2
Twin City Engineering Supplement ES-895
Supports for suspended fans must be cross-braced to
prevent side-sway. Structural resonance should be at
least 20% from fan operating speed. Vibration isolators
may help block the transmission of vibration into a
structure.
Any ducting should have independent support; do not
use the fan to support ducting. Flexible connections are
required whenever the fan is supported on vibration
isolators.
Fan Installation, Factory Assembled Units
Follow proper handling instructions as given earlier.
1. Move the fan to the final mounting position.
2. Remove skid, crates and packing materials carefully.
3. Attach vibration isolators (if used) to appropriate
mounting clips on fan. Locate fan in position using
lifting instructions above.
4. Carefully level unit using shims (on rigid mounted
fans) at mounting hole locations. Fans mounted with
vibration isolators may be leveled by adjusting the
hardware.
5. Continue with Operations Checklist.
Motor Maintenance
The three basic rules of motor maintenance are:
1. Keep the motor clean.
2. Keep the motor dry.
3. Keep the motor properly lubricated.
Blow dust off periodically (with low pressure air) to
prevent motor from overheating.
Some smaller motors are lubricated for life. Lubrication
requirements are normally attached to the motor. Use
the motor manufacturer’s recommendations for
relubrication. If this information is not available, the
following schedule may be used. Motors less than 10
HP running about eight hours a day in a clean
environment should be lubricated once every five years;
motors 15 to 40 HP, every three years. For motors in
dusty or dirty environments or running 24 hours a day:
divide the service interval by 4. Do not over lubricate.
Drive Maintenance and Installation
V-belt drives need periodic inspection, retensioning, and
occasional belt replacement. When inspecting drives,
look for dirt buildup, burrs or obstructions that can
cause premature belt or drive replacement. If burrs are
found, use fine emery cloth or a stone to remove them.
Be careful that dust does not enter the bearings.
Check sheaves for wear. Excessive slippage of belts
on sheaves can cause wear and vibration. Replace worn
sheaves with new ones. Carefully align sheaves to avoid
premature sheave failure.
Inspect the belts for wear. If fraying or other wear is
observed to be mostly on one side of the belts, the
drives may be misaligned. Reinstall the drives according
to the following instructions:
1. Slip (do not pound) proper sheave onto corresponding
shaft.
2. Align sheaves with straightedge extended along
sheaves, just making contact in two places on
outside perimeters of both sheaves.
3. Tighten sheave bolts (or setscrews if appropriate).
Table 1 can be used to determine the amount of
torque required.
4. Install a matched set of belts. Adjust the motor
position to obtain slack, install, and tighten belts.
Using a pry bar will damage belts.
5. Tighten belts to proper belt tension. Ideal tension is
just enough so that the belts do not slip under peak
load. When using drive tensioning data supplied by
V-belt drive manufacturers, new belts can be tensioned
to a value 50% greater than for normal operation. This
will reduce retensioning requirements after break-in.
Recheck sheave alignment after tensioning.
6. After initial installation of belts, recheck belt tension
again after a few days. (New belts require a break-in
period of operation.)
7. When replacing belts, replace the entire set. After initial
replacement and tensioning, recheck belt tension after
a few days. (New belts require a break-in period of
operation.) Never use belt dressing on any belts.
8. Fans that have motors and drives mounted at the
factory are trim balanced prior to shipment. This is
not possible on units that are shipped without motors
and drives. The addition of drive components in the
field can create unbalance forces. Twin City Fan &
Blower recommends final balancing of the unit after
the drive components are installed. Failure to do so
may void the warranty.
Table 1. Tightening Torque (Ft.-Lbs.)
Tolerance: +5%
For wheel setscrews use Grade 2 values. The above torque values are for nonlubricated fasteners.
SIZE
FASTENER
TAPER BUSHINGS
GRADE 2
GRADE 5
GRADE 8
BROWNING SPLIT
QD
FOR DRIVE
IN IRON
IN ALUM. HUB
#10
—
—
—
—
—
5
1
⁄
4
-20
5.5
8
12
7.9
7.5
9
5
⁄
16
-18
11
17
25
16
13
15
3
⁄
8
-16
22
30
45
29
24
30
7
⁄
16
-14
30
50
70
—
—
—
1
⁄
2
-13
55
75
110
70
—
60
9
⁄
16
-12
—
—
—
—
—
75
5
⁄
8
-11
100
150
220
—
—
135
3
⁄
4
-10
170
270
380
—
—
—
7
⁄
8
-9
165
430
600
—
—
—
1-8
250
645
900
—
—
—
1
1
⁄
4
-7
500
1120
1500
—
—
—
Placing fan sheave on motor can overspeed
wheel and cause structural failure.
CAUTION
