Bench Testing: Armature

Inspect commutator for dirt or burn spots. See Fig 1 . Correct with sandpaper or lathe as necessary.

NOTE: The following specification presupposes that the armature is free from bend. Bent armature must be replaced.

Check commutator for uneven wear with the armature (1) supported on V-blocks (2). See Fig 2 . If deflection of dial gauge (4) pointer exceeds limit, repair or replace. See STARTER SPECIFICATIONS
Inspect the commutator for wear. See Fig 3 . If diameter is below limit, replace the armature.
Inspect the commutator (1) for insulator (2) depth. See Fig 5 . Correct or replace if it is below the service limit.
Check the commutator and armature core. See Fig 4 . If there is continuity, the armature is grounded and must be replaced.
Check for continuity between segments. See Fig 4 . If there is no continuity at any test point, there is an open circuit and the armature must be replaced.

Fig 1: Inspecting Armature

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Fig 2: Checking Commutator Out Of Round

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Fig 3: Inspecting Commutator Diameter

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Fig 4: Testing Armature For Grounded & Open Circuits

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Fig 5: Inspecting Insulator Depth Of Commutator

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