Machinery's Handbook, 31st Edition
2572 Narrow V-Belts Table 3. Standard Sheave Outside Diameters ANSI/RMA IP-22, 1983 3V 5V 8V Nom Min Max Nom Min Max Nom Min Max 2.65 2.638 2.680 7.10 7.087 7.200 12.50 12.402 12.600 2.80 2.795 2.840 7.50 7.480 7.600 13.20 13.189 13.400 3.00 2.953 3.000 8.00 7.874 8.000 14.00 13.976 14.200 3.15 3.150 3.200 8.50 8.346 8.480 15.00 14.764 15.000 3.35 3.346 3.400 9.00 8.819 8.960 16.00 15.748 16.000 3.55 3.543 3.600 9.25 9.291 9.440 17.00 16.732 17.000 3.65 3.642 3.700 9.75 9.567 9.720 18.00 17.717 18.000 4.00 3.937 4.000 10.00 9.843 10.000 19.00 18.701 19.000 4.12 4.055 4.120 10.30 10.157 10.320 20.00 19.685 20.000 4.50 4.409 4.480 10.60 10.433 10.600 21.20 20.866 21.200 4.75 4.646 4.720 10.90 10.709 10.880 22.40 22.047 22.400 5.00 4.921 5.000 11.20 11.024 11.200 23.60 23.622 24.000 5.30 5.197 5.280 11.80 11.811 12.000 24.80 24.803 25.200 5.60 5.512 5.600 12.50 12.402 12.600 30.00 29.528 30.000 6.00 5.906 6.000 13.20 13.189 13.400 31.50 31.496 32.000 6.30 6.299 6.400 14.00 13.976 14.200 35.50 35.433 36.000 6.50 6.496 6.600 15.00 14.764 15.000 40.00 39.370 40.000 6.90 6.890 7.000 16.00 15.748 16.000 44.50 44.094 44.800 8.00 7.874 8.000 18.70 18.701 19.000 50.00 49.213 50.000 10.00 9.843 10.000 20.00 19.685 20.000 52.00 51.969 52.800 10.60 10.433 10.600 21.20 20.866 21.200 63.00 62.992 64.000 12.50 12.402 12.600 23.60 23.622 24.000 71.00 70.866 72.000 14.00 13.976 14.200 25.00 24.803 25.200 79.00 78.740 80.000 16.00 15.748 16.000 28.00 27.953 28.400 99.00 98.425 100.000 19.00 18.701 19.000 31.50 31.496 32.000 … … … 20.00 19.685 20.000 37.50 37.402 38.000 … … … 25.00 24.803 25.200 40.00 39.370 40.000 … … … 31.50 31.496 32.000 44.50 44.094 44.800 … … … 33.50 33.465 34.000 50.00 49.213 50.000 … … … … … … 63.00 62.992 64.000 … … … … … … 71.00 70.866 72.000 … … … All dimensions in inches. The nominal diameters were selected from R40 and R80 preferred numbers (see page 687). Minimum Sheave Size: The recommended minimum sheave size depends on the rpm of the faster shaft. Minimum sheave diameters for each belt cross section are listed in Table 3. Cross Section Selection: The chart (Fig. 2, on page 2573) is a guide to the V-belt cross section to use for any combination of design horsepower and speed of the faster shaft. When the intersection of the design horsepower and speed of the faster shaft falls near a line between two areas on the chart, it is advisable to investigate the possibilities in both areas. Special circumstances (such as space limitations) may lead to a choice of belt cross section different from that indicated in the chart. Horsepower Ratings: The horsepower ratings of narrow V-belts can be calculated using the following formula: log drK d Kdr K dr K K r HP p p p p SR 1 3 2 4 2 = − − − + ^ ^ h h < F where d p = the pitch diameter of the small sheave, in.; r = rpm of the faster shaft divided by 1000; K SR , speed ratio correction factor (Table 4), and K 1 , K 2 , K 3 , and K 4 , cross section parameters, are listed in the accompanying Table 5. This formula gives the basic horse power rating, corrected for the speed ratio. To obtain the horsepower per belt for an arc of contact other than 180 ° and for belts shorter or longer than average length, multiply the horsepower obtained from this formula by the length correction factor (Table 7) and the arc of contact correction factor (Table 6).
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