Chevrolet 1977 10 Series, Руководство по ремонту, Страница: 225 / 468

ENGINE ELECTRICAL 6D-3
CYLINDER
RETAINER
Fig. 6 D -3S --D rivin g R e ta in e r O ff S nap Ring
turn freely in the overrunning direction and m ust not slip in
the cranking direction. Check pinion teeth to see that they
have not been chipped, cracked, or excessively worn. Check
the spring for norm al tension and drive collar for wear. If
necessary the spring or collar can be replaced by forcing the
collar tow ard the clutch and removing lock ring from end of
tube.
3. Check brush holders to see that they are not deformed
or bent, but will properly hold brushes against the
com m utator.
4. Check the condition of the brushes and if pitted or
worn to one-half their original length, they should be
replaced.
CAUTION:
Some starter motor models use a
molded armature commutator design and no
attem pt to undercut the insulation should be made
or serious damage may result to the commutator.
Undercutting reduces the bonding o f the molding
material which holds the commutator bars and
since the molding material is softer than the copper
bars, it is not necessary to undercut the material
between the bars o f the molded commutator.
5. Check fit of arm ature shaft in bushing of drive
housing. Shaft should fit snugly in the bushing. If the bushing
is worn, it should be replaced. Apply a silicone lubricant to
this bushing before reassembly. Avoid excessive lubrication.
6. Check fit of bushing in com m utator end frame. If this
bushing is damaged or worn excessively, the end frame
assembly m ust be replaced. Apply a silicone lubricant to this
bushing before reassembly. Avoid excessive lubrication.
L ubricant forced onto the com m utator would gum and cause
poor com m utation with a resulting decrease in cranking
m otor performance.
Fig. 6 D -4 S --A rm a tu re S h o rt C irc u it T est
CAUTION:
Some starter motor models use a
molded armature commutator design and no
attempt to undercut the insulation should be made
or serious damage may result to the commutator.
Undercutting reduces the bonding o f the molding
material which holds the commutator bars and
since the molding material is softer than the copper
bars, it is not necessary to undercut the material
between the bars o f the molded commutator.
7. Inspect arm ature com m utator. If com m utator is
rough or out of round, it should be turned down and
undercut. Inspect the points where the arm ature conductors
join the com m utator bars to make sure that it is a good firm
connection. A burned com m utator bar is usually evidence of
a poor connection. See "Turning the C om m utator,"
described under Testing and Repairs.
T E S T IN G A N D R E P A IR S
Armature Test For Shorts
Check the arm ature for short circuit by placing on
growler and holding hack saw blade over arm ature core while
arm ature is rotated (fig. 6D-4S). If saw blade vibrates,
arm ature is shorted. Recheck after cleaning between the
com m utator bars. If saw blade still vibrates, replace the
arm ature.
Armature Test For Ground
Place one lead on the arm ature core or shaft and the
other on the com m utator (fig. 6D-5S). If the lamp lights, the
arm ature is grounded and m ust be replaced.
Field Coil Test For Open Circuit
Place one lead on the insulated brush and the other to
the field connector bar (fig. 6D-6S). If the lamp does not light,
the field coils are open and will require replacement.
Field Coil Test For Ground
N O TE: Be sure to disconnect the shunt coil before
performing this test (when applicable).
Place one lead on the connector bar and the other on
the grounded brush (fig. 6D-7S). If the lamp lights, the field
coils are grounded.
_____...........JS u ,