SB
-7-
621 Page
14
Exceeding overhung load limitations leads to unwarrantable premature bearing failure an
d shaft
breakage.
The location of the sheave on the blower shaft greatly affects the stress in the shaft. The optimum blower sheave
positioning is as close as possible to the blower drive cover, not to exceed dimension “C” in Drive Shaft
Illustration,
FIGURE
2-2
, page
15
The calculated shaft moment must not exceed the maximum allowable moment listed in Maximum Allowable
Moment Chart,
FIGURE
2-2
page
15
. If the calculated shaft moment exceed the maximum allowable moment:
Increase Sheave Diameters to Reduce Belt Pull
Use Jackshaft Drive
Use Direct Coupled or Gearbox Drive
To calculate shaft moment for a given
V-
Belt Drive Arrangement:
1.
Use the formula for Calcul
a
tion of Belt Pull,
FIGURE
2-2
, page
15
, to calculate belt pull. Refer to Arc of
Contact Factor Chart, Figure 2
-2
, page
1
5.
2.
Inse
rt the calculated belt pull into the formula for Calculation of Shaft Moment,
FIGURE
2-2,
page
15
to
arrive at the calculated shaft moment.
PIPING
Inlet and discharge
connections on all blowers are large enough to handle maximum volume with minimum
friction loss. Reducing the pipe diameter on either inlet or discharge will only create additional line loss and
increase the overall pressure differential. Excessive weight of piping and fittings will cause internal misalignment
and premature wear. Never allow the blower to carry the weight of the pipe. If possible, a spool or sleeve
-
type
expansion joint should be installed between the unit and the piping. Where a flexib
le connection is not practical,
the weight of the rigid connection must be separately supported.
All system piping must be cleaned internally before connecting to the blower.
Sutorbilt blowers are shipped dry from the factory. Do not attempt to ope
rate the blower before
following proper lubrication instructions. Permanent damage to the gears, bearings and seals will
occur.
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