JLG 110HX Service Manual - Manual (Page 65)

SECTION 2 - PROCEDURES
3120864 – JLG Lift – 2-41
2.18 SWING BEARING
Turntable Bearing Mounting Bolt Condition
Check
NOTE: This check is designed to replace the existing bear-
ing bolt torque checks on JLG Lifts in service. This
check must be performed after the first 50 hours of
machine operation and every 600 hours of machine
operation thereafter. If during this check any bolts
are found to be missing or loose, replace missing or
loose bolts with new bolts and torque to the value
specified in the torque chart, after lubricating the bolt
threads with loctite #271. After replacing and
retorquing bolt or bolts recheck all existing bolts for
looseness.
Check the frame to bearing. Attach bolts as follows:
1. Elevate the fully retracted boom to 70 degrees (full
elevation).
2. At the positions indicated on Figure 2-15. try and
insert the .0015" feeler gauge between the bolt head
and hardened washer at the arrow indicated posi-
tion.
3. Assure that the .0015" feeler gauge will not penetrate
under the bolt head to the bolt shank.
4. Swing the turntable 90 degrees, and check some
selected bolts at the new position.
5. Continue rotating the turntable at 90 degrees inter-
vals until a sampling of bolts have been checked in
all quadrants.
Check the turntable to bearing. Attach bolts as follows:
1. Elevate the fully retracted boom to 70 degrees (full
elevation).
2. At the positions indicated on Figure 2-15. try and
insert the .0015" feeler gauge between the bolt head
and hardened washer at the arrow indicated posi-
tion.
3. Lower the boom to horizontal and fully extend the
boom.
4. At the position indicated on figure 2-15. try and
insert the .0015" feeler gauge between the bolt head
and hardened washer at the arrow indicated posi-
tion.
Bearing Wear Tolerance
1. From the underside of the machine, at rear center,
with the boom fully elevated and fully retracted (See
Figure 2-15.), measure and record the distance
between the swing bearing and the frame using a
magnetic base dial indicator. (See Figure 2-16.)
2. At the same point, with the boom at horizontal and
extended until red marking band on mid section is
exposed (See Figure 2-6.), measure and record the
distance between the swing bearing and frame
using a magnetic base dial indicator. (See Figure 2-
16.)
3. If a difference greater than 1.625 mm is determined,
the swing bearing should be replaced.
4. If a difference less than 1.625 mm is determined,
and any of the following conditions exist, the bearing
should be removed, disassembled, and inspected
for the following:
a. Metal particles in the grease.
b. Increased drive power required.
c. Noise.
d. Rough rotation.
5. If bearing inspection shows no defects, reassemble
bearing and return to service.
THE SWING BEARING IS ONE OF THE MOST CRITICAL POINTS
ON AN AERIAL LIFT. IT IS HERE THAT THE STRESSES OF LIFT-
ING ARE CONCENTRATED, AT THE CENTER OF ROTATION.
BECAUSE OF THIS, PROPER MAINTENANCE OF THE SWING
BEARING BOLTS IS A MUST FOR SAFE OPERATION.
.0015" Feeler Gauge
Figure 2-15. Swing Bearing Bolt Feeler Gauge Check