Twin City Upblast Propeller Roof Fans - IM-4870 - Manual (Page 6)

6 Twin City IM-4870
15. Filter Maintenance (Filtered Supply Fans)
Inspect the 2" Aluminum Mesh Filters on a regular
basis. Clogged filters can adversely affect air per-
formance.
On all fan sizes the filters can be removed with the
hood in place by removing the filter retainers from the
hood end panels and sliding them out of the filter rails.
On sizes 21-30 it is recommended to remove the 1½"
bolts connecting the hood side rails to the hood mount
bars on the fan housing on one side and loosen the
ones on the opposite side and tilt the hood back to
gain access. Wash filters with a mild detergent in warm
water.
Fan bearings on belt driven fans should not need to be
replaced for many years if the previous recommenda-
tions are strictly adhered to. However, use the following
procedure when bearing replacement is necessary.
1. Gain access to the fan bearings. Remove the bear-
ing cover, if any.
2. Loosen the belts by shifting the motor.
3. Remove the propeller and disconnect the remote
lubrication tubes (if applicable).
4. Measure the location of the bearing to the propeller
end of the shaft and the bearing spacing.
5. Remove the shaft and bearing assembly. Note the
position of the bearings’ shims (if applicable).
6. Loosen all bearing/shaft setscrews or other locking
devices.
7. Remove bearings (may need to be pressed off the
shaft).
8. Polish the shaft with fine emery paper (240 grit or
finer) and file the setscrew dimples left on the shaft
flat.
9. Install new bearings on the shaft, making sure that
the collars are together (i.e. facing each other on the
Bearing Replacement
Motors
shaft). Lightly seat one setscrew or eccentric locking
collar on each bearing to hold in the approximate
marked position.
10. Mount the shaft/bearing assembly in the fan with
bolts. Do not tighten yet. Just snug up. Loosen the
setscrew.
11. Center the shaft in the housing (both ends) as
closely as possible. (The fan propeller may need
to be temporarily installed to get its clearances
equal.)
12. Lubricate bearings. See Tables 1 and 2, Page 5.
13. Tighten setscrews in steps (alternating half turns).
Note torquing requirements with bearing instruc-
tions.
14. Tighten the bearing mounting bolts.
15. Reinstall the lube tubes (if applicable).
16. Install propeller and belts and adjust the motor to
get proper belt tension. Also, make sure that the
sheaves are properly aligned.
17. If a new shaft is supplied, ignore items 6 thru 8.
Twin City Fan & Blower recommends periodic checks
of voltage, frequency and current of a motor while in
operation. Such checks assure the correctness of fre-
quency and voltage applied to the motor, and yield an
indication of the fan load. Comparison of this data with
previous data will give an indication of the fan perfor-
mance. Any serious deviations could indicate a potential
motor failure.
All motors have prelubricated sealed bearings and are
lubricated for the life of the motor.
1. All motors carry a limited warranty from the motor
manufacturer. 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.
2. 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 pulley.
Repair or replacement of motors is normally performed
by a repair station authorized by the manufacturer.
Contact your representative or the factory for locations
nearest you. DO NOT ship motor to the factory without
specific authorization forms.