9-S15
B1710 · B2110 · B2410 · B2710, WSM
ELECTRICAL SYSTEM
(3) Servicing
Commutator and Mica
1. Check the contact face of the commutator for wear, and grind the
commutator with emery paper if it is slightly worn.
2. Measure the commutator O.D. with an outside micrometer at
several points.
3. If the minimum O.D. is less than the allowable limit, replace the
armature.
4. If the difference of the O.D.’s exceeds the allowable limit, correct
the commutator on a lathe to the factory specification.
5. Measure the mica undercut.
6. If the undercut is less than the allowable limit, correct it with a saw
blade and chamfer the segment edges.
W10170920
Brush Wear
1. If the contact face of the brush is dirty or dusty, clean it with emery
paper.
2. Measure the brush length (A) with vernier calipers.
3. If the length is less than the allowable limit, replace the yoke
assembly and brush holder.
W10175440
Brush Holder
1. Check the continuity across the brush holder and the holder
support with an ohmmeter.
2. If it conducts, replace the brush holder.
W10176720
Commutator O.D.
Factory spec.
28.0 mm
1.102 in.
Allowable limit
27.0 mm
1.063 in.
Difference of O.D.’s
Factory spec.
Less than 0.02 mm
0.0008 in.
Allowable limit
0.05 mm
0.0020 in.
Mica undercut
Factory spec.
0.60 mm
0.0236 in.
Allowable limit
0.20 mm
0.0079 in.
(1) Segment
(2) Undercut
(3) Mica
(a) Correct
(b) Incorrect
Brush length (A)
Factory spec.
14.0 mm
0.551 in.
Allowable limit
9.0 mm
0.354 in.
Resistance
Brush holder –
Holder support
Infinity
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