MK Plastics Axijet IO&M - Manual (Page 12)

Page12
Bearing Replacement
The fan bearings are pillow block ball bearings (Axijet 1225 & 1500 models have flange bearing assemblies). An
emery cloth or file may be needed to remove imperfections in the shaft left by the setscrews.
NOTE: In applications where contact with the contaminated exhaust surface poses a health hazard, the bearings
can be removed with the wheel and inlet cone staying in place. In this case, the shaft must be held in place with
suitable straps or bracings firmly secured around the bearing support frame. The shaft must be supported to re-
strict any lateral movement of both shaft and impeller. In this case, review but skip steps 2, 4, 6, & 14 .
1. Mark the position of the shaft of both bearing races, setscrews, and the wheel and pulley.
2. Mark the location and orientation of the inlet cone. Note the clearance between the wheel and the inlet
cone.
3. Remove the fan pulley.
4. Remove the inlet cone. Remove the wheel from the shaft – a 2-jaw puller may be needed.
5. Remove bearing hold-down bolts.
6. Remove shaft and bearings as one unit.
7. Remove anti-corrosion coating from the shaft with a suitable degreaser.
8. Remove the bearing from the shaft using a bearing puller. If a bearing puller is not available, tap on the
bearing with a wood block and hammer to remove it.
9. Smooth and clean the shaft and bearing bore thoroughly.
10. Place the bearings into position making sure they are not on a worn section of the shaft. Tapping the
inner ring face with a soft driver may be required. Do not hammer on the housing.
11. The outer ring of the bearing is spherical and swivels in the housing to compensate for misalignment.
Secure hold down bolts, but do not fully tighten.
12. Align the setscrews on the bearings and tighten one setscrew on each bearing.
13. Rotate the shaft to allow the bearing outer rings to find their center of free movement.
14. Install the wheel on the shaft. Install the inlet cone in its original location. And adjust bearing
position and inlet cone to center the wheel in the inlet cone.
15. Tighten the hold-down bolts to proper torque.
16. Turn the shaft by hand. Resistance should be the same as it was before the hold-down bolts were fully
tightened.
17. Tighten the bearing setscrews. Refer to torque chart on Page 9.
18. Re-install the pulley and adjust the belt tension.
19. Test run and retighten all setscrews and hold-down bolts; trim balance as necessary (.0785 in/sec max.)
After 24 hours of operation, retighten the setscrews to the appropriate torque. Make sure the socket key or driver
is in good condition with no rounded corners. The key should be fully engaged in the setscrew and held squarely
to prevent rounding out of the setscrew socket when applying maximum torque.
Fig. 14 - Bearing Assembly