JLG 4394RT Service Manual - Manual (Page 63)

SECTION 3 - CHASSIS, PLATFORM & SCISSOR ARMS
3121249 – JLG Lift – 3-27
3.4 DRIVE HUB (FAIRFIELD)
Roll and Leak Testing
Always roll and leak test Drive-Hubs after assembly to
make sure that the unit’s gears and sealants are working
properly. The following information briefly outlines what to
look for when performing these tests.
THE ROLL TEST
The purpose of a roll test is to determine if the unit’s gears
are rotating freely and properly. You should be able to
rotate the gears in your unit by applying a constant force
to the roll checker. If you feel more drag in the gears only
at certain points, then the gears are not rolling freely and
you should examine them 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 air checker starts to fall once you
have pressurized the unit. Leaks will most likely occur at
the main seal or wherever o-rings or gaskets are located.
Usually you can detect the exact location of a leak by
brushing a soap and water solution around the main seal
and where o-rings or gaskets meet the exterior of the unit,
then checking for air bubbles. If you detect a leak in a
seal, o-ring, or gasket, replace the part immediately.
Tightening and Torquing Bolts
If you use an air impact wrench to tighten bolts, take
extreme care to ensure that you do NOT tighten the bolts
beyond their indicated torque specification. Never use an
impact wrench to tighten shoulder bolts. Always tighten all
shoulder bolts by hand.
The following steps describe the proper procedure for
tightening and torquing bolts or socket head cap screws
in a bolt circle.
1. Tighten (but do not torque) bolt ”A” until snug.
2. Go to the opposite side of the bolt circle and tighten
bolt ”B” until equally snug.
3. Continue around the bolt circle and tighten the
remaining bolts.
4. Now use a torque wrench to apply the specified
torque to bolt ”A”.
5. Continue around the bolt circle and apply an equal
torque to the remaining bolts.
Oil Information
1. TYPE – EP90
On normal applications, use EP90. On applications
where the lubricant must meet special requirements,
the O.E.M. should be able to recommend a suitable
substitute.
2. OIL TEMPERATURE
Continuous – 160°F [70°C] Intermittent – 200°F
[95°C]
3. OIL CHANGE
Initial – After 50 hours or 50,000 revolutions of oper-
ation. Subsequent – After 1000 hours or (1) year,
whichever comes first.
NOTE: Higher temperatures make it necessary to change oil
more frequently.
4. OIL FILL LEVEL AND VOLUME
Unit mounted horizontal – half full
Approximate volume - 17 oz. (0.5 ltr)
5. REAR BRAKES
Rear brakes require 2.7 oz. (0.08 ltr) of DTE 13M
hydraulic fluid each to function properly.
“A”
“B”