TM 55-2925-236-40
Table 3-1. Dental Inspection Requirements - Continued
Fig
Method of Inspection
Nomenclature
Inspection Category
Remarks
Index No.
No.
Visual
Commutator Contact
Surface
Visual
Cracks, Damaged Insula-
tion, Damaged Conduc-
tors
Insulation Breakdown 300
*13700-1C
volts, 60 cps for 1 sec
Between Commutator
Bars and Shaft
(Ground)
*Model 40B
Static and Dynamic
Balance within 0.020
oz in.
Bearing Surfaces
Visual
Housing and Stator
Cracks, Damaged Insula-
53
tion
Bearing Bore Worn
*13700-1C
Insulation Breakdown -
300 volts, 60 cps for 1
sec Between Terminals
and Housing (Ground)
Visual
28
Electrical Contact Holder
Cracks, Distorted Springs
*1106140-3
Spring Pressure to be 46
to 52 oz when Spring is
Just Lifted Beyond
Brush Position
Visual
Insulating Tube
Cracks
33
Visual
End Bell
Cracks, Damaged Threads
34
Bearing Bore Worn
q See tables 21 and 2-2.
Check the drive shaft assembly (22, figure
c. Inspect the commutator of armature assem-
b.
bly (39). The brush contact surface should be
even, high burnished, and dark brown or almost
of new spline teeth are 0.029 inch minimum for
black in color. If the contact surface is rough,
the 16-tooth spline, and 0.039 inch minimum for
pitted, burned, or covered by a hardened film of
the 12-tooth spline. Replace the drive shaft when
carbon or oil which cleaning does not remove,
the "top land" dimension of a spline reaches zero.
resurface the commutator as described in para-
Note. The spline is safe down to a "top land"
dimension of zero, but if service records indicate "top
of component parts. If the inside diameter of
land" dimension may reach zero during the next service
period, the drive shaft should be replaced.
housing and stator (53) or end bell (34, figure
Caution: Spline wear rate will increase
as measured with an air gage, air probe, and
rapidly after reaching the zero "top land" di-
2.0475-inch setting ring, metallize the worn sur-
mension condition.
face as described in paragraph 3-7.
Table 3-2 Fits and Clearances
Mating
Service
Service
Service
Dimensions
Dimensionss
Tolerance
Part No.
(Inches)
Nomenclature
(Inches)
Part No.
Nomenclature
(Inches)
1543957-1
Ball Bearing
0.9843 ID
0.0000 L/L
890659-5
0.9843 OD
Armature
Assembly
1543976
End Bell
2.0475 ID
890659-5
Ball Bearing
2.0470 OD
0.0005 L
Ball Bearing
1543960
8906595
2.0470 OD
0.0005 L
2.4075 ID
Stator
or dry cleaning solvent (item 2, table 23). Do not
3-3. Cleaning
dip parts into the solvent. Use a stiff, non-wire
a. General. Clean all parts of the starter gen-
brush to scrub the parts thoroughly.
erator with trichlorethylene (item 1, table 2-3)
