between the commutator bars or other causes
which would prevent good contact between
the brushes and commutator.
(f) Low no-load speed and low cur-
(1) The drive, armature and fields
should not be cleaned in any degreasing tank,
due to poor connections, defective leads, dirty
or with grease dissolving solvents, since these
commutator and causes listed under (e).
would dissolve the lubricant in the drive and
(g) High free speed and high current
damage the insulation in the armature and
draw indicate shorted fields.
field coils. All parts except the drive should
be cleaned with oleum spirits and a brush.
lock-torque test requires the equipment il-
The drive can be wiped with a clean cloth.
(2) If the commutator is dirty it may be
current capacity should be used. The cranking
cleaned with No. 00 sandpaper. NEVER USE
motor should be SECURELY mounted and a
EMERY CLOTH TO CLEAN COMMUTA-
brake arm hooked to the drive. When speci-
fied current is applied, the torque can be
f. Inspection and Repair
computed from the reading on the scale. A
(1) Inspect housings and frames for
one foot brake arm will directly indicate foot-
cracks a n d d i s t o r t i o n . I n s p e c t t h r e a d s i n
pound. If the torque is low, the motor must
tapped holes for damage. Replace defective
be disassembled for further tests and repair.
(2) Inspect sleeve bearings for wear. Re-
(1) Scribe marks across drive housing,
place bearing if defective. Check for looseness
fever housing, frame and end ball to facilitate
in housing or end bell. Replace worn or de-
reassembly in the correct relationship.
fective bearings. If new bearing is loose in
bore, replace housing or end bell.
(3) Inspect wicks for tests, fraying, or
wear. Replace if defective.
(4) Turn down commutator if grooved
or out of round. Undercut mica to a depth
of 0.025 to 0.032 inch below surface of com-
mutator. Do not widen slots when undercut-
(5) Inspect drive pinion for broken or
badly worn teeth. Inspect clutch splines for
wear and damage. Inspect shell for cracked
or broken condition. Check to make sure pin-
ion will drive into one direction and will slip
in opposite direction. Replace drive clutch if
(6) Inspect shift lever, shaft, and sole-
noid plunger for cracks or distortion. Replace
(7) Inspect bellows for tears, punctures,
or other damage. Replace if defective.
(9) Inspect brushes for wear or damage.
If damaged, or worn excessively, replace them.
(1) To test armature for grounds or
short, refer to TM 5-764.