Manual

SB-7- 621 Page 15
Dimensions
(Inches)
Gear
Diameter
(Inches)
A B C
(Max)
Maximum
Allowable
Moment
(LB - IN)
2 2.76 .80 .38 146
3 2.8 8 .85 .38 385
4 3.49 1.10 .38 490
5 3.90 1.40 .38 1245
MAXIMUM ALLOWABLE MOMENT
DRIVE SHAFT ILLUSTRATION
Z Ac Z Ac Z Ac Z Ac Z Ac Z Ac
0.000 1.000 0.250 0.966 0.500 0.926 0.750 0.879 1.000 0.823 1.250 0.751
0.025 0.997 0.275 0.962 0.525 0.922 0.775 0.874 1.025 0.816 1.275 0.742
0.050 0.994 0.300 0.958 0.550 0.917 0.800 0.869 1.050 0.810 1.300 0.734
0.075 0.990 0.325 0.954 0.575 0.913 0.825 0.864 1.075 0.803 1.325 0.725
0.100 0.987 0.350 0.951 0.600 0.908 0.850 0.858 1.100 0.796 1.350 0.716
0.125 0.983 0.375 0.947 0.625 0.904 0.875 0.852 1.125 0.789 1.375 0.706
0.150 0.980 0.400 0.943 0.650 0.899 0.900 0.847 1.150 0.782 1.400 0.697
0.175 0.977 0.425 0.939 0.675 0.894 0.925 0.841 1.175 0.774 1.425 0.687
0.200 0.973 0.450 0.935 0.700 0.889 0.950 0.835 1.200 0.767
0.225 0.969 0.475 0.930 0.725 0.884 0.975 0.829 1.225 0.759
ARC OF CONTACT FACTORS
Belt Pull = 2.5 – Ac
X 125954 x Hp x S.F.
Ac D x RPM
Key: Ac = Arc of Contact Factor (Re fer to Arc of Contact Factor Chart above)
Hp = Blower Horsepower for Operating Conditions
S.F. = Actual Drive Serv i ce Factor
D = Blower Sheave Pitch Diameter in Inches
RPM = Blower Sheave Speed
Z = Large Sheave Pitch Diameter (in) – Small Sheave Pitch Diameter (in
)
Sheave Center Distance (in)
CALCULATION OF BELT PULL
Shaft Moment (LB - IN) = Belt Pull x B + C + Sheave Width
2
CALCULATION OF SHAFT MOMENT
FIGURE 2-2 – BELT DRIVE OVERHUNG LOAD CALCULATIONS