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Vertical Drilling Motor, Type GE752, GEK–91584D
15
FIG. 7. DIAGRAM OF CONNECTIONS TO RUN
A SERIES MACHINE FROM A WELDING SET.
E–28718.
leads so machine will operate as a series motor,
and the armature will rotate counterclockwise
(viewed from the commutator end).
Preparation For Operating Shunt Model
Machines For Commutator Resurfacing
1. Break the coupling (if applicable) so the machine
can be run from a d–c power source.
2. Lift all brushes except two of opposite polarity
(adjacent brushholders) which are necessary to
operate the motor.
3. Connect the machine to an outside source of
controlled d–c power, Fig. 8.
4. Apply power as follows:
a. Increase the field supply (0–50 v) to 32.0 volts
at 25 amps.
b. Increase the armature supply (0–150 v) to
150 volts.
c. Slowly decrease the field supply to bring the
speed up to 1000 rpm.
FIG. 8. CONNECTIONS TO RUN A SHUNT
MACHINE FROM A D–C POWER SOURCE.
E–23930A.
NOTE: When shutting down, increase the field
supply to maximum, and then turn off the arma-
ture supply. After the armature supply has been
shut off, shut down the field supply.
Sanding Procedure
If the commutator is dirty, blackened or slightly
rough, resurface it by sanding with 00 sandpaper, or fin-
er, as follows:
1. Attach the fine sandpaper to a wooden block
shaped to fit the commutator, Fig. 9.
2. Run the machine at approximately 1000 rpm and
hold the block against the commutator with a
light, even pressure. Move the block back and
forth longitudinally to clean the commutator.
3. Use clean, dry compressed air, to remove dust
and sand.
Hand Stoning Procedure
If the commutator surface is mildly grooved,
threaded or burned, and only a small amount of copper
has to be removed to correct the trouble, use a hand
stone. Hand stoning will not correct an out–of–round
commutator. See “Fixture Grinding” section.
1. Use a fine–grade stone ground to fit the commu-
tator curvature, Fig. 10. It should also be of suffi-
cient width to bridge any flat spots; otherwise,
the stone will ride in and out of the flat and will not
correct it.
2. Remove one brushholder for access to the com-
mutator.
WOOD BLOCK
SHAPED TO
COMMUTATOR
FINE
SANDPAPER
WOOD SCREW
AND WASHER
FIG. 9. METHOD OF SANDING COMMUTATOR.
E–18149.