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Centering Fan Wheel — If fan and fan shaft assem-
bly are not properly centered, blades may scrape against scroll
or may create an objectionable whistling noise. It may be
necessary to adjust individual fan wheels or move entire fan
shaft. See the following two sections.
Fan Shaft Position Adjustment — Loosen set-
screw or locking collar of each fan shaft bearing. Slide shaft
into correct position and replace locking collar (Fig. 18). To
replace locking collar, push collar up against inner face of
bearing. 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.
Individual Fan Wheel Adjustment — Loosen the
2 locking bolts holding fan wheel hub to shaft. See Fig. 17.
Position fan wheel in center of the fan housing and tighten
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 permit both vertical and horizontal
adjustment. Adjust belt(s) for correct deflection by loosen-
ing motor plate mounting bolts, moving motor/plate assem-
bly forward or back, and retightening 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. 19.
NOTE: The 028 and 034 size units with 60 Hz motors are
shipped with an extra set of matching belts. Use the pre-
installed belts or extra belts depending on the adjustable
pulley setting.
If complete belt replacement is required during serv-
icing, loosen the motor plate mounting bolts (Fig. 19), move
motor/plate assembly towards fan pulley, and pull belt(s) off
pulleys. Reverse the procedure with new bolts and readjust
deflection.
Fan Rotation — Correct fan rotation with respect to
fan outlet is shown in Fig. 20.
To reverse the direction of rotation of a 3-phase fan mo-
tor, reverse any 2 of the power leads. Refer to the connection
diagram on the inside of motor terminal box cover for proper
reversing procedure of single-phase motor.
Fig. 18 — Fan Shaft Bearing
Fig. 19 — Fan Motor Mounting
24