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7000 "A" Frame
To Assemble:
1. Make sure the shaft and keyway are clean and smooth. Clean the
shaft and bore with rubbing alcohol or non oily solvent. Check the
key size with both the shaft and bushing keyways.
2. Put the cap screws through the clearance holes in the bushing and put
the bushing loosely into the impeller, lining up the screws with the
threaded holes on the impeller hub. Do not press, drive or hammer
the bushing into the bore.
3. Start the cap screws by hand, turning them just enough to engage the
threads. Do not use a wrench at this time. The bushing should be
loose enough in the impeller to move freely.
4. Slide the impeller and bushing assembly onto the motor shaft,
ensuring the same distance from the end of the shaft to the bushing as
in step 1 of impeller removal.
5. Fit the key into keyway. Do not force impeller and bushing onto
shaft. If they do not fit easily, check the shaft, bushing and key sizes.
6. Tighten the cap screws progressively with a wrench. Do this evenly
as though mounting an automobile wheel. Turn one a quarter turn,
then the next a quarter turn, then go back and turn the other a quarter
turn and so on. Torque to 10.2 N-m (7.5 ft-lbs.)
7. Peen the end of the motor shaft at the keyway with a chisel or center
punch to prevent the key from falling out of position.
Fan Balance
Fan impellers are statically and dynamically balanced within acceptable
tolerances at the factory. Damage in shipping or from poor handling or
installation may upset the unit's balance. An impeller that is not properly
balanced can lead to excessive vibration causing undue wear on the entire
unit.
If vibration is excessive, shut down the fan and determine the cause.
Common causes of excessive vibration:
Support structure not sufficiently rigid or level. Vibration amplified
by resonance in duct work or support structure.
Bearing locking collar or mounting bolts loose. Impeller or bushing
loose.
Material accumulation on impeller.
Wheel rubbing on inlet ring.
Component Definition and Maintenance
7000A-UM151E-EN-P - October 2018
4-33
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