JLG M600 Service Manual - Manual (Page 70)

SECTION 3 - CHASSIS & TURNTABLE
3-32 – JLG Lift – 3121813
3.8 SWING DRIVE
Roll, Leak and Brake 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 and hydraulic lines to
motor removed before performing the roll test.
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 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
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.
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 air checker 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 loca-
tion 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.
BRAKE TEST
The brake test should be performed prior to disassembly
and after reassembly to ensure that the brake functions
properly and does not leak. The brake test procedure can
be found in the Motor-Brake Subassembly section of this
manual.
NOTE: Failure to perform this test may result in damaged or
ineffective brake parts.
Tightening and Torquing Bolts
If an air impact wrench is used to tighten bolts, extreme
care should be taken to ensure that the bolts are not tight-
ened beyond their specified torque.
The following steps describe how to tighten and torque
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. Crisscross around the bolt circle and tighten remain-
ing bolts.
4. Now use a torque wrench to apply the specified
torque to bolt "A".
5. Using the same sequence, crisscross around the
bolt circle and apply an equal torque to the remain-
ing bolts.
Motor Control Valve Disassembly
1. Place unit on bench with the motor end up.
2. Remove Hydraulic Tubing Assembly (20) by loosen-
ing Fittings (18) on both ends of tube with a wrench.
NOTE: Items (18) & (19) are included on Item (20) when
ordering a replacement Tubing Assembly.
3. Using a wrench, loosen jam nut on Elbow Fitting
(17) and remove fitting from Motor Control Valve
(31).
4. Using a wrench, remove Fitting (21) from Brake
Housing.
5. Remove Motor Control Valve (31) from Motor (10) by
removing the four Bolts (34) and washers (33).