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Table 14. Recommended greases
PRODUCT
TEMP.
MANUFACTURER
NAME
RANGE (
°
F)
Texaco Lubricants Co.
Premium RB
–30 to 300
Keystone Ind. Lubricants
84EP-2
–40 to 200
Mobil Oil Corporation
Mobilith AW2
–40 to 325
Chevron U.S.A. Inc.
SRI-2
–20 to 325
Exxon Company, U.S.A.
Ronex MP
–40 to 300
Shell Oil Company
Alvania No. 2
–20 to 240
Table 15. Recommended fan shaft bearing
relubrication interval
OPERATING
BEARING AMBIENT TEMPERATURE
DUTY
TO 130
°
F
TO 150
°
F
OVER 150
°
F
Continuous
6 months
4 months
2 months
12 Hrs./Day
12 months
12 months
6 months
3. Run the motor for five minutes before replacing the plugs.
Note: Specific greasing instructions may be found on a
tag attached to the motor. If special lubrication instructions
are on the motor, they will supersede all other instructions.
Fan shaft bearings
Fan shaft bearings should be relubricated periodically. Re-
lubricate according to the schedule shown in Table 15. If the
bearings are exposed to wet conditions, wide temperature
variations, or other severe atmospheric conditions, relu-
bricate more frequently. Use one of the greases shown in
Table 14.
While the bearing is at normal operating temperatures,
rotate the fan by hand and add only enough grease to purge
the seals. The seals will bleed slightly when this has occurred.
Do not overlubricate.
Setscrews lock bearings, sheaves, locking collars, and fan
wheels to their shafts. It is very important that all setscrews
be checked periodically to assure that they have not loos-
ened. If this is not done, severe equipment damage could
occur.
Using Table 16, check the tightness of all setscrews with
a torque wrench. Note that if the return fan bearings set-
screws must be retightened, a special procedure is required
to equally load both bearings (see below).
Table 16. Setscrew minimum torque specifications
SETSCREW DIAMETER
MINIMUM TORQUE
(IN.)
(FT-LB)
1/4
5.5
5/16
10.5
3/8
19.0
7/16
29.0
1/2
42.0
5/8
92.0
Return fan bearing setscrews
Because the return fan is mounted on a vertical shaft, the
following procedure must be used to retighten any return fan
bearing setscrews that have loosened. This procedure will
assure that both bearings are equally loaded. If one bearing is
carrying the entire weight of the fan, it could fail prematurely.
1. Loosen the fan belts.
2. Support the weight of the fan and the fan shaft with
timbers or some other suitable means (see Figure 36).
Important: In order to maintain proper drive alignment
and fan-to-tunnel clearance, the fan and shaft must not drop
at all when the setscrews are loosened in Step 4 below.
Setscrews
3. Verify that the upper shaft collar is securely fastened to
the shaft. Check the setscrew torque.
4. Loosen the upper and lower bearing setscrews. The entire
weight of the fan and shaft is now supported by the fan
shaft support.
5. Retighten all bearings to the torque specification given in
Table 16 above.
6. Remove the fan shaft support and retension the belts.
Figure 36. Return fan assembly
Fan Shaft
Upper Bearing
Fan Wheel
Lower Bearing
Fan Shaft
Support
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