17
Laboratory Exhaust Systems
®
The intent of this fan design with its large side access
openings is to allow a field service technician to replace
bearings with the fan remaining in place in its intended
application. All work can be conducted by accessing
the bearings through the blower housing side access
openings. This procedure assumes power source has
been locked out prior to removing guards and covers,
belts and pulleys have been loosened and removed
properly and extended lubrication lines have been
disconnected at the bearing. In some cases it may be
necessary to remove the motor and mounting plate.
Belt Drive
This procedure assumes proper safety measures have
been taken and the driven sheaves and belts have
already been removed. Shaft black coating can be
removed with a solvent similar to brake cleaner. Read
through these directions completely prior to starting this
procedure.
1. Scribe line at the top of both the top and bottom
bearings. These marks are used to locate the proper
mounting position for the new bearings
2. Loosen and remove top bearing from fan shaft. Use
spanner wrench or blunt punch to loosen bearing.
Follow bearing manufacturer’s instructions on
removal. An emery cloth may be required to clean
and remove burrs off shaft. Finish removing top
bearing.
3. Install two shaft
collars flush with
the top support
plate to hold and
support the shaft
when removing
bottom bearing.
4. Loosen bottom
bearing. Caulk
seal may need
to be broken
around perimeter
of flange housing and bottom support plate. Use
emery cloth to clean shaft and remove any burrs.
5. Install second set of shaft collars flush with top of
bottom support plate.
6. Remove shaft collars on top support plate and
finish removing bottom bearing.
7. Install new bottom bearing in reverse of this
procedure. Remember to re-install top set of shaft
collars prior to removing lower shaft collars.
Top
Bearing
Support
Plate
Bottom
Bearing
EQUIPMENT REQUIRED
• Four shaft collars
• Emery cloth
• Caulk
• Replacement bearings
• Spanner wrench and sockets
8. Align the top of the bearing with the scribed mark
indicating the correct mounting location. Secure
lower bearing to bottom support plate. Do not
secure the bearing to the fan shaft.
9. Turn the wheel approximately 20 – 30 rotations
to allow the shaft to properly set in the bottom
bearing.
10. Finish installing bearing on fan shaft according
to bearing manufacturer’s installation procedure.
Rotate the wheel again for 20 rotations. If resistance
is felt the bearing did not set properly. Reset the
shaft in the bearing.
11. Remove top set of shaft collars and install top
bearing according to bearing manufacturer’s
instructions making sure the top of the bearing
lines up with scribed mark indicating the correct
mounting location.
12. Connect extended lube lines to new bearings. Zerk
fittings from old bearings may need to be installed
in replacement bearings
13. Reinstall drive sheave and belts. Check for
alignment.
14. Caulk around bottom bearing flange for an
improved water tight seal.
Bearing Replacement
