TM11-6125-256-34
(4) Use armature test set TS-965( )/U to check
4-21. Inspection
armature for shorts
a General
(1) After cleaning, inspect the various
(5) Using insulation breakdown test set AN/GSM-6,
subassemblies and detail parts for wear damage, and
apply 300 volts ac 60 Hz, for 1 second between each rotor
deterioration Replace all worn or damaged parts except
assembly (78, fig FO-3) slip ring and the shaft
where a repair procedure is given
(2) Check for stripped or damaged threads Check
(6) Apply 250 volts ac, 60 Hz, for 1 minute between
screws, washers, nuts, retainers, covers, brackets,
a commutator bar and the shaft of armature assembly
housings, terminal blocks, etc, for distortion and wear
(77)
(3) Inspect the electrical components for bums,
cracks, damaged leads or insulation, insecure terminals,
c End Bell and Housing Assemblies Inspect dc end
and other signs of physical damage
bell assembly (66 fig FO-3) ac end bell assembly (67),
and electrical rotating equipment housing assembly (79)
for wear and damage If dc end bearing liner (23, figure 4-
b Armature and rotor Assemblies Inspect armature
8), ac end bearing liner(16, fig 4-9), or dual bearing
assembly (77, fig. FO-3) and rotor assemble (78) as
support (20, fig 4-10) bearing liner is worn, forward the
follows
motor-generator to the depot for repair
(1) Check the banding wires and clips to see that
they are firm and tight Check that commutator bars and
d Spline
slip rings are tight and in alignment Measure the depth of
undercut between commutator bars, the depth should
not be less than 0 021 inch Check for high bars Inspect
(1) Check spline (76, fig FO-3) for wear by
the contact surfaces of the commutator and slip rings,
comparing the old spline with a new spline
which should be even, highly burnished, and copper in
color If the contact surfaces are rough, pitted, scored,
(2) When inspecting for evidence of overheating,
burned, or have a film of carbon or oil that cleaning will
note that although discoloration may indicate
not remove, forward the motor-generator to the depot
weakened spline shaft, the condition can also be present
for overhaul
in a sound shaft Uniform discoloration along the pencil
section of a new shaft may be disregarded However,
localized or blotchy discoloration indicates overheating
NOTE
in service If a slight bluing is present, the shaft may still
Badly burned commutator bars are usually
be serviceable, provided a magnetic particle inspection
the result of open-circuited or shorted
(Military Specification MIL-I-6868) at depot level
armature coils
reveals no surface cracks If black discoloration is
present, discard the spline Conditions which produces
worn spline such as overload and excessive vibration,
(2) Inspect the armature and rotor windings for
should be eliminated
burned, cracked, or frayed insulation Check that all
conductors are firmly brazed to the commutator risers
The depths of the conductors in the armature slots should
e Electrical Components Check suspected electrical
be approximately equal, and each conductor should be
components as described in SECTION VI
firmly fixed in its slot Check for flaring on the
conductors at the drive ends of the core The rotating
field coils should be firmly wedged into the rotor slots,
f AC Stator
with all insulation and taping in place The punchings of
(1) Apply 750 volts ac 60 Hz for 1 second between
the rotating field should be tight
windings A-G B-D and C-F and between each winding
and the yoke
CAUTION
