b. Inspection. Examine gears for cracked, scored,
290. Oil Seals
chipped, or unevenly worn teeth. Examine the gear body
a. General. It is almost impossible to remove an oil
for cracks and warpage. Inspect keyways for good
seal without damaging it. Therefore, if a new seal is not
condition.
immediately available, the old seal should be inspected in
c. Repair. Stone out small scored marks. Replace
place.
gears that have badly worn, chipped or broken teeth.
b. Removal. Seals are removed by prying them out.
Small body cracks can be repaired by welding and
They should then be discarded.
grinding. The heated area should be oil-quenched to
c. Inspection. Examine oil seals and discard if the
maintain their heat treatment. Gear teeth or contact
following defects are observed; damaged case, worn
surfaces should be repaired by welding only if
sealing member, nicked sealing member, distorted inner
replacement parts are not available.
diameter, or incorrectly seated seal.
294. Shims
d. Installation.
New seals should always be
inspected to assure that they are the right size. All burrs
Shims are used to aline and adjust bearings,
or sharp edges should be removed from the shaft to be
bushings, gears, and shafts. Correct interaction of the
sealed and the sealing element lubricated. The seal
machinery components requires the proper contact
should be installed with the wiping edge of sealing
between parts, and this contact can be maintained only by
element toward the lubricant or fluid to be sealed.
shimming as the parts wear. When removing any part
that is shimmed, mark carefully and tie the shims in their
291. Bushings
correct order for proper reassembly. If the shimming
a. Removal and Installation. When disassembling a
requirements of an assembly have changed, adjust the
unit the bushings should be removed with a puller or
shims for the proper operation. Test run the unit after
press whenever possible. This should be carefully done
changing the shims to make certain that the shimming is
so as to not damage the bushings. When installing
correct before locking.
bushings, use a press or drive them in carefully so as to
295. Brake and Clutch Linings
not batter or distort the edges. Align oil holes, if present,
with oil holes in unit. Bushings should always fit tight in
a. General. Brake and clutch linings should be
the housing, so there is no chance of their turning with the
replaced when they are worn to the point that lining rivets
shaft. Be sure they are free of burrs and scratches.
are flush with the surface. Any linings that are oil or
b. Cleaning and Inspection.
Clean bushings
grease soaked should also be replaced. Both halves of a
carefully and inspect for condition. As in the case of
paired lining should be replaced if one-half is worn or
general overhaul it is advisable to replace bushings.
defective.
b. Cleaning and Inspection. If grease or oil is found
292. Shafts
between the lining and housing, take a clean cloth
A drift pin or block of wood should always be used to
dampened with cleaning solvent and force it between the
protect the end of a shaft when it requires hammering to
lining and housing at a point between the live and dead
drive it out or reinstall it. To avoid distortion and damage,
ends. Turn the machinery over several times. Remove
never hammer directly on the end of any part.
the cloth and repeat the operation until the lining is
293. Gears
thoroughly cleaned. If this procedure does not clean the
lining, remove the band and lining and wash the lining
a. General. The same procedures of inspection and
thoroughly with solvent. Examine the lining for excessive
repair apply to all gears used throughout the Crane-
wear, uneven wear, or signs of possible failure. Replace
shovel.
if necessary.
AGO 6819A
195
