(5) Remove the two grounded brushes (14) from the brush holders on the ommutator head assembly
c
(8).
(6) Remove the two insulated brushes (15) from the frame and field assembly (37).
(7) Remove bearing and felt disk (13) from the commutator head assembly (8).
(8) Remove the four capscrews (32) and lockwashers (31) from the pinion housing (3) and remove the
frame and field assembly (37).
(9) Remove the nuts (19), lockwashers (18), flat washer and insulating washer from the terminal stud
on the frame and field assembly (37).
(10) Remove the thrust washer (12) from the armature (1).
(11) Remove the four flathead screws (27) from the intermediate bearing assembly (7) and remove the
armature (1) from the pinion housing (3).
(12) Bend the lips of the special lockwashers (30) from the special screws (29 and 36) and remove the
special screws and lockwashers from the drive spring (5), drive assembly (4), and drive head (6).
(13) Remove the drive assembly (4), drive spring (5) and drive head (6) from the armature shaft (1).
(14) Remove the intermediate bearing assembly (7), gasket (28) and thrust washer (25) from the
armature (1).
(15) Remove the bearing from the intermediate bearing assembly (7).
(16) Remove the bearing cap (35), bearing (34) and oil seal (33) from the pinion housing (3).
e. Cleaning.
(1) Clean the field coils and armature with a clean cloth dampened with an approved cleaning solvent.
Be careful not to damage the insulation.
(2) Clean remaining parts with an approved cleaning solvent and dry thoroughly with compressed air.
f. Inspection.
(1) Inspect the commutator head for damaged threads, cracks, abrasions, pits, corrosion, distortion,
and other damage. Replace if defective.
(2) Inspect cover band for thrown solder. Inspect armature to make sure windings are pressed into
core slots and are staked and soldered tocommutator risers. If core is scored excessively, replace
the armature.
(3) Place the armature in a padded vise and install commutator head on the armature shaft. Do not
clamp tightly as this distorts the laminations. Check fit of the armature shaft in the bearing by feel.
Excessive side play indicates a worn bearing or a worn armature shaft. Replace as necessary.
(4) Inspect commutator for pits, worn spots and high mica ridges. Remove pits and worn spots with 00
or 000 sand paper. Undercut high mica ridges with an undercutting tool 0.002 inch wider than the
mica. Cut, clean and square to remove all mica to a depth of 1/32 of an inch. Deburr copper after
rushes are seated. Use 00 sandpaper.
(5) To check for out-of-roundness, place armature on V-blocks and put dial indicator against
commutator. Turn armature slowly. Out-of-roundness more than 0.003 of an inch indicates need for
turning on a lathe. Turn the commutator down until all worn or bad spots disappear. Remove burrs
with 00 or 000 sandpaper. Again check run-out. If necessary repeat turning on lathe. Then again
check depth of mica. Repeat undercutting, if necessary.
(6) Inspect the pinion housing for cracks or distortion. Check the fit of the armature shaft in the pinion
housing bearing by feel. Excessive side play indicates worn bearing or worn armature shaft.
Replace as necessary.
g. Testing, Disassembled.
(1) Test armature for shorts by placing it on a growler and holding a thin steel strip lengthwise along
the core 1/2 inch
AGO 6871A
74
