JLG 150HAX ANSI Service Manual - Manual (Page 59)

SECTION 3 - CHASSIS & TURNTABLE
3120679 – JLG Lift – 3-21
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 3-18., Swing
Bearing Bolt Feeler Gauge Check, try and insert the
0.0015" feeler gauge between the bolt head and
hardened washer at the arrow indicated position.
3. Lower the boom to horizontal and fully extend the
boom.
4. At the position indicated on Figure 3-18., Swing
Bearing Bolt Feeler Gauge Check, try and insert the
0.0015" feeler gauge between the bolt head and
hardened washer at the arrow indicated position.
Wear Tolerance
1. From underside of machine, at rear center, with
tower boom fully elevated and fully retracted and
main fully elevated and fully retracted (See Figure 3-
19.), using a magnetic base dial indicator, measure
and record the distance between the swing bearing
and the frame.
2. At the same point, with tower boom at horizontal and
fully retracted and main boom at horizontal and fully
extended (See Figure 3-19.), using a magnetic base
dial indicator, measure and record the distance
between the swing bearing and frame. (See Figure
3-19.)
3. If a difference greater than 0.076 in. (1.93 mm) is
determined, the swing bearing should be replaced.
4. If a difference less than 0.076 in. (1.93 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 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 LIFTING ARE
CONCENTRATED, AT THE CENTER OF ROTATION. BECAUSE OF THIS,
PROPER MAINTENANCE OF THE SWING BEARING BOLTS IS A MUST
FOR SAFE OPERATION.
Replacement and Devcon Application
Procedures
REMOVAL
1. From ground control station, operate tower boom lift
control and raise tower boom adequately to provide
access to rotary coupling.
NEVER WORK BENEATH THE BOOM WITHOUT FIRST PROVIDING
ADEQUATE OVERHEAD SLING SUPPORT AND/OR BLOCKING.
2. Attach an adequate support sling to boom and draw
all slack from sling. Block boom if feasible.
3. From under side of machine frame, remove bolts
and lockwashers which attach rotary coupling
retaining yoke to coupling housing.
HYDRAULIC LINES AND PORTS SHOULD BE CAPPED IMMEDIATELY
AFTER DISCONNECTING LINES TO AVOID THE ENTRY OF CONTAMI-
NANTS INTO THE SYSTEM.
4. Tag and disconnect hydraulic lines from fittings on
top and sides of rotary coupling. Use a suitable con-
tainer to retain any residual hydraulic fluid. Immedi-
ately cap lines and ports.
5. Attach suitable overhead lifting equipment to base of
turntable weldment.
6. Using a suitable tool, scribe a line on inner race of
swing bearing and on underside of turntable. This
line will aid in aligning bearing upon installation.
Remove bolts, nuts and washers which attach turn-
table to bearing inner race. Discard nuts and bolts.
7. Use lifting equipment to carefully lift complete turnta-
ble assembly from bearing. Ensure that no damage
occurs to turntable, bearing or frame mounted com-
ponents.
8. Carefully place turntable on a suitably supported
trestle.
.0015" Feeler Gauge
Figure 3-18. Swing Bearing Bolt Feeler Gauge Check