JLG 80HX, Service Maintenance Manual

Page: 67 / 120

SECTION 2 - PROCEDURES
3120863 – JLG Lift – 2-45
Wear Tolerance
1. From the underside of the machine, at rear center,
with the boom fully elevated and fully retracted (See
Figure 2-29.), using a magnetic base dial indicator,
measure and record the distance between the swing
bearing and frame. (See Figure 2-29.)
2. At the same point, with the boom at horizontal and
fully extended (See Figure 2-29.), using a magnetic
base dial indicator, measure and record the distance
between the swing bearing and frame. (See Figure
2-31.)
3. If a difference greater than 1.45 mm is found, the
swing bearing should be replaced.
4. If a difference less than 1.45 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
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.
Swing Bearing Torque Values
1. Outer Race - 235 NM wet, 304 NM dry.
2. Inner Race - 235 NM wet, 304 NM dry.
3. Swing Bearing Torquing Sequence, see Figure 2-32.
RETORQUE THE INNER AND OUTER SWING BEARING BOLTS
AFTER FIRST 200 HOURS OF OPERATION, AND EVERY 500
HOURS THEREAFTER.
Figure 2-31. Swing Bearing Tolerance Measuring Point