SCXF-SVX01T-EN
79
Figure 41. Fan shaft and motor sheave alignment
Fan Bearings
The opposite drive end bearing is a special bearing with
close tolerance fit of balls and races. Replace this bearing
with the same part number as the original bearing.
NOTICE
Bearing Failure!
Do not mix greases with different bases within the
bearing as it could result in premature bearing failure.
Table 38. AO smith bearing lubrication schedule
Speed
Service
Over 1800
rpm
Frame
All
Standard
Service
6 months
Severe
Service
3 months
Extreme
3 months
1800 rpm
140-180
3 yrs 1 yr
6 mths
210-280
2 1/2 yrs
10 1/2 mths 5 1/2 mths
320-360
2 yrs
9 mths 4 1/2 mths
400-440
1 1/2 yrs
8 mths 4 mths
Note: Service standard - 8 hrs/day, normal to light loading, 100°F ambient
temp. max. Severe service - 24 hrs/day, shock loading, vibration,
dirt or dust, 100°F to 150°F ambient temp. Extreme service - heavy
shock or vibration, dirt or dust, 100°F to 150°F ambient temp.
Table 39. Compatible with NLGI grade 2 lithium fan
bearing greases
Type
Shell Alvania EP2
Mobile SHC 220
FINA LICAL
Table 40. Compatible with NLGI grade 2 lithium fan
bearing greases
Recommended Grease Recommended Operating
Range
FINA LICAL
Shell Alvania EP2
Mobile SHC 220
20°F to 205°F
Fan Belt Tension
Note: Check fan belt tension at least twice during the first
days of new belt operation since there is a rapid
decrease in tension until belts are run-in.
Proper belt tension is necessary to endure maximum
bearing and drive component life and is based on fan brake
horsepower requirements. If frayed or worn, replace belts
in matched sets.
Measuring Belt Tension
Measure fan belt tension with a Browning, Gates, or
equivalent belt tension gauge. Determine deflection by
dividing the belt span distance (in inches) by 64. See
Figure 42, p. 80. Use the following procedure to measure
belt tension:
1. Measure belt span between centers of sheaves and set
the large “O” ring of the tensioning gauge at 1/64 inch
for each inch of belt span.
2. Set the load “O” ring at zero.
3. Place the large end of the gauge at the center of the
belt span. Press down until the large “O” ring is even
with the top of the belt line or the next belt as in Figure
42, p. 80. Place a straight edge across the sheaves as
a reference point. See Figure 41, p. 79.
4. Remove the gauge. Note that the load “O” ring now
indicates a number on the plunger scale. This number
represents pounds of force required to deflect the belt.
5. Check the reading from step 4 against the values given
in . If necessary, readjust belt tension.
Table 41. Fan hub and sheave torques
Unit size Fan Diameter Set Screw
Size
Torque (ft-
lbs)
SCWF 20
18" 5/16" 12SCWF 22
SCWF 25
SCWF 29
18" 5/16" 12
SCWF 32
SCWF 35
20" 5/16" 14
SCWF 38
Maintenance
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