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LUBRICARE AND BEARING SERVICE
BEARING SERVICE
1-13
1-14 INSPECTION OF BEARINGS
AFTER CLEANING
Most ball and r
oller bearings
fail from pre-
ventable
cau
ses.
When
bea rings
are inspected
after
cleaning and
f
ound to be unfit for further
service,
the caus
e
of
failure
should be deter-
mined in
or der
to a
void
r
epetition of failure
when ne
w bearings
are
installed.
Bearings r
otated by
hand for internal
inspec-
tion should be under enough axial pressure to
bring balls or roll
ers
firml
y
into contact with
race-ways. In case of single row angular con-
tact bearings,
pressure
must always be applied
on the
thrust faces
of races.
Single row radial bearings normally have a
certain amount of
looseness
or end play which
•
is easily felt when dismounted. Single row
angular contact bearings are ver y loose when
dismounted
and
this
greater looseness
must not
be mistaken for
wear.
Double row angular contact bearings are
preloaded or
made t
o minus end play and there-
fore should
have
no end
play
that can be dis-
tinguished by hand feel.
Carefully
inspect
bearings
in a good
light,
discarding bearings which show any of the
following defects:
a. Cracked
race.
Forcing a cocked bearing
on or off a shaft will do
this,
as will too heavy
a press fit.
b.
Rusted balls, rollers, or
raceways. Usually
caused by water passing worn or
defective
seals
or by
condensation
inside housing.
c.
Worn,
galled,
or
abraded surfaces.
Can be
caused by too
loose
fit or adjustment, or bear-
ing locked by dirt and turning on shaft or in
housing.
d.
Broken
or
bent
shie lds, seals, or sepa-
rator. Usually caused by improper use of tools
during installation or
removal.
e. Badly discolored
balls,
rollers, or races.
Usually due to inadequate supply of lubricant
or improper type of lubricant. NOTE: Mod-
erate
discoloration of bearing parts is not cause
for
discard.
f. Flat spots
on
rollers.
Usually caused by
improper fit
or wrong lub r icant
.
g.
Extrem e
roug
hness.
Roughn ess
following
thorough cleaning and oiling indicates damage
to
raceways,
balls or rollers such as indenting
by dirt or metal particles, or pitting by corro-
sion. Very slight roughness from light indenta-
tions seldom affects the bearing life and is no
cause for
disca rding
bearing. Extremely rough
bearings will be noisy in operation and may
soon fail in
service,
therefore they should be
discarded.
h. Rough
or
"catchy" f
eeling
at one or more
points.
A rough or
"
cat ch y" feeling at one or
'mor e points as bearing is rotated indicates
spalled or
chipped
spots due to fatigue or shock.
Thorough
flushing is necessary
to make certain
this condition is not caused by dirt or metal
particles.
i. E
xcessive looseness
or end play. Excessive
looseness or end play is caused by lapping of
bearing parts by abrasive material in the lubri-
cant. Races and
balls
or rollers are dull gray
wh
en
lapped by
abrasive
material. Any loose-
ness or end
play
in a double row bearing which
can be detected
by
hand
feel
is cause for dis-
carding
bearing.
E
xcessive looseness in a single
row radial ball
bearing
is cause for rejection;
if in doubt, che
ck against
feel of identical new
bearing.
!' . .
ngular cont a ct ball or roller bearings
usually can
be
ad
justed
during installation to
take care of a reasonable amount of wear due
to lapping action of abrasive material in lubri-
cant
;
however, an excessively worn bearing
should be
discarded .
1-1 5 CARE OF CLEANED AND
NEW BEARINGS
a.
Cleaned Bearing s.
Bearings that are sat-
isfactory
for
further use after cleaning and
inspection must
be carefully
protected to avoid
damage or contamination with dust or other
abrasive
substances.
Immediately
after inspect ion, thoroughly oil
bearings to
prevent
rust and place them in a
clean,
covered
container or wrap them in clean
oiled paper until
ready
for installation. Dry
paper, if used for wrapping, will absorb oil
from bearing and
promote
rust.
Avoid handling bearings more than abso-
lutely necessary. Even when coated with oil, a
bearing can become rusted in a comparatively
short time by contact with the salty moisture
deposited by the
fingers.
b.
N
ew
Bearings.
Store ne
w bearings in a
place
that
can be
kept
re
a sonably clean and not
subject
to
extremes
of
heat or moisture which
would
promote
rusting or deterioration of bear-
ing
lubricants.
In order to minimize possibility
or rusting or lubricant aging in storage, always
use the
oldest
bearings in stock first.
Keep bearings sealed in original containers-
don't open containers and handle bearings. If
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