JLG E300 Service Manual - Manual (Page 40)

SECTION 3 - CHASSIS & TURNTABLE
3-6 – JLG Lift – 3121253
3.3 DRIVE HUB
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.
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 gears in your unit by applying con-
stant 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 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 (MAIN UNIT)
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
equalize. Leaks will most likely occur at the pipe plugs,
the main seal or wherever o-rings or gaskets 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 gasket,
the part must be replaced, and the unit rechecked.
Leak test at 10 psi for 20 minutes.
Main Disassembly
1. Perform Roll Check and Leak Check if applicable
prior to disassembling the unit.
2. Drain oil from unit. Note the condition and volume of
the oil.
3. Remove Coupling (7) from Spindle End first.
4. Remove Retaining Ring (6G) by prying the open end
of Retaining Ring out of the groove in the Ring Gear
(1F) with a screwdriver, then grasp the loose end
with pliers and pull the Retaining Ring completely
out of the groove.
5. Remove the Cover Subassembly (6) from the unit.
The unit can be carefully pressurized with air to pop
the cover out of the unit. Washer (2) may have to be
removed separately because of the loose attach-
ment.
6. Remove the First Stage Sun Gear (10) if applicable.
NOTE: On units with ratios greater than 36:1 numerically,
there will not be a separate First Stage Sun Gear
(10), as the gear teeth will be integral to the Input
Shaft (9).
7. Remove the Input Carrier Sub-assembly (3). Contin-
ued on next page.
8. Remove the Second Stage Sun Gear (11).
9. Remove the Input Shaft (9).