d. Exciter Field.
(1) Tag and disconnect exciter field leads at
(2) Raise the brushes from both sliprings and
the exciter commutator.
between exciter leads 104 and 105. If the resistance
is greater than 10 percent above or below 65 ohms,
the field winding is faulty and the field frame must
be removed for further testing.
(4) Use a multimeter to test insulation
resistance between the field and any one of the field
leads. A resistance reading of less than 0.5 megohm
indicates faulty insulation and the field frame must
be removed for further testing.
(1) Tag and disconnect shunt field lead, at
tween leads 101 and 102. A resistance reading of
more than 5 percent above 27.5 ohms indicates a
faulty winding and the field frame must he removed
for further testing.
(3) Use a multimeter to test insulation
resistance between the field frame and any one of
the field leads. A resistance reading of less than 0.5
megohm indicates faulty insulation and the field
frame must be removed for further testing.
3-10. Dynamotor-Welder Work Table
Figure 3-8. Drive belts, removal and installation.
a. Removal. Remove nut, lockwasher and nut
b. Installation. Install in reverse order of
a above.
and van body.
c. Adjustmemt.
b. Installation. Install in reverse order o f
a above.
(2) Hold spring seat in position and turn
3-11. Drive Belts and Shock Absorber
adjusting screw clockwise to raise welder.
a. Removal
(3) Proper belt adjustment is 1 inch deflection
midway between sheaves.
(1) Remove four screws from the milling and
grinding attachment base and remove cover base
(4) Tighten locknut.
(TM 5-4940-225-12).
3-12. Drive Sheave
(2) Remove the two nuts that secure the shock
a. Removal. Remove drive sheave as illustrated
absorber (fig. 2-2) and remove the shock absorber.
(3) Loosen locknut (fig. 2-2) and turn ad-
b. Alignment. Use a straight edge to align
justing screw counterclockwise while holding spring
driven sheave with drive sheave.
seat in position, and lower the welder.
c. Installation. Install drive sheave as illustrated
(4) Remove drive belts from welder and
3-12