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1.Support the armature with
a pair of V block and turn it to measure the runout of the
surface not rubbed by the brushes using a dial
gauge. Standard value: 0.05 mm or
less Limit: 0.1 mm
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2.Measure the diameter of
the commutator. Standard value: 29.4
mm Limit: 28.8 mm
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3.Measure the depth of the
undercut between segments. Standard value: 0.5
mm Limit: 0.2 mm
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Push the brush into the brush
holder to make sure that the spring is working on the
brush. If the spring is not working, replace the brush
holder.
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1.Make sure that the pinion
cannot be turned anti-clockwise and can be turned clockwise
freely. 2.Check the pinion for abnormal ware and
damage.
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1.Check the commutator
contacting surface of each brush for abnormal roughness.
Also check the height of the brush. Replace the brush holder
if the height is lower than the limit. Limit:
10 mm 2.When the contact surface of the
brush is rectified or the brush holder is replaced,
recondition the contact surface with sandpaper wrapped
around the commutator.
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1.Check the armature coil
for short circuit as follows.
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2.Set the armature in a
growler.
caution |
Clean the surface of the
armature thoroughly before performing the
test.
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3.While holding a thin strip of iron against
the armature in parallel with its axis, turn the armature
slowly. The armature is normal if the iron strip is not
attracted to the armature or it does not vibrate.
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4.Check the insulation
between commutator segments and armature coils. The armature
coils are properly insulated if no continuity is
present.
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5.Check continuity between a
segment and another. There is no open circuit in the tested
coil if there is continuity.
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