TM11-6125-256-34
Section IV. MAINTENANCE
CAUTION
3-9. Cleaning
Cleaning of the exterior of the motor-generator is carried
DC brushes are critical items, therefore, use only
out primarily at the Organizational level If such cleaning
brushes specified for use on this equipment Refer
is necessary the procedures in TM 11-6125-256-20
to TM 11-6125-256-34P
should be applied In addition, clean the interior of the
generator section as follows
a. Remove ac and dc brush covers.
WARNING
To be used for cleaning, the compressed
(2) Remove the retaining screws and flat washers
air source must limit the nozzle pressure
from the leads of each of 8 dc contact brushes (2 per brush
to no more than 29 pounds per square inch
holder)
(PSIG). Goggles must be worn while clean-
ing with compressed air.
b. Remove loose carbon dust and dirt
(3) Lift up the brush springs and pull the brushes
from the interior with a stream of dry,
clear of their holders
low pressure compressed air.
c. Replace ac and dc brush covers.
3-10. Replacement of Brushes
(4) Install new brushes by lifting the brush springs
(fig 3-3)
and sliding the new brushes into the holders (2 brushes in
Both ac and dc brushes are replaced at the Direct Support
each holder) The curved face of the brush must fit the
level as described in steps a and b The motor-generator
curve of the commutator Make certain that the brushes
must be removed from the aircraft for brush replacement
slide easily without binding The brush springs must
straddle the brushes without interference from the leads
leads
a AC Brushes
(5) Secure the brush leads to the dc end bell with the
(1) Remove ac brush covers by loosening screws,
screws removed in step (2)
lock washers, and washers
(2) Remove screws, flat washers, and lock washers
(6) Reinstall the dc brush covers
securing each brush lead
c. Brush Run-in and Preseating. Preseat
(3) Raise each brush arm (part of ac end bell) and
and final brush seating must be accomplish
remove brush from brush holder
after the brushes have been installed. Con
the motor-generator (fig. 3-4) and operate
(4) Raise brush arm and slide each replacement
for for two hours each at 1000, 2000, and
brush (4 required) into associated brush holder Lower
volt-amperes. Then operate it for one hour
tension on brush arm
at 3500, 4000, 4500, and 5000 volt-amperes
Check the brush contacts area for shading.
(5) Connect each brush lead with screw, washer, and
shes must be seated as specified in steps
lock washer removed in step (2)
and (2) below. Minor variations in shading
occasionally appear and should be disregar
(6) Reinstall ac brush covers
b DC Brushes
(1) Remove dc brush covers by loosening screws
(1) AC contact brushes 75 percent of brush contact
lock washers, and washers
area
