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10-30
GENERATING SYSTEM
ELECTRICAL SYSTEMS
(306)
Check armature for short circuits by placing
it on a growler and slowly turning armature
while holding a thin strip of steel (hacksaw
blade) above armature core. The steel strip will
vibrate when above the area of armature core
in which any short circuited coils are located.
Copper or brush dust in slots between commu-
tator bars may cause shorts between bars which
can be eliminated by cleaning out the slots.
Shorts at cross-over of coils at the drive end
can often be corrected by bending the wires
slightly and reinsulating the exposed bare wire.
Test for grounds, using test lamp and points,
by placing one test point on armature core and
the other test point on commutator. If lamp
lights, the armature is grounded. If grounds
are at points where coils come out of slots in
core, repairs can be made by placing insulating
strips between core and coil which is grounded.
If
armature is otherwise satisfactory but
commutator is worn, burned, out of round, or
has high mica between bars, the commutator
should be turned true in a lathe. After turning,
undercut mica
%/ ',
then carefully clean all dirt
and copper dust out of slots. Lightly polish the
commutator with
2/0
sandpaper to remove any
slight burrs left by undercutting operation.
CONNECT
JUMPER-------.
BETWEEN 'F' TERMINAL
AND GROUND
d. Assembly of Generator
Assemble generator by reversing disassembly
procedure. If field coils were removed, use pole
shoe spreader (KMO 579) and pole shoe screw-
driver to install them, to avoid distorting frame
and to insure proper tightening of pole shoe
screws. See figure 10-65.
10-29
TEST AND MINOR ADJUSTMENT
OF GENERATOR REGULATOR-
ON CAR
The generator regulator sh6uld be tested
only when difficulty is experienced in keeping
the battery charged, or when battery uses an
excessive amount of water which is usually
caused by a high charging rate. Before testing
the generator regulator make certain that the
generator and circuit wiring are in good condi-
tion by performing the inspection and test
given in paragraph 10-26.
Each device in the regulator must be tested
separately, in the order given below. The test
equipment specified in each test must be reli-
able and accurate, and a tachometer should be
used to check engine speeds where specified.
IMPORTANT. Mechanical checks and
-ad-
justments (air gap, point opening) must be
made with battery disconnected and preferably
CUT OUT RELAY
(CUT IN)VOLTAGE
~
~
e
,
Figure 10-20-Cutout Relay Test
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