(2) Clean field coils with a clean, lint-free
cloth lightly moistened with an approved solvent and
Check diameter of commutator after re-
dry thoroughly with filtered compressed air.
moving material. Diameter shall not be
less than 1.6470 inches.
(3) Remove loose particles from armature
with filtered compressed air and wipe clean with a
cloth lightly moistened with an approved solvent.
(11) Use an ohmmeter to check field coils for
Clean commutator lightly with No. 00 grit sand paper.
insulation breakdown as follows:
Remove all traces of dust with low pressure com-
(a) Attach one lead to field housing and the
other lead to field coil terminal.
and seals with a clean, lint-free cloth lightly moisten-
(b) Replace field coil if a reading of less
ed with an approved solvent.
than 1 megohm is indicated.
(12) Inspect drive assembly for badly worn or
broken teeth. Check internal spline for wear and
damage. Check spring for cracks, breaks, and dis-
Do not allow solvent to contact brushes.
tortion. Replace drive assembly if defective.
(13) Inspect brushholders and support for
(5) Clean brushes with a clean, lint-free
cracks, corrosion, and other damage. Replace de-
(6) Inspect housings and frames for cracks,
(14) Measure brush length. Replace brushes
corrosion, and distortion. Replace defective parts.
if length is 5/16 inch or less.
(7) Inspect bushings for wear, galling, and
(15) Test brush spring tension with a spring
scores. Replace defective parts.
tester. Tension shall be 36 ounces to 40 ounces.
(8) Test armature for grounding as follows:
Replace brush springs if tension is less than speci-
(a) Connect one lead of a test light to the
(16) Inspect all threaded parts for trussed,
stripped or peened threads. Replace damaged parts.
(b) Touch the other test lead to each
across terminals of solenoid frame assembly.
(c) If test light glows, armature is
There shall be no sign of open circuit.
grounded and must be replaced.
(9) Test armature for short circuits as
grounding by touching one lead of ohmmeter to
either lead and the other to the frame casing. There
(a) Place armature on a growler fixture.
(19) Smooth scratches, burrs, and nicks on
(b) Activate the fixture and slowly rotate
any machined surfaces using a fine file. Remove all
armature while touching armature lightly with a steel
filings before reassembly.
(20) Repair minor thread damage using thread
(c) Strip will vibrate against armature
chasers, taps, and dies. Clean threads to remove
over a shorted area.
(d) Replace armature if a short is indi-
(21 ) Remove minor rough spots, scores, and
scratches from bushings using fine crocus cloth or
a fine stone dipped in cleaning solvent. Wash the
(10) Turn down armature if scored or out of
bushings thoroughly in cleaning solvent to remove
round. Under cut mica to a depth of 0.025 to 0.032
all grit and metal particles.
inch below surface of commutator. Use care to avoid
widening commutator slots.