9-51
PTT motor
Checking the armature (PTT motor)
1. Check the commutator. Clean using 600-
grit sandpaper and compressed air if
dirty.
2. Measure the commutator diameter “a”.
Replace the armature if below specifica-
tion.
3. Measure the commutator undercut “a”.
Replace the armature if below specifica-
tion.
4. Check the armature for continuity.
Replace if out of specification.
Checking the brush
1. Measure the length of each brush.
Replace if below specification.
2. Check the brush and circuit breaker for
continuity. Replace if there is no continu-
ity.
Do not damage the bimetal “1”. Other-
wise, the operation of the circuit breaker
could be affected.
Motor commutator standard diameter “a”:
22.0mm (0.8661in)
Wear limit: 21.0 mm (0.8268 in)
Motor commutator standard undercut (ref-
erence data) “a”: 1.50 mm (0.0591 in)
Wear limit: 1.00 mm (0.0394 in)
a
a
Armature continuity:
Continuity:
“a”–“b”
No continuity:
“a”–“c”
“a”–“d”
Motor brush standard length “a”:
10.00 mm (0.3937 in)
Wear limit “b”: 3.5 mm (0.14 in)
a
b
c
d
b
a
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