JLG 15/20MSP Service Manual - Manual (Page 41)

SECTION 3 - BASE COMPONENTS
3121231 – JLG Lift – 3-7
Replacing Drive Motor Brushes
THE MOTOR MUST BE DISASSEMBLED FROM THE GEARBOX
AND DISCONNECTED FROM THE MACHINE CONTROLLER
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
interfaces with the gearbox to avoid damage to this
area.
2. Remove the motor thru 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
corrosion that is found.
9. Install a new brush spring into the brush holder.
Make sure that it is oriented in its correct recoil direc-
tion.
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 thru 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 FRAME 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.
THE PERMANENT MAGNETS IN THE MOTOR FRAME ARE
STRONG AND WILL TRY TO PULL THE ARMATURE IN THE
MOTOR FRAME. MAKE SURE THAT YOU HAVE A FIRM GRIP ON
BOTH THE ARMATURE AND THE MOTOR FRAME SO THAT YOU
CAN CONTROL THE SPEED OF THIS INSTALLATION. BE CARE-
FUL NOT TO PINCH YOUR FINGERS BETWEEN THE ARMATURE
AND THE FRAME.
17. Install the wave spring washer back into the bearing
bore of the brush holder assembly. Make sure that it
is oriented such that the spring touches the outer
raceway of the armature bearing.
Drive Motor - Brush Holder Components