OMM-11-0211-page 12
To balance a blower wheel:
1. Add balancing weights for fabricated aluminum, steel or stainless steel wheels:
Balance weights should be rigidly attached to the wheel at a location that will not interfere with the blower hous-
ing nor disrupt air flow. They should (if at all possible) be welded to the wheel. When trim balancing the wheel,
on the blower shaft
,
be sure to ground the welder
directly
to the wheel. Otherwise, the welding current will likely
pass through the blower shaft and damage the blower and/or motor bearings.
NOTE:
Removing any Backward Inclined or Airfoil wheel requires special attention when reinstalling it. Make sure you
reinstall the wheel so the proper wheel-to-inlet bell clearance is maintained. Failure to do this will affect the blow-
er’s airflow (
CFM
), and/or static pressure (
SP
) capabilities and efficiency.
See Table 1 on page 4.
Consult
Cincinnati Fan or our local sales office for your area for assistance if necessary.
D. Vibration:
As mentioned previously in this manual, excessive vibration can cause premature motor and/or blower bearing failure that
could lead to catastrophic failure of the blower. After performing any routine maintenance, the vibration readings should be
taken again. New readings should be taken (maximum every 12 months) and compared to the readings you recorded in
Fig. 8
, on page 9, during the initial startup.
If any major differences are present, the cause should be determined and
corrected before the blower is put back into operation.
The most common causes of vibration problems are:
1. Wheel unbalance
4. Poor blower inlet and/or discharge conditions
2. Bearing failure
5. Foundation stiffness
3. Mechanical looseness
6. Misaligned sheaves and/or belts
E. Blower Shaft & Bearing Replacement:
The blower shaft and bearings for Cincinnati Fan blowers are carefully selected to match the maximum load and operating
conditions for each specific blower model. If the instructions in this manual and those provided by the bearing manufacturer
are followed, you should not need to replace the bearings for many years.
When you do need to replace the bearings, it is strongly recommended that the blower shaft also be replaced at
the same time.
Use the following applicable steps when replacing the blower bearings and/or blower shaft.
1. LOCK OUT THE POWER SOURCE TO THE MOTOR AND LET THE WHEEL COME TO A COMPLETE STOP.
2. Remove the inlet bell.
3. If necessary, disconnect the optional blower housing.
4. Measure the location of the blower wheel on the shaft.
Record the dimension.
5. Remove the locking hardware in the wheel hub.
6.
Carefully
remove the wheel.
7. Remove the belt guard and open the shaft/bearing access hole covers in the side of the base.
8. Loosen (but don't remove) the 4 bolts in the side of the motor adjustment base.
9. Loosen the belt tension by turning the 4 bolts in the top of the motor adjustment base.
10. Remove the belt(s).
11. Loosen the blower sheave set screws, or taper-lock hub bolts, and remove the blower sheave.
12. Disconnect the lube lines to the blower bearings.
13. Remove the 4 bolts holding the two bearings on the bearing base.
Be careful not to change the location of any bearing
riser shims that might be under the bearings.
14. Remove the shaft and bearing assembly from the blower.
15. There is a rust preventative coating that was applied to the blower shaft before shipment. Remove this coating at all areas
on the shaft with a solvent or degreaser.
WARNING:
DO NOT use gasoline to remove this coating.
CAUTION:
Use gloves to protect your skin.
16. Measure
(and record)
the distance between the bearings and the distance from each bearing to each end of the shaft.
17. Remove the hardware holding the bearings on the shaft and then, remove the bearings from the shaft.
18. When replacing the bearings, we strongly recommend that you also replace the blower shaft.
However, if you intend to
use the same shaft, file down all set screw marks on the shaft from the bearings, blower wheel or sheave.
19. If you are replacing the blower shaft, it should be turned, ground and polished shaft material. It should be the same length
and diameter and have the same keyway sizes and lengths on both ends of the shaft.
20. Install new bearings onto the new or original blower shaft.
Be sure the bearing locking collars are facing each other
and the set screws in the locking collars are in line with each other. DO NOT tighten the locking collars onto the
shaft at this time.
NOTE: If you are replacing “split housing” type bearings, refer to the bearing manufacturers directions for proper
mounting and adjustment.
21. Place the shaft and bearing assembly onto the blower bearing base with any bearing riser shims located under each bear-
ing as were under the original bearings in Step 13 above.
22. Install the hardware to hold the bearings to the bearing base.
DO NOT tighten the hardware at this time.
