JLG 1230ES Service Manual - Manual (Page 47)

SECTION 4 - BASE COMPONENTS
3121222 – JLG Lift – 4-11
4.8 WHEEL DRIVE ASSEMBLY - SERVICING
The component parts of the left and right drive motor
assemblies are identical. The left drive motor is run in the
reverse direction of the right motor.
FOR DETAILS ON THE TRACTION SYSTEM ELECTRICAL THEORY
OF OPERATION SEE SECTION 4.
Drive Motor Electrical Evaluation
Several basic electrical tests can be performed on the
Drive Motors. Failure of one of these evaluations is signifi-
cant and may indicate that the device is physically dam-
aged.
Make all measurements with a voltmeter set to resistance
scale (Ohms). Disconnect the Main Battery Disconnect
and all drive motor cables during this analysis.
1. Resistance < 2 Ohms Red to Black Armature
Wires.
The heavy red and black conductors are connected
to the motor's armature winding. The winding is a
very low impedance and should appear to be a
short-circuit for an ordinary voltmeter (other tests
can determine if the armature is truly shorted). High
resistance can signal corrosion, improper crimps,
damaged cabling, worn brushes, a faulty commuta-
tor, or an open armature winding.
2. Resistance < 2 Ohms Blue to Orange Field
Wires.
The blue and orange conductors are connected to
the motor's field winding. In order to make this mea-
surement, it will be necessary to disconnect the butt-
splice on the two orange wires or use a piercing
meter probe. As with the armature, the field is a very
low impedance and should appear to be a short-cir-
cuit for an ordinary voltmeter. High resistance can
signal corrosion, improper crimps, damaged con-
nectors, damaged cabling, or an open field winding.
3. Resistance 15-25 Ohms Yellow to Brown Brake
Wires.
The yellow and brown wires are connected to the
integral brake. Improper resistance can signal cor-
rosion, improper crimps, damaged cabling, or a fault
solenoid.
4. Resistance > 1 mOhm Red Armature Wire to
Motor Housing.
The armature winding should be electrically isolated
from the motor housing. Low resistance may be an
indication of a crushed cable, a burned cable, or a
burned armature winding. Investigate by discon-
necting the drive motor cable from the motor and re-
measure resistance (isolation).
5. Resistance > 1 mOhm Blue Field Wire to Motor
Housing.
The field winding should also be electrically isolated
from the motor housing. Low resistance may be an
indication of a crushed cable, a burned cable, or a
burned field winding. Investigate by disconnecting
the drive motor cable from the motor and re-mea-
sure resistance (isolation).
6. Resistance > 1 mOhm Red Armature Wire to
Blue Field Wire.
The armature and field windings should also be
electrically isolated from one another. Low resis-
tance may be an indication of a crushed cable, a
burned cable, damaged windings. Investigate by
disconnecting the drive motor cable from the motor
and re-measure resistance (isolation).