Aerovent IM-121 - Manual (Page 9)

Aerovent IM-121 9
Three-Pulley (Idler Sheave) Assembly
Single bolt belt adjustment (Figure 9) can be made by
loosening the idler sheave bolt (with 3 /
4
" wrenches) and
moving it to the point where proper tension is achieved,
per Page 8, Figure 5. Alignment is necessary prior to
belt adjustment. See Figure 6.
This configuration is standard on ACX sizes 070-160
and ATB (family) sizes 110-180. All other adjustments
are made by moving the motor.
IDLER SHEAVE FAN SHEAVE
MOTOR SHEAVE MOTOR
Figure 9. Three-Pulley (Idler Sheave) Assembly
Maintenance
Installation and maintenance are to be performed only
by qualified personnel who are familiar with local codes
and regulations and experienced with this type of equip-
ment.
CAUTION: Sharp edges and screws are a potential injury
hazard. Avoid them.
WARNING
Hazardous moving parts. Unit may contain pro-
tected fan motor which may start automatically
and cause injury. Allow time for reset. Disconnect
power before servicing.
Preventive maintenance is the best way to avoid unnec-
essary expense and inconvenience. Start-up and routine
maintenance should cover the following items:
a. Tighten all setscrews, bolts and wire connections.
b. Check belt tension and sheaves for wear.
c. Lubricate fan bearings (see Tables 5 and 6).
d. Cleaning of unit, wheel and damper (if present).
All motors containing ball bearings are permanently
lubricated from the factory. No additional maintenance
is required.
1. Before performing any maintenance on the fan, be
sure power is turned off and locked in the OFF
position at the service entrance.
2. Ventilators should be carefully checked at least once
a year. For critical or rugged applications, a routine
check every two or three months is suggested.
3. All motors supplied with Aerovent ventilators carry
a one-year limited warranty from date of shipment.
For repairs within the warranty period, the motor
must be taken to the motor manufacturer’s autho-
rized service dealer. Contact your representative for
additional warranty details.
4. A periodic motor check should consist of spinning
the motor shaft with the power off to be sure the
motor turns freely and the bearings run smoothly.
The belt on belt driven units should be removed
from the motor sheave.
5. When removing or installing a belt, do not force
the belt over the sheave. Loosen the motor mount
so that the belt can be easily slipped over the
sheave.
6. The belt on belt driven units should be removed and
carefully checked for glazing, cracks, ply separation
or irregular wear. A small irregularity in the contact
surface of the belt will result in noisy operation. If
any of these defects are apparent, the belt should
be replaced. Check the sheaves also for chipping,
dents or rough surfaces which could damage the
belt.
7. The correct belt tension is important. Too tight of
a belt will result in excess bearing pressure on the
motor bearings and shaft pillow blocks and may
also overload the motor. Too loose of a belt will
result in slippage which will quickly “burn” out belts.
A belt should feel “live” when thumped, approxi-
mately 1 ⁄
4
" belt deflection (3 to 5 lb.) when subject
to finger pressure at midpoint between sheaves.
8. The belt alignment should also be checked to be
sure the belt is running perpendicularly to the rotat-
ing shafts. Fan and motor shafts must be paral-
lel. Improper alignment will result in excessive belt
wear.
9. Check sheave setscrews to ensure tightness. Proper
keys must be in keyways.
10. Do not readjust fan RPM. If sheaves are replaced,
use only sheaves of identical size and type.
11. If unit is to be left idle for an extended period, it is
recommended that belts be removed and stored in
a cool, dry place to avoid premature belt failure.