Swing Bearing; Turntable Bearing Mounting Bolt Condition Check; Wear Tolerance - JLG 600SC Service And Maintenance Manual

3.3 SWING BEARING

Turntable Bearing Mounting Bolt Condition Check

NOTE: This check is designed to replace existing bearing bolt
torque checks on JLG Lifts in service. This check must be
performed after 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 JLG Threadlocker P/N 0100019. After
replacing and retorquing bolt or bolts recheck all existing
bolts for looseness.
1. Check frame to bearing. Attach bolts as follows:
a. Elevate fully retracted main boom to 70 degrees (full
elevation).
b. At the positions indicated on (See Figure 3-10.), try
and insert the 0.0015 inch (0.0381 mm) feeler gauge
between the bolt head and hardened washer at the
arrow indicated position.
c. Assure that the 0.0015 inch (0.0381 mm) feeler
gauge will not penetrate under the bolt head to the
bolt shank.
d. Swing turntable 90 degrees and check some
selected bolts are at the new position.
e. Continue rotating turntable at 90 degrees intervals
until a sampling of bolts have been checked in all
quadrants.
2. Check the turntable to bearing. Attach bolts as follows:
a. Elevate the fully retracted boom to 70 degrees (full
elevation).
b. Try and insert the 0.0015" feeler gauge between
bolt head and hardened washer at position shown
in (See Figure 3-10.).
c. Lower the boom to horizontal and fully extend the
boom.
d. Try and insert the 0.0015" feeler gauge between
bolt head and hardened washer at position shown
in (See Figure 3-10.).
Figure 3-10. Swing Bearing Bolt Feeler Gauge Check
3121776
.0015" Feeler Gauge
SECTION 3 - CHASSIS & TURNTABLE

Wear Tolerance

1. From underside of the machine, at rear center, with the
boom fully elevated and fully retracted, as shown in 
Figure 3-12., Swing Bearing Tolerance Measurement
Location & Boom Placement A, using a magnetic base
dial indicator, measure and record distance between
swing bearing and turntable as shown in Figure 3-11.,
Swing Bearing Tolerance Measuring Point.
2. At the same point, with the boom horizontal and fully
extended, as shown in the Figure 3-12., Swing Bearing
Tolerance Measurement Location & Boom Placement B,
using a magnetic base dial indicator, measure and
record distance between swing bearing and turntable as
shown in Figure 3-11., Swing Bearing Tolerance Measur-
ing Point.
3. If difference is greater than 0.079 inch (2.00 mm), is
determined, the swing bearing should be replaced.
4. If a difference less than 0.079 inch (2.00 mm) is deter-
mined, and any of the following conditions exist, the
bearing should be removed, disassembled, and
inspected for the following:
a. Metal particles in 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 LIFTING ARE CONCENTRATED, AT THE
CENTER OF ROTATION. BECAUSE OF THIS, PROPER MAINTENANCE OF
THESWING BEARING BOLTS IS A MUST FOR SAFE OPERATION.
Figure 3-11. Swing Bearing Tolerance Measuring Point
3-15