Service and Parts Manual - Cummins Onan

STARTING SYSTEM
ELECTRIC STARTER (Spec A & Spec B)
Normally the starter will require little or no service
other than possible brush replacement. However, if
through accident or misuse, the starter requires service
or overhaul, the following information will provide the
information necessary to perform this service.
STARTER DISASSEMBLY (Figure 16, Spec A; Figure
MA, Spec B)
1. Remove the through-bolts and separate the end
cap, the housing and the armature.
2. Disassemble the drive assembly and the drive end
cap by loosening the self-locking nut.
FIGURE 17. TESTING ARMATURE FOR GROUNDS
FIGURE 16. STARTER DISASSEMBLY (SPEC. A)
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2. Testing Armature for a Short Circuit: Use a growler
for locating shorts in the armature. Place armature
in growler and hold a thin steel blade (e.g. hacksaw
blade) parallel to the core and just above it while
slowly rotating armature in growler. A shorted
armature will cause the blade to vibrate and be
attracted to the core. If armature is shorted, replace
with a new one (FigFe 18).
3. Inspecting For An Open Circuit in Armature: The
most likely place to check for an open circuit is
at the commutator riser bars. Inspect for loose
connections on the points where the conductors
are joined to the commutator bars (Spec A only).
FIGURE 16A. STARTER DISASSEMBLY (SPEC. B)
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HACK SAW
. BLADE i
INSPECTION OF PARTS (Spec A & Spec B)
1. Testing Armature for Grounds: Touch armature
shaft or core and the end of each commutator bar
with a pair of ohmmeter leads. If the ohmmeter
reading is low, it indicates a grounded armature.
Replace grounded armature. See Figure 17.
GROWLER
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FIGURE 18. TESTING ARMATURE FOR SHORT CIRCUITS
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