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d. INSPECTION
• BRUSH LENGTH
Measure the brush length.
If the measurement is less than the service limit, replace the
breaker assembly or brush assembly as an assembly.
• ARMATURE
Check the armature for discoloration or damage, and replace it
with a new one if necessary.
Check the armature shaft for burrs, and correct it with a fine
emery paper if necessary.
Check the commutator surface for rust or damage, and correct
it with a fine emery paper if necessary.
Armature short-circuit test:
Place the armature on a V-block and hold a hacksaw blade
close to the armature core.
Check the armature by turning the core. If the hacksaw blade
attaches to the core or if it vibrates, it indicates the short-circuit
in the armature.
Replace the armature with a new one.
Test without using armature tester:
1) Check for continuity between the segments. If an open
circuit exists between any two segments, replace the
armature.
• If the resistance between the given segments is extremely
low compared to the resistance between the other
segments, there can be a short-circuit between the
segments caused by blockage with brush particles.
Remove the brush particles and recheck. If the resistance
is still extremely low, replace the armature with a new
one.
Standard
Service limit
9.75 mm (0.384 in)
5.5 mm (0.22 in)
514
