JLG 15/20MSP Service Manual - Manual (Page 38)

SECTION 3 - BASE COMPONENTS
3-4 – JLG Lift – 3121231
3.5 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.
Roll And Leak Testing
Torque-Hub units should always be roll and leak tested
before disassembly and after assembly to make sure that
the unit's gears, bearings and seals are working properly.
The following information briefly outlines what to look for
when performing these tests.
NOTE: The brake must be released before performing the
roll test. This can be accomplished by supplying 24
Volts D.C. to the gray 2-pin brake connector.
The Roll Test
The purpose of the roll test is to determine if the unit's
gears are rotating freely and properly. You should be able
to rotate the wheel or hub of the gearbox by hand. If you
feel more drag in the gears only at certain points, then the
gears are not rolling freely and should be examined for
improper installation or defects. Some gear packages roll
with more difficulty than others. Do not be concerned if the
gears in your unit seem to roll hard as long as they roll
with consistency.
The Leak Test
The purpose of a leak test is to make sure the unit is air
tight. You can tell if your unit has a leak if the pressure
gauge reading on your leak checking fitting starts to fall
after the unit has been pressurized and allowed to equal-
ize. Leaks will most likely occur at the pipe plugs, the main
seal or wherever o-rings are located. The exact location of
a leak can usually be detected by brushing a soap and
water solution around the main seal and where the o-rings
or gaskets meet on the exterior of the unit, then checking
for air bubbles. If a leak is detected in a seal, o-ring or gas-
ket, the part must be replaced, and the unit rechecked.
Leak test at 10 psi for 20 minutes.
NOTE: Due the small air volume inside this Torque-Hub, it
will pressurize to 10 psi very quickly. If the pressure
becomes excessive in the unit the seals will be
destroyed.
Oil Type & Capacity
This torque hub unit is shipped with ISO 68 viscosity oil
(hydraulic fluid). It is designed to utilize the same oil
throughout its service life. However, should it need to be
serviced the oil will need to be drained and replaced.
In the event of servicing, fill the unit with ISO grade 68 oil
or oil of a similar viscosity (80W gear oil or 20W engine oil).
The gearbox will need to be filled with 10 oz. of oil.
Oil Filling Instructions
10 oz. of gearbox oil will fill the gearbox cavity approxi-
mately half full. To check the oil level, rotate the wheel so
that the cover plugs are at 12 o-clock and 3 o-clock. Allow
the oil to settle. Slowly loosen the 3 o-clock plug. If oil
begins to come out then the oil level is sufficient. If no oil is
noticed at the 3 o-clock plug location, then remove both
plugs. Slowly add oil at the 12 o-clock plug location until
oil begins to seep out of the 3-clock plug location. Rein-
stall and tighten plugs to 6-8 ft-lbs.
Drive Motor Brush Wear - Warning Indication
The machines drive motors include brush wear sensors
that activate a warning indicating the drive motor brushes
will require replacement soon. This warning protects the
drive motors from damage due to extreme brush wear.
When the brush wear warning is activated the Ground
Control Station LCD screen will indicate a fault code of 6,
also the hour-meter is set to countdown 25 hours of
(DRIVE) operation remaining.
The Platform Control LEDs will indicate this warning with 8
flashing LEDs and an intermittent beep.
Only the drive function when used will affect the hour
meter count down once the warning has been activated.
The machine will operate normally until the last 10 sec-
onds of the 25 hour countdown.
During the last 10 seconds of the 25 hour (DRIVE) count-
down the machine will only drive in creep/turtle drive
mode and platform lift up will be disabled. At this point
cycling power on/off will only repeat the final 10 second
mode cycle.
The machine will not operate normally until the drive
motor brushes are replaced (repositioning the brush warn-
ing sensors), and the Ground Control Station is pro-
grammed to reset the Brush Wear - Warning Timer - see
Section 4.6, Ground Control Module - Programming of
this manual.