Maintenance
39
6. Check pulley alignment.
•
•
•
Place a straight edge across pulleys faces to correct
alignment.
Check parallel position of shafts and correct alignment
or grooves.
Note: Store belts in a cool, dry place out of direct
sunlight.
Types of sheave and shaft misalignment
Horizontal Angular
Vertical Angular
Parallel
Align with straightedge along
sheave faces
Figure 18
Sheave Alignment
Figure 19
Belt Tension
Measurement
Note: Fan belt tension should be checked at least twice during
the first day of operation, since there is a rapid decrease in
tension until belts are run in. Proper belt tensioning is required
to ensure maximum bearing and drive component life and is
based on fan brake horsepower requirement.
Check the belt tension as follows:
Measure the span length mm of the drive. With a belt
tensioner at the center of the span, apply a force K
(perpendicular to the span) large enough to deflect the belt
15mm per 1 meter of span. Refer to figure 19.
The deflection force for the belt should be within the minimum
and maximum force shown in the Table 3. When the tension
drops to the minimum value, re-adjust to the maximum value.
To measure belt tension, use a belt tensioner as shown in
figure 20. Determine the actual deflection by depressing one
belt with the belt tensioner and measuring the deflection
relative to the other belts or to belt line. Adjust the belt tension
to the correct force (Newton) and tighten all setscrews to the
proper torques.
Fan Belt Tension
Belt Tension Measurement
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