16
Arc of Contact Correction Factors G and R
Table 3-3
D-d
C*
Small Sheave
Arc of
Contact
Factor
G
Factor
R
D-d
C*
Small Sheave
Arc of
Contact
Factor
G
Factor
R
.00
180°
1.00
1.000
.80
133°
.87
.917
.10
174°
.99
.999
.90
127°
.85
.893
.20
169°
.97
.995
1.00
120°
.82
.866
.30
163°
.96
.989
1.10
113°
.80
.835
.40
157°
.94
.980
1.20
106°
.77
.800
.50
151°
.93
.968
1.30
99°
.73
.760
.60
145°
.91
.964
1.40
91°
.70
.714
.70
139°
.89
.937
1.50
83°
.65
.661
*D = diameter of large sheave; d = diameter of small sheave; C = center distance.
Bearing Load Calculations
To find actual bearing loads it is necessary to know
machine component weights and values of all other
forces contributing to the load. Sometimes it
becomes desirable to know the bearing load
imposed by the V-belt drive alone. This can be
done if you know bearing spacing with respect to
the sheave center and shaft load (see Figure 3-3)
and apply it to the following formulae:
Load at B, Lbs. = Shaft Load (a+b)
A
Load at A, Lbs. = Shaft Load (b)
a
Where: a and b = spacing, inches
Allowable Sheave Rim Speed*
Table 3-4
Sheave Material
Rim speed in feet per
minute
Cast iron
Ductile Iron
Steel
6,500
8,000
10,000
*These rim speed values are maximum for normal
considerations. In some cases, these values may
be exceeded. Consult factory and include complete
details of proposed application.
Overhung Sheave
Figure 3-3
