Twin City Axial Roof Ventilators and Tubeaxial Fans - IM-4000 - Manual (Page 3)

Twin City IM-4000 3
Maintenance
1. Before performing any maintenance on the fan, be
sure power is turned off and locked in the OFF
position at the service entrance.
2. Ventilators should be carefully checked at least once
a year. For critical or rugged applications, a routine
check every two or three months is suggested.
3. All motors supplied with Twin City Fan & Blower
ventilators carry a one-year limited warranty from
date of shipment. For repairs within the warranty
period, the motor must be taken to the motor
manufacturer’s authorized service dealer. Contact
your representative for additional warranty details.
4. A periodic motor check should consist of spinning
the motor shaft with the power off to be sure the
motor turns freely and the bearings run smoothly.
The belt on belt driven units should be removed
from the motor sheave.
5. When removing or installing a belt, do not force
the belt over the sheave. Loosen the motor mount
so that the belt can be easily slipped over the
sheave.
6. The belt on belt driven units should be removed and
carefully checked for glazing, cracks, ply separation
or irregular wear. A small irregularity in the contact
surface of the belt will result in noisy operation. If
any of these defects are apparent, the belt should
be replaced. Check the sheaves also for chipping,
dents or rough surfaces which could damage the
belt.
7. The correct belt tension is important. Too tight of
a belt will result in excess bearing pressure on the
motor bearings and shaft pillow blocks and may
also overload the motor. Too loose of a belt will
result in slippage which will quickly “burn” out belts.
A belt should feel “live” when thumped, approxi-
mately 1 ⁄
4
" belt deflection (3 to 5 lb.) when subject
to finger pressure at midpoint between sheaves.
8. The belt alignment should also be checked to be
sure the belt is running perpendicularly to the rotat-
ing shafts. Fan and motor shafts must be paral-
lel. Improper alignment will result in excessive belt
wear.
9. Check sheave setscrews to ensure tightness. Proper
keys must be in keyways.
10. Do not readjust blade pitch or fan RPM. If sheaves
are replaced, use only sheaves of identical size and
type.
11. If unit is to be left idle for an extended period, it is
recommended that belts be removed and stored in
a cool, dry place to avoid premature belt failure.
12. The standard pillow block bearings on belt driven
ventilators are factory lubricated and are provided with
external grease fittings. Annual relubrication is recom-
mended, or more frequently if needed (see Table 2).
Do not over-grease. Use only 2 or 3 shots of
a recommended lubricant with a hand gun in most
cases (see Table 3). Maximum hand gun rating 40
P.S.I. Rotate bearings during lubrication where good
safety practice permits.
CAUTION: Greases of different soap bases
(lithium, sodium, etc.) may not be compatible when
mixed. Prevent such intermixing by completely purg-
ing the bearing of old greases.
The most frequent causes of bearing failure are
not greasing often enough, using an excessive
quantity of grease, or using incompatible greases.
Excessive vibration, especially if the bearing is not
rotating, will also cause bearings to fail. Bearings
must also be protected from water and moisture to
avoid internal corrosion.
13. During the first few months of operation it is rec-
ommended that the bearing setscrews be checked
periodically to ensure that they are tight.
14. The rotating wheel or propeller requires particular
attention since materials in the air being handled
can build up on the blades to cause destructive
vibration or weaken the structure of the propel-
ler by corroding and/or eroding the blade metal.
Regular inspection and corrective action at intervals
determined by the severity of each application are
essential to good service life and safety.
Table 2. Suggested Fan Bearing Greasing Intervals
INTERVAL
TYPE OF SERVICE
(MONTHS)
12 to 18 Infrequent operation or light duty in clean atmosphere.
6 to 12 8 to 16 hrs./day in clean, relatively dry atmosphere.
3 to 6 12 to 24 hrs./day, heavy duty, or if moisture is present.
1 to 3
Heavy duty in dirty, dusty locations; high ambient
temperatures; moisture laden atmosphere; vibration.
Table 3. Grease Manufacturers
WARNING: Check units for rotation. For three-phase,
rotation can be changed by interchanging any two of
the three line leads. If unit is checked on temporary
wiring, it should be rechecked when permanently
installed. Motor burn-out or tripped overload protec-
tion devices are usually the result of wrong rotation.
4. Electrical Input Check: Perform check of fan ampere
draw and verify that motor nameplate amps are not
exceeded. Take into account the service factor range
if motor is nameplated above a 1.0 service factor.
5. Fan RPM should be checked and verified with a
tachometer.
NOTE: The fan was balanced at the factory to be
within stringent vibration levels before shipment.
However, there are several things that may cause
vibration, such as rough handling in shipment and
installation, weak foundations and alignments.
MANUFACTURER GREASE (NLGI #2)
Shell Gadus S2 V100 2
Exxon/Mobil Ronex MP