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Workman MD/MDXPage 6 -- 22Electrical System
Armature and Field Coil Service (Fig. 24)
IMPORTANT: When removing the commutator end
cover, make sure brushes do not contact the com-
mutator. Damage to the brushes may result.
1. Remove brush covers from the commutator end cov-
er. Lift brush springs from the notch at the end of the
brushes while pulling the brushes out. Allow springs to
hold brushes out from the center (Fig. 25).
2. Remove both through bolts and flat washers s ecur-
ing the commutator end cover to the yoke. Separate end
cover from the commutator and yoke.
3. Separate front end cover from the armature shaft.
A. Remove hex nut, spring washer, pulley, spacer
and woodruff key from the armature shaft.
B. Remove screws, lock washers and flat washers
securing the retainer to the end cover.
IMPORTANT: Use clean, dry, lint--free rags when
cleaning the starter/generator. When using com-
pressed air, air should be filtered and should not ex-
ceed 15 PSI (103 kPa).
IMPORTANT: Remove bearings only if they are to be
replaced. Use proper bearing removal and installa-
tion tools.
4. Clean bearings using a clean cloth. Inspect bearings
for damage. Replace both bearings if either bearing
meets any of the following conditions:
A. Bearings do not spin smoothly, are noisy when
spinning or have excessive end or axial play.
B. The balls or rolling surfaces are pitted or worn.
C. Bearings are rusted, worn, cracked or show ab-
normal color due to overheating.
5. Clean and inspect armature. Replace armature if in-
sulation is burned or charred, wires are broken, shaft is
damaged or bent, armature core lamination is damaged
or solder is thrown.
IMPORTANT: Never use emery cloth on the commu-
tator; short circuiting of the commutator bars may
result. Never use oil or lubricants on the commuta -
tor or brushes.
6. Clean and inspect commutator.
A. Remove carbon dust, dirt and oil from the com-
mutator.
B. Lightly remove slight roughness, burning or glaz-
ing of the commutator with 400 grit (or finer) sandpa-
per. Clean commutator after sanding.
C. Replace armature and bearings if commutator
bars are loose. Raised bars may be reworked (see
Rework Starter/Generator).
7. Measure diameter of the commutator using a mi-
crometer.
A. Measure diameter at two points along the axis of
the commutator and shaft. Measurements must also
be 90
o
apart along the circumference of the commu-
tator.
B. If diameter is less than 1.575 inches (40 mm), re-
place armature and bearings.
8. Clean armature completely with clean cloth and/or
air. Do not use solvent. Make sure slots between com-
mutator bars are free of dust and metal particles.
9. Inspect field coils (Fig. 29).
A. Replace field coils if insulation is blackened,
charred, flaking or cracked.
B. Make sure poles are tight.
1. Armature
2. Commutator
3. Armature shaft
Figure 28
3
2
1