McQuay IM 987 109
Maintenance
BOA Concentric Inserts
1 Be sure that BOA Concentric collar is fitted square and
snug against the shoulder on the inner ring.
2 Torque BOA Concentric collar cap screw to torque
recommended in Table 21.
Note: AF = DWDI AF, SWSI = AF Plenum Fan
Monitor Installed Bearing
After bearing has been run for several minutes, and again after
several hours, check bearing for excessive noise or vibration.
Shutdown machine and check housing temperature: typical
applications operate at 100°F - 105°F (38°C - 66°C). Tighten
all locking devices after 500 hours or 3 months, whichever
comes first.
Propeller Exhaust
For information, see "Propeller Exhaust Fan Option"‚ page 91.
Vibration Levels
Each unit as shipped is trim balanced to operate smoothly. To
provide satisfactory operation after shipping and installation,
use accepted industry guidelines for field balancing fans. See
Table 22.
Note: Excessive vibration from any cause contributes to
premature fan and motor bearing failure. Monitor overall
vibration levels every six months of operation. An
increase in levels is an indication of potential trouble.
Vibration Causes
1 Wheel imbalance.
a Dirt or debris on wheel blades.
b Loose setscrews in wheel hub or bearing-to-shaft.
c Wheel distorted from overspeed.
2 Bent shaft.
3 Faulty drive.
a Variable pitch sheaves—Axial and radial runout of
flanges; uneven groove spacing; out of balance. Also
similar faults in driven sheave.
b Bad V-belts; lumpy, or mismatched; belt tension too
tight or too loose.
4 Bad bearings, loose bearing hold-down bolts.
5 Motor imbalance.
6 Fan section not supported evenly on foundation.
Periodic Service and Maintenance
1 Check all moving parts for wear every six months.
2 Check bearing collar, sheave, wheel hub setscrews,
sheave capscrews, and bearing hold-down bolts for
tightness every six months.
Setscrews
Setscrews are used to lock bearings, sheaves, locking collars,
and fan wheels to their shafts. They must be checked
periodically to see that they have not loosened. If this is not
done, severe equipment damage could occur.
Refer to Table 23 and check the tightness of all setscrews with
a torque wrench. Note that if the return fan bearings setscrews
must be retightened, a special procedure is required to equally
load both bearings (see “Return Fan Bearing Setscrews”
below).
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
provide 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 the fan shaft
support in Figure 119, page 110). Important: 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.
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 bearing setscrews to the torque
specification given in Table 23. Remove the fan shaft
support and re-tension the belts.
Table 21: Recommended Torque Values for Concentric
Locking Bearing/Shaft Size
Fan Size (in) Bore Size (in)
Torx Screw
Size
In lbs.
27 (AF)/40 & 49
(SWSI)
2-3/16 T-30 180
30 & 33 (AF)/44
(SWSI)
2-7/16 T-45 400
36 (AF) 2-11/16 T-45 400
40 (AF) 2-15/16 T-45 400
Table 22: Vibration Levels
Fan speed (RPM) Vibration
800 or less 5 mils maximum displacement
801 or greater 0.20 in/sec maximum velocity
Table 23: Setscrew Minimum Torque Specifications
Setscrew diameter (in.) Minimum torque (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
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