the springs, if the tension is less than
2 8 ounces.
The generator is a I-pole, shunt-wound, 24-
(3) I n s p e c t the armature windings to see
volt unit with sealed bearings in both the drive
if they are properly pressed in the
end frame and the commutator end frame. The
core slots and tightly soldered to the
generator serves a dual purpose: supplying
c o m m u t a t o r risers.
electrical energy for lights and accessories, and
r e c h a r g i n g the batteries by furnishing current
(4) I n s p e c t t h e c o m m u t a t o r f o r r o u g h
to make up for cranking and other power losses
s p o t s , discoloration, pitting, scoring,
f r o m the batteries while the generator is not
a n d high mica. If the commutator is
in operation. The armature rotates between
rough, pitted, or worn, mount the
the field coils and produces voltage. The gen-
a r m a t u r e in a lathe. Take light cuts
erator is cooled by a fan mounted on the drive
until the commutator is completely
pulley and has clockwise rotation.
cleaned. Remove all burrs by holding
N o . 00 sandpaper lightly against the
commutator while the armature is
50. Generator Assembly Removal
turning on the lathe.
(5) Use a dial indicator to measure the
c o m m u t a t o r - o u t - o f - r o u n d . Repeat the
turning process until it is perfectly
r o u n d and smooth.
b . Disassembly. Refer to figure 16, and dis-
a s s e m b l e the generator.
(6) U n d e r c u t t h e m i c a a f t e r t u r n i n g t h e
commutator. The mica must be under-
cut to a depth of 1/32 to 3/64, inch. If no
51. Generator Assembly Cleaning,
u n d e r c u t t e r is available, use a three-
Inspection, and Repair
cornered file and a piece of hacksaw
a . Cleaning.
blade. Start the groove in the mica
with the file and undercut it with the
( 1 ) Clean all metal parts with the excep-
hacksaw blade. The mica must be cut
t i o n of ball bearing, field windings,
lower than the commutator segments.
and armature, with an approved
Do not leave a thin edge of mica be-
c l e a n i n g solvent and dry thoroughly.
t w e e n any two segments of the com-
(2) Clean the commutator with No. 00
s a n d p a p e r and blow away the parti-
( 7 ) Replace field insulation, if it is broken
cles with low pressure compressed
o r torn.
(8) Test the armature and field coil wind-
( 3 ) Clean the field windings and armature
i n g s (TM 5-764).
with a clean lint-free cloth dampened
( 9 ) Inspect all other parts for worn, dam-
with an approved cleaning solvent.
aged, or defective condition. Replace
b. Inspection and Repair.
or repair worn, damaged, or defective
p a r t s as necessary.
(1) Replace the brushes if they are oil-
soaked, cracked, or worn to one-half
52. Generator Assembly Reassembly
inch in length.
(2) W i t h t h e b r u s h a r m s a n d t h e b r u s h
springs installed, teat for proper
spring tension of 28 ounces. Replace
s e m b l e the generator in the reverse order.