SECTION 3 - BASE COMPONENTS
3-8
31215825
Replacing Drive Motor Brushes
THE MOTOR MUST BE DISASSEMBLED FROM THE GEAR
-
BOX AND DISCONNECTED FROM THE MACHINE CONTROL
-
LER BEFORE BEGINNING THIS PROCEDURE.
SEE WHEEL DRIVE ASSEMBLY - REMOVAL FROM MACHINE
AND WHEEL DRIVE DISASSEMBLY - MAIN COMPONENTS
ON THE PREVIOUS PAGES.
1.
Wrap tape around the end of the motor shaft that inter
-
faces with the gearbox to avoid damage to this area.
2.
Remove the motor through bolts.
3.
Remove the motor flange/brake mount from the motor
frame.
4.
Remove the brush housing from the motor frame and
armature by tapping the edge of the brush housing with
a soft-tipped mallet. The brushes will spring towards the
center of the brush housing once it has separated from
the armature.
5.
Remove the wave spring washer from the bearing bore
of the brush housing and set aside.
6.
Pick a brush and remove the screw that fastens its lead
to the brush holder.
NOTE:
If this is a wear indicator brush, then there will be a second
lead that will need to be removed from a spade terminal in
the brush housing.
7.
Remove the brush and brush spring.
8.
Inspect the brush holder for corrosion. Remove any cor
-
rosion that is found.
9.
Install a new brush spring into the brush holder. Make
sure that it is oriented in its correct recoil direction.
NOTE:
The spring contains a flat area with a coil at each end. The
spring should be oriented such that the bend from the flat
area to the coil is towards the brush.
10.
Install a new brush into the brush holder; make sure that
the orientation of the lead wire is the same as the other
brushes.
11.
Push the new brush up into the brush holder. Insert a
pin
(straightened paper clip)
into the small hole in the
brush housing to keep the brush held up in the brush
holder.
12.
Connect the brush lead wire to the brush holder; tighten
to 30 in-lbs. If this is a wear indicator brush, connect the
brush wear indicator lead to the spade terminal in the
brush housing.
13.
Repeat steps 6 to 9 for the other 3 brushes.
14.
Remove the armature from the motor frame by grab
-
bing onto the commutator and pulling it from the motor
frame.
THE PERMANENT MAGNETS IN THE MOTOR FRAME ARE
STRONG AND WILL TRY TO KEEP THE ARMATURE IN THE
MOTOR FRAME. MAKE SURE THAT YOU HAVE A FIRM GRIP
ON BOTH THE ARMATURE AND THE MOTOR FR AME
DURING THIS STEP.
15.
Using compressed air, clean out all of the brush dust
from the armature, motor frame, adapter plate, and
brush holder assembly.
16.
Carefully reinstall the armature back into the motor
frame. So that the commutator end of the armature is at
the end of the frame with the timing marks.
Figure 3-9. Drive Motor - Brush Holder Components
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