Machinery's Handbook, 31st Edition
2592 V-Ribbed Belts Horsepower Ratings: The horsepower ratings for light duty V-belts can be calculated from the following formulas: . . . . . . . . . HP r r d r d HP r r d r d HP r r d r d 02164 0 2324 0 0001396 04666 0 7231 0 0002286 07748 1 727 0 0003641 3L 4L 5L 2 3 2 3 2 3 = − − = − − = − − a a a k k k 0.91 0.09 0.09 0.09 0.91 0.91 where d = d 0 − 2 a ; d 0 = effective outside diameter of small sheave, in.; r = rpm of the faster shaft divided by 1000. The corrected horsepower rating is obtained by dividing the horsepower rating by the combined correction factor (Table 24), which accounts for drive geometry and service factor requirements. Table 24. Combined Correction Factors
Speed Ratio
Type of Driven Unit
Less than 1.5
1.5 and Over
Fans and blowers
1.0 1.1 1.1 1.2 1.2 1.3 1.4 1.4
0.9 1.0 1.0 1.1 1.1 1.2 1.3 1.3
Domestic laundry machines Centrifugal pumps Rotary compressors Machine tools Reciprocating pumps Reciprocating compressors Generators
Woodworking machines 1.3 V-Ribbed Belts ANSI/RMA IP-26.— V-ribbed belts are a cross between flat belts and V-belts. The belt is basically flat with V-shaped ribs projecting from the bottom, which guide the belt and provide greater stability than that found in a flat belt. The ribs operate in grooved sheaves. 1.4 V-ribbed belts do not have the wedging action of a V-belt and thus operate at higher ten sions. This design provides excellent performance in high-speed and serpentine applica tions, and in drives that utilize small diameter sheaves. The V-ribbed belt comes in five cross sections: H, J, K, L, and M, specified by effective length, cross section and number of ribs. Belt Cross Sections: Nominal dimensions of the five cross sections are given in Table 25. Table 25. Nominal Dimensions of V-Ribbed Belt Cross Sections ANSI/RMA IP-26, 1977 b b S g b b = N r S g , where N r = number of ribs and S g is sheave groove spacing h b Cross Section h b S g Standard Number of Ribs H 0.12 0.063 … J 0.16 0.092 4, 6, 10, 16, 20 K 0.24 0.140 … L 0.38 0.185 6, 8, 10, 12, 14, 16, 18, 20 M 0.66 0.370 6, 8, 10, 12, 14, 16, 18, 20 All dimensions in inches.
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