ELECTRIC STARTER INSPECTION AND
TROUBLESHOOTING
Testing the Armature for Shorts: Place the armature
in the growler and hold a thin steel blade parallel to
the core and just above
it,
while slowly rotating the
armature in the growler (Figure
34).
A
shorted arma-
ture causes the blade to vibrate and move toward the
core.
A
shorted armature must be replaced.
Testing the Armature for Open Circuit: The most
common place for an open circuit is at the commuta-
tor riser bars. inspect conductors for loose connec-
tions at points where they are joined to the commuta-
tor bars.
Testing Commutator Runout: Place the commutator
on a test bench and check runoutwith adial indicator
(Figure 36). When commutator runout exceeds
0.004
inch, reface the commutator.
,
d
FIGURE
34.
TEST FOR SHORTED ARMATURE FIGURE
36.
CHECKING COMMUTATOR RUNOUT
Testing Armature for Grounds: Touch armatureshaft
or core and the end of each commutator bar with
a
pair
of
ohmmeter leads (Figure 35). If the ohmmeter
reading is low,
it
indicates a grounded armature.
Replace a grounded armature.
Testing Armature Shaft Runout: The armature shaft
as well as the commutator may be checked.
A
bent
armature can often be straightened, but if the shaft is
worn a new armature is required (Figure
37).
FIGURE
35.
TEST
FOR GROUNDED ARMATURE
FIGURE
37.
CHECKING ARMATURE SHAFT RUNOUT
Testing Field Coils for Grounds: After unsoldering
the shunt field coil wire, place one test prod on the
connector and the other on a clean spot on the frame.
If
the ohmmeter indicates continuity, the fields are
grounded either at the connector or
in
the windings
(Figure 37a).
4
44
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Redistribution or publication of this document
by any means, is strictly prohibited.
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