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Horsepower Rating Synchronous Timing Belt Equations and Calculator
Belt Drive Design and Engineering
Mechanical Gear Design and Engineering
Synchronous Timing Belt Horsepower Rating Equation and Calculator per. ANSI RMA IP24, ISO 5299 and IS 9804.
The horsepower rating formulas for synchronous belts, other than the MLX section, are determined from the following formulas, where the number in parentheses is the belt width in inches.
Use torque rating design formulas for synchronous belts MLX sections:
Torque Rating Synchronous MLX Timing Belt Equation and Calculator
Synchronous Timing Belt Horsepower Rating Calculator Preview
Horsepower rating formulas
XL (0.38) width
HP = K_{z} [ d ( r / 1000 ) ( 0.0916  7.07 x 10^{5} (d r)^{2} ) ]
L (1.00) width
HP = K_{z} [ d ( r / 1000 ) ( 0.436  3.01 x 10^{4} (d r)^{2} ) ]
H (3.00) width
HP = K_{z} [ d ( r / 1000 ) ( 3.73  1.41 x 10^{3} (d r)^{2} ) ]
XH (4.00) width
HP = K_{z} [ d ( r / 1000 ) ( 7.21  4.68 x 10^{3} (d r)^{2} ) ]
XXH (5.00) width
HP = K_{z} [ d ( r / 1000 ) ( 11.4  7.81 x 10^{3} (d r)^{2} ) ]
Where:
HP = the maximum horsepower rating recommended for the specified standard belt width having six or more teeth in mesh and a pulley surface speed of 6500 fpm or less.
d = pitch diameter of smaller pulley in belt mechanism, inch.
r = rpm of fastest shaft
K_{z} = HP rating multiplier (see Table Below). Torque ratings for drives with less than six teeth in mesh must be corrected as shown.
Horsepower ratings for drives with less than six teeth in mesh must be corrected as shown in Table given below
Teeth in Mesh (N)

Factor K_{z}

6 or more

1.00

5

0.80

4

0.60

3

0.40

2

0.20

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
Note:
 Total horsepower ratings are the same for doublesided as for singlesided belts.
 Manufacturers specify percentage of horsepower available for each side of the belt.
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, ISO 5299 and IS 9804.