balance and will result in damaged battery generator bearings. Check the terminal nuts for corrosion, damage, and
twisted, stripped, or galled threads. Replace damaged or corroded terminal nuts. Inspect the terminal nut washers for
pitting, cracking, etching, and corrosion. Replace damaged, pitted, or corroded terminal nut washers.
d. Cleaning the Commutator.
(1) Insert a piece of No. 00 sandpaper between the brushes and commutator, with the abrasive side against the
(2) Hold the sandpaper against the commutator and slowly turn the armature.
(3) Clean the generator with compressed air and remove all particles of sand from the commutator.
Note. It the commutator is rough or worn, report the condition to the proper authority.
Never oil the commutator.
e. Replacing Brushes.
(1) If the brushes are oil soaked, cracked, or worn down to less than one-half of their original length, they must
(2) Remove the brush lead screw and disconnect the brush lead.
(3) Lift the tension lever and remove the brush.
(4) Install the new brush and see that the beveled edge of the brush is parallel with the commutator segments.
(5) Connect the brush lead and tighten the brush lead screw. Make sure that the brush is not binding in the
holder and that it moves freely.
f. Sanding Brushes.
(1) Cut a strip of 00 sandpaper to match the exact width of the commutator.
(2) Slip the strip under the brush with its abrasive side against the brush.
(3) Hold the sandpaper against the commutator and move the commutator back and forth. Be careful not to
round or break the edges of the brush.
(4) Clean the commutator, brush, and tension lever with clean compressed air.
g. Testing Brush Spring Tension.
(1) Hook a spring scale in the hole at the end of the tension lever.
(2) Pull the scale in a straight line outward from the commutator center and take the reading just as the tension
lever starts to leave the brush. Be careful to exert the pull in the same plane as the plane of the brush face.
(3) The proper brush spring tension is 37 to 44 ounces. Bend the spring to increase or decrease its tension.