Horsepower and Torque Rating Formulas

TORQUE RATINGS

It is customary to use torque load requirements rather than horsepower load when designing drives using the small pitch MXL section belts. Torque ratings are shown in Table 18 for each standard belt width. Since these belts operate on small diameters resulting in relatively low belt speeds, torque is essentially constant for all rpms. These ratings are based on the adjacent formulas:

TEETH IN MESH FACTOR

The horsepower or torque ratings from Tables 18, 19, and 20 must be corrected for excessive tooth loading if there are less than 6 teeth in mesh between the belt and the pulley. Determine the proper factor Kz from the following Table 15 to correct for teeth in mesh.

NOMINAL TOOTH DIMENSIONS

Table 9 and Figure 7 show the nominal tooth dimensions for each of the standard belt sections. The tooth dimensions for double-sided belts are identical to those of a single-sided belt.

HORSEPOWER RATINGS

Horsepower ratings are used for belt sections MXL, XL and L. These ratings are for the widest standard belt*. To obtain the horsepower rating for other belt widths, multiply the horsepower rating by the appropriate factor shown in Table 16. The horsepower ratings (Tables 18, 19, and 20) are based on the following formulas:

Torgue Rating Formulas
BELT SELECTION BELT WIDTH, INCHES FORMULA
MXL (0.080) 0.12 Qr = d (1.13 - 1.38 X 103 d2)
0.19 Qr = d (1.88 - 2.30 X 103 d2)
0.25 Qr = d (2.63 - 3.21 X 103 d2)

where:
Qr = The maximum torque rating (Ibf-inches) for a belt of specified width having six or more teeth in mesh and a pulley surface speed of 6500 feet/minute or less. Torque ratings for drives with less than six teeth in mesh must be corrected as shown in Table 15, Teeth in Mesh Factor.
d = Pitch diameter of smaller pulley, inches.

Teeth in Mesh Factor
TEETH IN MESH FACTOR KZ
6 or more 1.00
5 0.80
4 0.60
3 0.40
2 0.20

The teeth in mesh may be calculated with the following formula:
Teeth in Mesh = [0.5 – (D-d/6C)]z1
where
D = pitch diameter, large pulley, inches
d = pitch diameter, small pulley, inches
C = center distance between shafts,inches
z1 = number of grooves in small pulley

*Total horsepower ratings for double-sided belts are the same as single-sided belts. Contact York Engineering for percent of horsepower available for each side of the belt.

Table 16 Belt Width Factor
BELT SELECTION BELT WIDTH (INCHES)
0.12 0.19 0.25 0.38 0.50 0.75 1.00
MXL (0.080) 0.43 0.73 1.00
XL (0.200) 0.62 1.00
L (0.375) 0.45 0.72 1.00
Table 18 Torque rating for MXL section (0.080 inch pitch)
BELT WIDTH, INCHES RATED TORQUE (IBF-INCH) FOR SMALL PULLEY
(NUMBER OF GROOVES AND PITCH DIAMETER, INCHES)
10MXL
0.255		 12MXL
0.306		 14MXL
0.357		 16MXL
0.407		 18MXL
0.458		 20MXL
0.509		 22MXL
0.560		 24MXL
0.611		 28MXL
0.713		 30MXL
0.764
0.12 0.29 0.35 0.40 0.46 0.52 0.57 0.63 0.69 0.81 0.86
0.19 0.48 0.58 0.67 0.77 0.86 0.96 1.05 1.15 1.34 1.44
0.25 0.67 0.80 0.94 1.07 1.20 1.34 1.47 1.61 1.87 2.01
Table 19 Horsepower rating for .38 inch wide XL Section Belt (0.200 inch pitch)
RPM of Faster Shaft RATED HORSEPOWER FOR SMALL PULLEY (NUMBER OF GROOVES AND PITCH DIAMETER)
10XL 12XL 14XL 16XL 18XL 20XL 22XL 24XL 28XL 30XL
0.637 0.764 0.891 1.019 1.146 1.273 1.401 1.528 1.783 1.910
950 0.055 0.066 0.077 0.089 0.10 0.11 0.12 0.13 0.15 0.17
1160 0.068 0.081 0.095 0.11 0.12 0.14 0.15 0.16 0.19 0.20
1425 0.083 0.10 0.12 0.13 0.15 0.17 0.18 0.20 0.23 0.25
1750 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.28 0.30
2850 0.17 0.20 0.23 0.26 0.30 0.33 0.36 0.39 0.46 0.49
3450 0.20 0.24 0.28 0.32 0.36 0.40 0.43 0.47 0.55 0.58
100 0.006 0.007 0.008 0.009 0.010 0.012 0.013 0.014 0.016 0.017
200 0.012 0.014 0.016 0.019 0.021 0.023 0.026 0.028 0.033 0.035
300 0.018 0.021 0.024 0.028 0.031 0.035 0.038 0.042 0.049 0.052
400 0.023 0.028 0.033 0.037 0.042 0.047 0.051 0.056 0.065 0.070
500 0.029 0.035 0.041 0.047 0.052 0.058 0.064 0.070 0.082 0.087
600 0.035 0.042 0.049 0.056 0.063 0.070 0.077 0.084 0.098 0.10
700 0.041 0.049 0.057 0.065 0.073 0.082 0.090 0.098 0.11 0.12
800 0.047 0.056 0.065 0.075 0.084 0.093 0.10 0.11 0.13 0.14
900 0.053 0.063 0.073 0.084 0.094 0.10 0.12 0.13 0.15 0.16
1000 0.058 0.070 0.082 0.093 0.10 0.12 0.13 0.14 0.16 0.17
1100 0.064 0.077 0.090 0.10 0.12 0.13 0.14 0.15 0.18 0.19
1200 0.070 0.084 0.098 0.11 0.13 0.14 0.15 0.17 0.20 0.21
1300 0.076 0.091 0.11 0.12 0.14 0.05 0.17 0.18 0.21 0.23
1400 0.082 0.098 0.11 0.13 0.15 0.16 0.18 0.20 0.23 0.24
1500 0.070 0.10 0.12 0.14 0.16 0.17 0.19 0.21 0.24 0.26
1600 0.070 0.11 0.13 0.15 0.17 0.19 0.20 0.22 0.26 0.28
1700 0.070 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.28 0.30
1800 0.070 0.13 0.15 0.17 0.19 0.21 0.23 0.25 0.29 0.31
0.11 0.12 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11
2200 0.13 0.15 0.18 0.20 0.23 0.25 0.28 0.31 0.36 0.38
2400 0.14 0.17 0.20 0.22 0.25 0.28 0.31 0.33 0.39 0.41
2600 0.15 0.18 0.21 0.24 0.27 0.30 0.33 0.36 0.42 0.45
2800 0.16 0.20 0.23 0.26 0.29 0.32 0.36 0.39 0.45 0.48
3000 0.17 0.21 0.24 0.28 0.31 0.35 0.38 0.41 0.48 0.51
3200 0.19 0.22 0.26 0.30 0.33 0.37 0.40 0.44 0.51 0.54
3400 0.20 0.24 0.28 0.31 0.35 0.39 0.43 0.47 0.54 0.58
3600 0.21 0.25 0.29 0.33 0.37 0.41 0.45 0.49 1.57 0.61
3800 0.22 0.26 0.31 0.35 0.39 0.44 0.48 0.52 0.60 0.64
4000 0.23 0.28 0.32 0.37 0.41 0.46 0.50 0.54 0.63 0.67
4200 0.24 0.29 0.34 0.39 0.43 0.48 0.52 0.57 0.66 0.70
4400 0.26 0.31 0.35 0.40 0.45 0.50 0.55 0.59 0.68 0.73
4600 0.27 0.32 0.37 0.42 0.47 0.52 0.57 0.62 0.71 0.76
4800 0.28 0.33 0.39 0.44 0.49 0.54 0.59 0.64 0.74 0.79
5000 0.29 0.35 0.40 0.46 0.51 0.56 0.62 0.67 0.77 0.81
5500 0.50 0.56 0.62 0.67 0.73 0.83 0.88
6000 0.54 0.61 0.67 0.73 0.79 0.89 0.94
6500 0.59 0.65 0.72 0.78 0.84 0.95 1.00
7000 0.63 0.70 0.77 0.83 0.89 1.01 1.06
7500 0.67 0.74 0.81 0.88 0.94 1.06 1.10
8000 0.79 0.86 0.93 0.99 1.10 1.15
8500 0.83 0.90 0.97 1.03 1.14 1.18
9000 0.87 0.94 1.01 1.08 1.18 1.22
9500 0.91 0.98 1.05 1.11 1.21 1.24
10000 0.94 1.02 1.09 1.15 1.23 1.26
 This pulley and RPM can be used only if a corresponding reduction in belt service life is allowable.
Table 20 Horsepower rating for 1.00 inch wide L section belt (0.375 inch pitch)
RPM of Faster Shaft RATED HORSEPOWER FOR SMALL PULLEY (NUMBER OF GROOVES AND PITCH DIAMETER)
10L 12L 14L 15L 18L 20L 22L 24L 26L 28L 30L 32L 36L 40L 44L 48L
1.194 1.432 1.671 1.910 2.149 2.387 2.628 2.865 3.104 3.342 3.581 3.820 4.297 4.775 5.252 5.730
725 0.38 0.45 0.53 0.60 0.68 0.75 0.83 0.90 0.98 1.05 1.13 1.20 1.35 1.50 1.64 1.79
870 0.45 0.54 0.63 0.72 0.81 0.90 0.99 1.08 1.17 1.26 1.35 1.44 1.61 1.79 1.96 2.14
950 0.49 0.59 0.69 0.79 0.89 0.99 1.08 1.18 1.28 1.37 1.47 1.57 1.76 1.95 2.14 2.32
1160 0.60 0.72 0.84 0.96 1.08 1.20 1.32 1.44 1.56 1.67 1.79 1.91 2.14 2.36 2.59 2.81
1425 0.74 0.89 1.03 1.18 1.33 1.47 1.62 1.76 1.90 2.04 2.18 2.32 2.60 2.87 3.14 3.40
1750 0.91 1.09 1.27 1.45 1.62 1.80 1.97 2.15 2.32 2.49 2.66 2.82 3.15 3.47 3.77 4.07
2850 1.76 2.04 2.32 2.60 2.87 3.14 3.40 3.65 3.89 4.13 4.36 4.79 5.17 5.52 5.81
3450 2.46 2.79 3.11 3.42 3.73 4.02 4.30 4.57 4.82 5.06 5.48 5.84 6.11 6.29
100 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.14 0.15 0.16 0.17 0.19 0.21 0.23 0.25
200 0.10 0.12 0.15 0.17 0.19 0.21 0.23 0.25 0.27 0.29 0.31 0.33 0.37 0.42 0.46 0.50
300 0.16 0.19 0.22 0.25 0.28 0.31 0.34 0.37 0.41 0.44 0.47 0.50 0.56 0.62 0.69 0.75
400 0.21 0.25 0.29 0.33 0.37 0.42 0.46 0.50 0.54 0.58 0.62 0.67 0.75 0.83 0.91 1.00
500 0.26 0.31 0.36 0.42 0.47 0.52 0.57 0.62 0.68 0.73 0.78 0.83 0.93 1.04 1.14 1.24
600 0.31 0.37 0.44 0.50 0.56 0.62 0.69 0.75 0.81 0.87 0.93 1.00 1.12 1.24 1.36 1.49
700 0.36 0.44 0.51 0.58 0.65 0.73 0.80 0.87 0.94 1.02 1.09 1.16 1.30 1.45 1.59 1.73
800 0.42 0.50 0.58 0.67 0.75 0.83 0.91 1.00 1.08 1.16 1.24 1.32 1.49 1.65 1.81 1.97
900 0.47 0.56 0.65 0.75 0.84 0.93 1.03 1.12 1.21 1.30 1.40 1.49 1.67 1.85 2.03 2.21
1000 0.52 0.62 0.73 0.83 0.93 1.04 1.14 1.24 1.34 1.45 1.55 1.65 1.85 2.05 2.25 2.44
1100 0.57 0.69 0.80 0.91 1.03 1.14 1.25 1.36 1.48 1.59 1.70 1.81 2.03 2.25 2.46 2.67
1200 0.62 0.75 0.87 1.00 1.12 1.24 1.36 1.49 1.61 1.73 1.85 1.97 2.21 2.44 2.67 2.90
1300 0.63 0.81 0.94 1.08 1.21 1.34 1.48 1.61 1.74 1.87 2.00 2.13 2.38 2.63 2.88 3.12
1400 0.73 0.87 1.02 1.16 1.30 1.45 1.59 1.73 1.87 2.01 2.15 2.29 2.56 2.82 3.09 3.34
1500 0.78 0.93 1.09 1.24 1.40 1.55 1.70 1.85 2.00 2.15 2.30 2.44 2.73 3.01 3.29 3.56
1600 0.83 1.00 1.16 1.32 1.49 1.65 1.81 1.97 2.13 2.29 2.44 2.60 2.90 3.20 3.49 3.77
1700 0.88 1.06 1.23 1.41 1.58 1.75 1.92 2.09 2.26 2.42 2.59 2.75 3.07 3.38 3.68 3.97
1800 1.12 1.30 1.49 1.67 1.85 2.03 2.21 2.38 2.56 2.73 2.90 3.23 3.56 3.87 4.17
1900 1.18 1.37 1.57 1.76 1.95 2.14 2.32 2.51 2.69 2.87 3.05 3.40 3.73 4.05 4.36
2000 1.24 1.45 1.65 1.85 2.05 2.25 2.44 2.63 2.82 3.01 3.20 3.56 3.90 4.23 4.54
2200 1.36 1.59 1.81 2.03 2.25 2.46 2.67 2.88 3.09 3.29 3.49 3.87 4.23 4.57 4.89
2400 1.49 1.73 1.97 2.21 2.44 2.67 2.90 3.12 3.34 3.56 3.77 4.17 4.54 4.89 5.21
2600 1.61 1.87 2.13 2.38 2.63 2.88 3.12 3.36 3.59 3.82 4.04 4.45 4.84 5.19 5.50
2800 1.73 2.01 2.29 2.56 2.82 3.09 3.34 3.59 3.83 4.07 4.30 4.72 5.11 5.45 5.75
3000 1.85 2.15 2.44 2.73 3.01 3.29 3.56 3.82 4.07 4.31 4.54 4.98 5.36 5.69 5.97
3200 2.29 2.60 2.90 3.20 3.49 3.77 4.04 4.29 4.54 4.78 5.21 5.59 5.90 6.14
3400 2.42 2.75 3.07 3.38 3.68 3.97 4.25 4.51 4.77 5.00 5.43 5.79 6.07 6.27
3600 2.56 2.90 3.23 3.56 3.87 4.17 4.45 4.72 4.98 5.21 5.63 5.97 6.21 6.35
3800 2.69 3.05 3.40 3.73 4.05 4.36 4.65 4.92 5.17 5.41 5.81 6.11 6.31 6.39
4000 2.82 3.20 3.56 3.90 4.23 4.54 4.84 5.11 5.36 5.59 5.97 6.23 5.96.37 6.37
4200 3.34 3.71 4.07 4.40 4.72 5.02 5.29 5.53 5.75 6.10 6.32 6.39 6.30
4400 3.49 3.87 4.23 4.57 4.89 5.19 5.45 5.69 5.90 6.21 6.37 6.36 #6.17
4600 3.63 4.02 4.39 4.74 5.06 5.35 5.61 5.84 6.03 6.29 6.39 6.29 #5.98
4800 3.77 4.17 4.54 4.89 5.21 5.50 5.75 5.97 6.14 6.35 6.37 #6.17 #5.73
5000 3.90 4.31 4.69 5.04 5.36 5.64 5.88 6.09 6.23 6.38 6.31 #6.00 #5.41
5200 4.04 4.43 4.84 5.19 5.50 5.77 6.00 6.18 6.30 6.38 6.22 #5.78 #5.03
5400 4.17 4.59 4.98 5.32 5.63 5.89 6.10 6.25 6.35 6.36 6.36 #5.50 #4.57
5600 4.30 4.72 5.11 5.45 5.75 6.00 6.19 6.32 6.38 6.30 #3.90 #5.17 #4.05
5800 4.42 4.85 5.24 5.58 5.86 6.09 6.26 6.36 6.39 6.21 #5.68 #4.77 #3.44
6000 4.54 4.98 5.36 5.69 5.97 6.18 6.32 6.38 6.37 #6.08 #5.41 #4.32 #2.76
This pulley and RPM can be used only if a corresponding reduction in belt service life is allowable.
green%20color.jpg Pulley Surface speeds over 6500 fpm: special pulleys are required.