JOHNSON CONTROLS
55
SECTION 4 – MAINTENANCE
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
4
Fan Shaft Bearings
General –
When removing and replacing the bearings,
care should be taken to ensure that the area where the
bearings fit on the shaft does not become scored or
damaged. The shaft in this area should be thoroughly
cleaned before the bearing is removed and again before
the new bearing is installed.
Mounting Details
1. Check the shaft. It should be straight, free of burrs
and full size. Be sure the bearing is not seated on
a worn section of shafting.
2. Make certain any set screws are not obstructing
the bearing bore.
3. Align the bearing in its housing and slide the bear-
ing into position on shaft (never hammer the ends
of the inner race). If necessary, use a brass bar or
pipe against the inner race to drift bearing into
place (never hit the housing, as bearing damage
may result). Make sure there is lubricant between
the bearing outer ring and the housing.
4. Fasten the bearing housing to the unit mounting
support with hex head cap screws, washers, new
lock washers and hex nuts before securing the
bearing to the shaft. This permits the bearing to
align itself in position along the shaft and elimi-
nates any possibility of cramping loads.
5. Rotate the shaft to make certain it turns freely.
6. Bearings may employ one of several different
methods to lock the bearing to the shaft.
Shaft should be free from burrs. If old
shaft is used, be sure a ball bearing is
not seated on worn section and shaft is
not bent.
There are various degrees of self-alignment in bear-
ings of the same manufacturer. The force required
for the self-alignment of the bearings used in YORK
manufactured units has been specified and is closely
monitored at the factory. If it is necessary to purchase a
bearing locally, be sure it can be worked around in the
housing with a short shaft made of wood or other soft
material placed in the bearing.
Prior to installing the bearing on the shaft, it should be
worked around in the housing to make sure that self-
alignment is obtained where the bearing is installed.
After the shaft journal has been inspected for cleanli-
ness, metal chips or burrs, the bearing is slipped, not
forced, onto the shaft. Forcing the bearing onto the
shaft by the use of flange, pillow block, or outer ring
will damage the bearing internally. Force applied in
this way transmits the load to the inner race through
the balls in the bearing. Since the bearings are not de-
signed for axial loading, the sides of the races in which
the balls turn can be damaged. If the bearing cannot
be made to slip onto the shaft by pressing on the inner
ring of the bearing, check the shaft for burrs. Install the
bearing so the part of the inner race, which receives
the locking collar or contains setscrews, is toward the
outside of the unit.
If the grease fitting must be changed on bearings that
utilize a locking pin under the fitting, it is important
to properly replace it. If an adapter or grease fitting of
improper size and length is used, the locking pin may
be either too tight or loose and can affect the alignment
and re-lubrication of the bearing.
Bearing Lock Devices
Various types of locking devices are used to secure
bearing(s) to the fan shaft.
Refer to the instructions
packed with bearings for special information.
is a typical bearing with a setscrew-
type locking device. The various locking devices can
be classified under basic types: eccentric locking type,
concentric locking type, and Skwezloc type.
FIGURE 21 -
BEARING WITH SETSCREW TYPE
LOCKING DEVICE
00418VIP
Seal
Lube
Fitting
Lock
Ring
Pillow
Block
Inner
Race
Outer
Race
Set
Screws
