Classical V-Belts Table 10. Speed Ratio Correction Factors Machinery's Handbook, 31st Edition
2580
Speed Ratio a Range
Speed Ratio a Range
K
K SR
SR
1.00–1.01 1.02–1.04 1.05–1.07 1.08–1.10 1.11–1.14
1.0000 1.0112 1.0226 1.0344 1.0463
1.15–1.20 1.21–1.27 1.28–1.39 1.40–1.64 Over 1.64
1.0586 1.0711 1.0840 1.0972 1.1106
a D p / d p , where D p ( d p ) is the pitch diameter of the large (small) sheave. Table 11. Length Correction Factors
Cross Section
Std. Length Designation
A, AX
B, BX
C, CX
D … … … … … … … … … … … … … … … … … … …
26 31 35 38 42 46 51 55 60 68 75 80 81 85 90 96
0.78 0.82 0.85 0.87 0.89 0.91 0.93 0.95 0.97 1.00 1.02 1.04 1.05 1.07 1.08 … 1.10 1.12 1.13 1.15 …
… …
… … … … … … …
0.80 0.82 0.84 0.86 0.88 0.89 0.91 0.94 0.96 0.98 0.99 … 1.00 1.02 1.03 … 1.05 1.06 1.08 1.10 1.12 1.14 1.15 1.17 1.18 1.22 1.24 1.27
0.80 0.83 0.85 0.87 0.89 0.90 … 0.91 0.92 0.94 … 0.95 0.96 0.98 1.00 1.02 1.04 1.05 1.08 1.07 1.10 1.13 1.15 1.17 1.18 1.20 1.21
97 105 112 120 128 144 158 173 180 195 210 240 270 300 330 360 390 420 480 540 600 660
0.88 0.89 0.91 0.93 0.94 0.95 0.96 0.98 1.00 1.02 1.04 1.06 1.07 1.09 1.10 1.13 1.15 1.17
… … … … … … … … … … … … … … … …
… … … … … … … …
… … … …
… 1.18 Number of Belts: The number of belts required for an application is obtained by dividing the design horsepower by the corrected horsepower rating for one belt. Arc of Contact: Arc of contact on the small sheave may be determined by the formulas. Exact formula: cos C D d 2 2 Arc of Contact (deg) d d 1 = − − a k Approximate formula: C D d 180 60 Arc of Contact (deg) d d = − − c ^ h m where D d = datum diameter of large sheave or flat pulley, inch or mm; d d = datum diameter of small sheave, inch or mm; and, C = distance, inch or mm.
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