dry, dip it in clean, light oil to prevent corrosion, and
of the assembly. Slight modifications on the part of
continued contact of unlubricated bearing surfaces. Drain
personnel should be made as necessary to facilitate the
off the excess oil and place bearing in a clean container
work on any particular item.
or wrap until ready for inspection. The following defects
289. Bearings
cannot be rectified and require replacements of the
a. General.
Bearings, when required, must be
bearings.
maintained in proper condition to prevent wear and
(1)
Rust spots on balls or races.
misalinement of moving parts on which they are installed.
(2)
Worn or badly scored surfaces.
shaft but occasionally they may be pressed in the bore of
(3)
Cracked race.
a bearing housing. When removing or installing a bearing
(4)
Defective shield, seal, or separator.
on a shaft, always apply the pressure on the inner race.
(6)
Badly discolored balls or races caused by
When removing or installing in a bore, always apply
overheating.
pressure on the outer race. Do not transmit lateral
pressures through the bearing from one race to another.
(6)
Roughness.
(1)
(7)
Bearing catching at one or more points
of housings whenever possible. Use firm,
caused by damage not by dirt.
steady pressure and do not allow the
(8)
Excessive looseness or end play.
bearing, shaft, or housing to drop on the
d. Installation.
Clean shaft or housing before
floor or ground.
replacing a bearing. Pack the bearing with the proper
(2)
Pulling. Bearings may be pulled if a press
lubricant. Install by pressing, the preferred method, or
is not available.
The puller must be
driving.
arranged to apply pressure on the retained
(1)
Pressing. Apply pressure on the held race
race only.
only. When pressing on a shaft, support
(3)
Driving. Bearings can be removed by
the bearing so that the inner race takes the
driving, using a soft drift carefully placed
pressure. When installing in a housing,
against the held race. Split pipe or tubing
apply pressure against outer race. Use a
with welded lugs can be used to control
suitable mandrel and blocks so that
application of the driving pressure.
pressure is applied evenly around the race.
Alternate the blows on opposite sides of the
(2)
Driving. When a press is not available,
race to prevent wedging the bearing. Be
drive the bearing to its seat by using a soft
careful not to damage splines on the shaft
drift against the held race. Alternate blows
or in the housing.
around the bearing to prevent cocking and
c. Inspection and Repair.
Wipe off as much
possible wedging. Start bearing straight
lubricant as possible. Agitate bearing in clean solvent,
and be careful not to damage shaft or
being careful not to spin the races. Remove bearing from
housing splines.
solvent and flat-slap bearing against a wood block to
(3)
Installation aids. Coating a shaft with white
remove solvent and shake loose any coagulated lubricant.
lead before attempting to install parts will
Place bearing back in clean solvent and continue
prevent binding and simplify installation. If
agitating until all traces of old lubricant is removed.
necessary, heat a very tight fitting bearing
When bearing is clean, remove it from the solvent, shake
to 250F. in a clean oil bath. Always, dry
out as much as possible, and blow dry with compressed
and repack bearings that have been
air directed across the races. As soon as the bearing is
preheated.
AGO 6819A
194
