SRUB-IOM001-EN 23
Belt Maintenance
Clean fan belts and pullies with a dry cloth. Oil and grease
must be kept off belts. The use of a belt dressing is not
recommended. When replacing belts, use a matched set. Do
not force belts onto pullies, but adjust motor position to allow
mounting and then re-tighten.
Figure 7 : Belt Tension Measurement
Maintenance
To measure belt tension, use a belt tensioner as shown in
Figure 7. Determine actual deflection by depressing one belt
with the belt tensioner and then adjust the belt tension to the
correct pounds force and tighten all setscrews to the proper
torques.
Fan Drive Maintenance
Perform the following procedures at the intervals
recommended
1. Rotate the fan wheel to be sure that it turn freely in the
proper direction of rotation and is not rubbing on the fan
housing, inlet. If necessary, re-center the fan wheel.
2. Check the position of both shafts. Fan and motor shafts
should operate parallel to each for maximum belt and
bearing life. Shim as necessary under the motor or fan
bearing to obtain proper alignment.
3. Check the fan motor sheave alignment with a straightedge
or a tightly pulled string. For sheaves of different widths,
place a string in the center groove of each sheave and pull
it tight for a center line. See Figure 8.
4. Once the sheaves are properly aligned, tighter sheave set
screws to proper torque.
5. Check belt tension. Refer to “Measuring Belt Tension”.
6. If required, adjust belt to the minimum recommended
tension. Refer to “Adjusting Belt Tension”.
7. Re-tighten bearing setscrews to the proper torques after
aligning the sheaves.
8. Check the fan bearing locking collars for tightness on the
shaft. To tighten the locking collar, loosen the setscrew and
slide the collar into its proper position over the extended
end of the inner case.
9. During air balancing, be sure to check the shaft parallel,
sheave alignment and belt tension.
Span
Force
Deflection
WARNING : Disconnect electrical power
source to prevent injury or death from electrical shock.
Figure 8 : Fan Shaft and Motor Sheave Alignment
Fixed Sheave
Straight edge should
touch sheave at top
and bottom.
Straight edge
Straight edge should
touch sheave at top
and bottom.
Fixed Sheave
Straight edge
Fixed Sheave
Lines must be parallel.
For uneven width sheaves,
use a taut string down the
center of both sheaves.
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