17 075 100 150 19.1 25.4 38.1 0.75 1.00 1.50 + 0.8 0.8 + 0.03 0.03 + 0.8 1.3 + 0.03 0.05 + 0.8 1.3 + 0.03 0.05 200 50.8 200 + 0.8 1.3 + 0.03 0.05 + 1.3 1.3 + 0.05 0.05 + 1.3 1.5 + 0.05 0.06 300 76.2 3.00 + 1.3 1.5 + 0
45、.05 0.06 + 1.5 1.5 + 0.06 0.06 + 1.5 2.0 + 0.06 0.08 XH 11.2 0.44 200 300 400 50.8 76.2 101.6 2.00 3.00 4.00 + 4.8 4.8 + 0.19 0.19 + 4.8 4.8 + 0.19 0.19 XXH 15.7 0.62 200 300 400 500 50.8 76.2 101.6 127.0 2.00 3.00 4.00 5.00 + 4.8 4.8 + 0.19 0.19BS4548:1987 10 BSI 08-1999 Section 3. Pulleys 3.1 Pull
46、ey designation The pulley for synchronous drives for industrial use is characterized by the number of grooves, the pitch code which defines the groove profile, and the width. It is identified, as is the belt, by a series of numbers and letters. The first set of numbers indicates the number of groove
47、s, the letters indicate the groove profile and the second set of numbers indicates the width. 3.2 Groove profile 3.2.1 General Pulleys are characterized by the involute contour of the groove flanks. This contour shown in Figure 2 is different in detail for each pulley diameter. There is a practical
48、difficulty in giving size specifications for the contour relative to each diameter. However the profile is determined by the detailed geometry and dimensions of the rack used to generate the involute teeth on a pulley. The dimensions of such racks are given in BS6889. 3.2.2 Master profile The groove profile is generated by the nominal pulley generating tool rack (of a form specified in BS6889) at a specific number of grooves and nominal pulley outside diameter. T
