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VBelt Classical Speed to Horsepower Formulas and Calculator for Cross Sections
Belt Drive Design and Engineering
Mechanical Gear Design and Engineering
VBelt Classical Speed to Horsepower Ratings Formulas and Calculator for Cross Sections
Cross Section Design Selection: Use the chart given below to determine if the Vbelt cross section 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, the possibilities in both areas should be investigated. Special circumstances (such as space limitations) may lead to a choice of belt cross section different from that indicated in the chart.
Design HP = Basic Horsepower Rating x Service Factor
Basic Horsepower Rating Formulas
VBelt Cross Section "A"
HP = d_{p} r_{k} [ 1.004  1.652 / d_{p}  1.5747 x 10^{4} ( d_{p} r )^{2}  0.2126 log( d_{p} r ) ] + 1.652 r ( 1  1 / K_{SR} )
VBelt Cross Section "AX"
HP = d_{p} r_{k} [ 1.462  2.239 / d_{p}  2.198 x 10^{4} ( d_{p} r )^{2}  0.4238 log( d_{p} r ) ] + 2.239 r ( 1  1 / K_{SR} )
VBelt Cross Section "B"
HP = d_{p} r_{k} [ 1.769  4.372 / d_{p}  3.081 x 10^{4} ( d_{p} r )^{2}  0.3658 log( d_{p} r ) ] + 4.372 r ( 1  1 / K_{SR} )
VBelt Cross Section "BX"
HP = d_{p} r_{k} [ 2.051  3.532 / d_{p}  3.097 x 10^{4} ( d_{p} r )^{2}  0.5735 log( d_{p} r ) ] + 3.532 r ( 1  1 / K_{SR} )
VBelt Cross Section "C"
HP = d_{p} r_{k} [ 3.325  12.07 / d_{p}  5.828 x 10^{4} ( d_{p} r )^{2}  0.6886 log( d_{p} r ) ] + 12.07 r ( 1  1 / K_{SR} )
VBelt Cross Section "CX"
HP = d_{p} r_{k} [ 3.272  6.655 / d_{p}  5.298 x 10^{4} ( d_{p} r )^{2}  0.8637 log( d_{p} r ) ] + 6.655 r ( 1  1 / K_{SR} )
VBelt Cross Section "D"
HP = d_{p} r_{k} [ 7.160  43.21 / d_{p}  1.384 x 10^{4} ( d_{p} r )^{2}  1.454 log( d_{p} r ) ] + 43.21 r ( 1  1 / K_{SR} )
Where:
dp = pitch diameter of small sheave, in.
r = rpm of the faster shaft.
r_{k} = r / 1000
K_{SR} = speed ratio factor given in the accompanying Table below.
Speed Ratio Range = D_{p} / d_{p}
Where:
D_{p} = Pitch of Large Sheave
d_{p} = Pitch of Small Sheave
Speed Ratio Range

K_{SR}

1.00  1.01

1.0000

1.02  1.04

1.0112

1.05  1.07

1.0226

1.08  1.10

1.0344

1.11  1.14

1.0463

1.15  1.20

1.0586

1.21  1.27

1.0711

1.28  1.39

1.0840

1.40  1.64

1.0972

> 1.64

1.1106

FPM to RPM Equation:
r = s / ( π d )
RPM to FPM Equation:
s = r π d
Where:
r = rpm
s = ft / min
d = diameter of pulley in ft
Related:
 Synchronous Timing Belt Tooth Section Dimensions Table per ANSI / RMA IP24
 Synchronous Timing Belt Pulley Dimensions Table per ANSI / RMA IP24
 Synchronous Timing Belt Lengths and Tolerances per. ANSI RMA IP24 Table
 Service Factors Synchronous Timing Belts
 Synchronous Timing Belt Standard Widths and Tolerances Table
 Synchronous Belt Standard Pulley Diameters ANSI/RMA IP24 Table
 Timing Belt Pulley Mechanical Tolerances per. ANSI RMA IP24
References:
ANSI / RMA IP24