MK Plastics AXTC Centrifugal Inline Fan IO&M - Manual (Page 5)

M.K. Plastics Corp. Montréal, Québec www.mkplastics.com Page. 5
Fan Bearing Lubrication
Proper lubrication of the fan drive bearings helps assure
maximum bearing life. All AXTC bearings are lubricated
through a grease fitting on the outer housing and should
be lubricated by the schedule, Table 2. However, every
installation is different and the frequency of relubrication
should be adjusted accordingly.
On high moisture applications, the lubrication frequency
may need to be doubled or tripled to adequately protect the
bearings. Double the relubrication frequency on fans with
vertical shafts.
Observation of the conditions of the grease expelled from the
bearings at the time of relubrication is the best guide as to
whether regreasing intervals and amount of grease added
should be altered.
Greases are made with different bases. There are synthetic
base greases, lithium base, sodium base, etc. Avoid mixing
greases with different bases. They could be incompatible
and result in rapid deterioration or breakdown of the grease.
All bearings are filled with a lithium-based grease before
leaving the factory. When the fans are started, the bearings
may discharge excess grease through the seals for a short
period of time. Do not replace the initial discharge because
leakage will cease when the excess grease has worked out.
Sometimes the bearings have a tendency to run hotter during
this period. There is no reason for alarm unless it lasts over
48 hours or gets very hot (over 200°F). When relubricating,
use a sufficient amount of grease to purge the seals. Rotate
bearings by hand during relubrication.
Fan Bearing Replacement
Replacement of bearings requires disassembly of internal
components. For this procedure access must be available
to both the inlet/outlet ends and the lower fan casing half,
although it possible on smaller fans for bearing replacement
without access to the fan inlet. The following procedure
assumes belts have already been loosened and removed.
(Belts are removed by adjusting the motor pivot plate).
Relubrication Schedule [Months]
Speed [rpm] 500 1000 1500 2000 2500 3000
Size
1825 6 6 5 3 3 3
2225 6 6 5 3 3 -
2450 6 6 5 3 - -
2700 6 6 5 3 - -
3000 6 5 4 - - -
3300 6 5 4 - - -
3650 6 5 - - - -
4025 5 4 - - - -
4450 5 4 - - - -
4900 5 4 - - - -
5425 5 4 - - - -
6000 4 3 - - - -
Table 2. - Relubrication Schedule [Months]
AXCT fans have split-pillow block type bearings on horizontal
applications and the addition of a flange-type bearing on
vertical applications. Replacement is similar for both. Refer
to the fan parts list on Page 8.
1. Unbolt and remove the lower casing section, belt and
shaft guards.
2. Remove the inlet cone by removing the bolts around the
perimeter.
3. Remove the wheel hub cover, loosen the wheel bushing
and slide the wheel off the shaft. Note, on smaller fans
it may be possible to leave the wheel on the shaft and
remove the wheel/shaft/bearing assembly as one piece
out of the fan housing.
4. Note the location of the fan sheave on the end of the
shaft and remove the sheave.
5. Note the distance from the bearing to the end of the
shaft.
6. Unbolt both sets of bearings from the support plates and
remove the shaft/bearing assembly out the fan casing.
7. Reinstall components in reverse order of removal and
reference the Overlap, Radial Gap and Alignment
sections on Page 3. and 4.
8. Test run the fan and retighten all hardware, trim balance
if necessary.
Changing Shaft Speed
All belt driven fans with motors up to and including 5 HP
are equipped with variable pitch pulleys. To change the fan
speed, perform the following:
1. Loosen setscrew on driver (motor) pulley and remove
key, if equipped.
2. If the pulley has multiple grooves, all must be adjusted
to the same width.
3. After adjustment, inspect for proper belt tension.
4. To reduce speed, open the pulley in order that the belt
rides deeper in the groove (smaller pitch diameter).
5. To increase speed, close the pulley so that the belt rides
higher in the groove (larger pitch diameters). Make sure
the maximum fan RPM and motor HP is not reached.