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Page Title:
Figure 29. Testing armature for grounds. |
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 contact surface is rough, pit-
ted, scored, burned, or coated
with hard carbon or oil, the com-
mutator must be resurfaced pro-
vided it is in good electrical
and mechanical condition as a
result of the following inspec-
tion.
Check armature against
limits specified in repair and
rebuild standards (par. 40) and
replace the armature if it is
In-
not within these limits.
spect splines of armature shaft
for wear or damage and replace
the armature if either condi-
tion exists.
Inspect the armature for grounds
(2)
with a test light by touching one
probe to commutator bar riser
and the other to armature core
(fig. 29). Test all commutator
bars in this manner.
If test
light glows, the armature is
grounded and must be replaced.
Inspect armature for short cir-
(3)
cuits with a growler. Place the
armature in the growler and hold
a thin strip of steel, such as
a hacksaw blade, about 1/32 to
l/16 inch away from the armature
core as shown in figure 30.
Testing armature for
short circuits.
While holding the steel strip
in position, rotate the arma-
ture slowly in the growler. A
the
short circuit will pull
steel strip tightly against the
armature core and cause the
If a short
strip to vibrate.
circuit is found, the armature
must be replaced.
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