Machinery's Handbook, 31st Edition
Variable Speed Belts 2597 D o = effective outside diameter of large sheave, inch; d o = effective outside diameter of small sheave, inch; and, C = center distance, inch. Table 30. Speed Ratio Correction Factors Speed Ratio a K SR 1.00 to and incl. 1.10 1.0000 Over 1.01 to and incl. 1.04 1.0136 Over 1.04 to and incl. 1.08 1.0276 Over 1.08 to and incl. 1.12 1.0419 Over 1.12 to and incl. 1.18 1.0567 Over 1.18 to and incl. 1.24 1.0719 Over 1.24 to and incl. 1.34 1.0875 Over 1.34 to and incl. 1.51 1.1036 Over 1.51 to and incl. 1.99 1.1202 Over 1.99 1.1373 a D p / d p , where D p ( d p ) is the pitch diameter of the large (small) sheave. Variable Speed Belts ANSI/ RMA IP-25.— For drives that require more speed variation than can be obtained with conventional industrial V-belts, standard-line variable-speed drives are available. These drives use special wide, thin belts. Package units of standard- line variable-speed belts and sheaves, combined with the motor and output gearbox, are available in ranges from approximately 1 ⁄ 2 through 100 horsepower. The speed ranges of variable-speed drives can be much greater than those drives using classical V-belts. Speed ranges up to 10:1 can be obtained on lower horsepower units. This section covers 12 variable speed belt cross sections and sheave groove sizes de- signed 1422V, 1922V, 2322V, 1926V, 2926V, 3226V, 2530V, 3230V, 4430V, 4036V, 4436V, and 4836V. The industry supplies many other sizes that are not listed in this section. Belt Cross Sections and Lengths: Nominal dimensions of the 12 cross sections are given in Table 31, and lengths in Table 32. Table 31. Normal Variable-Speed Belt Dimensions ANSI/RMA IP-25, 1982 b b
h b
Cross Section
h b / b b Cross Section
h b / b b 0.38 0.31 0.25 0.28 0.26 0.25
b b
b b
h b
h b
1422V 0.88 1922V 1.19 2322V 1.44 1926V 1.19 2926V 1.81 3226V 2.0
0.31 0.38 0.44 0.44 0.50 0.53
0.35 0.32 0.31 0.37 0.28 0.27
2530V 1.56 3230V 2.00 4430V 2.75 4036V 2.50 4436V 2.75 4836V 3.00
0.59 0.62 0.69 0.69 0.72 0.75
All dimensions in inches.
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