JLG 3246ES Service Manual - Manual (Page 69)

SECTION 3 - CHASSIS & SCISSOR ARMS
3121166 – JLG Lift – 3-33
NOTE: Reference Figure 3-29., Drive Motor Components for
part names and locations when servicing the Drive
Motor.
Periodic maintenance consisting of inspections of
motors, batteries and wiring circuitry is recommended.
CAUTION
ALWAYS WEAR EYE PROTECTION DURING ANY MAINTENANCE
OPERATION.
Drive Motor Troubleshooting
1. Turn off power to unit and disconnect main bat-
tery power. Disconnect drive motor connections
from the Power Module.
2. Verify field continuity between the blue and
orange wires. If available, use a 4-wire ohmmeter
to verify the field resistance per the applicable
motor specification below.
3. Verify armature continuity between the red and
black wires. If available, use a 4-wire ohmmeter to
verify the field resistance per the applicable motor
specification below.
4. Using a dielectric tester, verify that there are no
shorts between the following items:
a. Field connector pins and the case of the motor.
b. Armature terminals and the case of the motor.
c. Field connector pins to the armature terminals.
5. Verify continuity in 2 pin brake connector (yellow
and brown wires). Measure the brake resistance
and verify that it is between 18 and 22 Ohms.
Drive Motor Disassembly
NOTE: Refer to Figure 3-29.
1. Remove the two Cover Plate Mounting Screws (14)
holding the Cover Plate (13) in place and remove
the cover plate from the motor.
2. Remove the Brake Cover Mounting Screws (15)
holding the Brake (11) in place and set aside. These
screws are used to manually release the brakes.
3. Remove the two Terminal Cover Mounting Screws
(16). Slide the strain relief of the Wire Harness (1)
out of the cover and remove the cover from the
motor.
4. Discard the Gasket (12) that was located under the
brake and terminal covers.
5. Remove the wire harness from the motor by dis-
connecting the brake connection and armature
connections. Cut the field connection close to the
crimp connection on the motor side.
6. Install the two Brake Cover Mounting Screws (15)
into the threaded holes in the brake assembly and
tighten to manually release the brake (see Figure
3-10.).
7. Remove the three screws holding the brake
assembly to the motor. Carefully remove the brake
assembly, brake disc and reaction disc from the
motor by sliding off of the shaft.
8. Remove the screws holding the Commutator End
Head (9) in place and remove the commutator end
head from the frame and field assembly. The
Armature (2) will be attached to the commutator
end head.
9. Pull back the Brush Springs (4) in the commutator
end head, pull the brush back and rest the springs
on the side of the brush. The brushes should move
freely within the holders.
10. Use an arbor press or a bearing puller to remove
the armature from the commutator end head
assembly.
11. Remove the Snap Ring (7) and Bearing (8) from the
commutator end head. Discard the bearing.
Drive Motor Inspection and Service
NOTE: Refer to Figure 3-29.
1. Carefully blow out any accumulated carbon dust
and dirt from the Commutator End Head (9) and
the Frame & Field Assembly (2) using clean, oil free,
compressed air.
2. Replace Brushes (5) that are worn below their
usable length of 0.6 in (1.5 cm), show signs of
uneven wear or signs of overheating, such as dis-
colored brush shunts and brush springs. Brushes
should always be replaced in complete sets of four.
Use identical replacement parts; do not substitute
brush grades as the brushes are matched to the
motor type and application to provide the best
service. Substituting brushes of the wrong grade
can cause premature commutator failure and
excessive brush wear.
3. Make sure the Brush Box Assembly (6) is tight on
the commutator end head. Replace brush box
assemblies in the commutator end head if they are
physically damaged or brush holders are loose on
the brush plate.
4. Visually inspect the frame and field assembly for
overheating or other signs of damage. Check all
wiring to ensure that the insulation is in good con-
Model
Field Resistance @
75°F (24°C)
Armature Resistance
@ 75°F (24°C)
1930ES 0.21 Ohms 0.037 Ohms
2030ES/2630ES/2646ES/
3246ES
0.127 Ohms 0.051 Ohms