29
Fig. 22 — Fan Shaft, Bearings, and Fan Wheel
(Typical)
Centering Fan Wheel
If fan and fan shaft assembly are not properly centered, blades
may scrape against the blower side scroll plate or may create an
objectionable whistling noise. It may be necessary to adjust
individual fan wheels or move entire fan shaft. See the following
2 sections.
Fan Shaft Position Adjustment
Loosen setscrew or locking collar of each fan shaft bearing. Slide
shaft into correct position and replace locking collar. (See Fig. 23).
To replace locking collar, push collar up against inner face of bear
-
ing. Turn collar in direction of fan rotation until tight, and tighten
setscrew. Tightening locking collar in direction of fan rotation
results in further tightening of collar should setscrew work itself
loose.
Fig. 23 — Fan Shaft Bearing
Individual Fan Wheel Adjustment
Loosen the 2 locking bolts holding the fan wheel hub to shaft. (See
Fig. 22.) Position fan wheel in center of the fan housing and tight
-
en locking bolts. Clearance between wheel and housing should be
the same on both sides.
Fan Belts
Motor mounting plate and motor support angles are slotted to per
-
mit both vertical and horizontal adjustment. Adjust belt(s) for
correct deflection by loosening motor plate mounting bolts, mov
-
ing motor/plate assembly forward or back, and re-tightening bolts.
Press down on belt with one finger midway between fan and
motor pulleys to check deflection. For units with motor sizes up to
and including 3.7 Hp (2.76 kW), correct deflection is 3/16 in.
(4.8 mm). For larger motor sizes, correct deflection is 1/8 in.
(3.2 mm). (See Fig. 24.)
If complete belt replacement is required during servicing, loosen
the motor plate mounting bolts (Fig. 24), move motor/plate assem
-
bly towards fan pulley, and pull belt(s) off pulleys. Reverse the
procedure with new bolts and readjust deflection.
Fig. 24 — Fan Motor Mounting
