SECTION 3 - CHASSIS & SCISSOR ARMS
3-26 – JLG Lift – 3121166
3.5 ELECTRIC DRIVE MOTOR
NOTE: The information contained within this section applies
to the following machines:
USA machines built S/N 0200152825 to S/N
020170585,
Belgium machines built S/N 1200008481 to S/N
1200015159.
DISCONNECT THE BATTERY AND ALLOW THE MOTOR TO COOL
DOWN BEFORE PERFORMING ANY MAINTENANCE. THE SUR-
FACE TEMPERATURE OF THE MOTOR FRAME MAY CAUSE
INJURY TO PERSONNEL.
Disassembly
1. Disassemble the motor from the gearbox.
2. Mark the position of the motor end cap to the motor
shell.
3. Remove the end cap retaining bolt.
4. Remove the retention bolt and washer from the end
of the armature and remove armature from the
motor shell.
NOTE: The load spring that is behind the motor bearing will
be loose when the armature is removed. Take care
not to lose it.
Replacing Motor Bearing
1. Carefully remove the bearing from the armature by
using a bearing puller.
2. Support the armature securely, Using a sleeve
pressing tool or a large socket press the bearing
onto the end of the shaft until it bottoms out on the
shoulder. The pressing tool must touch the bearing
on the inner raceway.
Inspecting Motor Brushes
NOTE: Motor brushes should be inspected every 1000
hours.
1. Loosen the strain relief of the cable and push
approximately 1 in. (25 mm) of cable into the motor.
2. Separate the end piece from the motor shell by
approximately 1 in. (25 mm).
3. Using compressed air, clean the brush housing area
of any accumulated carbon dust.
4. Remove the screw in each of the brush holders that
connects the brush wires.
5. Remove each of the four brushes from the brush
holder.
6. Inspect each brush, if the brush is equal to or less
than 3/8 in. (9.5 mm), the brush will need replaced.
Replacing Motor Brushes
1. When installing new brushes, the motor commutator
must be cleaned to allow for good brush contact. To
do this, mount the armature in a lathe and take a
skin cut on the commutator diameter.
2. Remove any copper chips that may have settled
between the commutator bars.
3. Measure the diameter of the commutator. If the
diameter is less than 2.8 in. (70.5 mm) the commuta-
tor can no longer be used.
4. Measure the depth of the commutator mica (com-
mutator bar insulation). Verify that the depth of the
mica is at least.016 in. (0.4 mm). If the depth is too
shallow, undercut the mica to a maximum depth of
0.048 in. (1.2 mm). After undercut, clean the arma-
ture of any loose mica.
5. Install the new brushes into the brush holders. Make
sure the brush is in the correct orientation to make
smooth contact on the commutator.
6. Connect the brush wires to the terminal on the brush
holder using the bolts that were removed earlier.
7. Pull each brush spring so that it is contacting the
side of the brush. Push the brush springs towards
the outside of each brush box so that the armature
can be reassembled.
Replacing the Motor Cable
1. Using a knife, remove the shrink tubing from the
cable butt splices that stick through a cast hole in
the motor cap end.
2. Mark the brush leads at each splice according to the
color of the cable lead that it is connected to.
3. Cut the leads going into each butt splice.
NOTE: Be sure to cut the leads just below the splice to leave
as much cable as possible.
4. Cut off the motor connector that connects to the
brake.
5. Remove the motor end cap from the motor shell.
6. Using a knife, remove the shrink tubing that is on the
field lead butt splices. There should be 2 splices.
7. Mark the field leads going into each splice accord-
ing to the color of the cable lead.
8. Cut the leads going into each butt splice.
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