JLG 660AJ Service Manual - Manual (Page 87)

SECTION 3 - CHASSIS & TURNTABLE
3121616 – JLG Lift – 3-43
Swing Bearing Replacement
REMOVAL
1. Operate boom from Ground Control station to provide
access to frame opening or rotary coupling.
NEVER WORK BENEATH THE BOOM WITHOUT FIRST ENGAGING BOOM SAFETY
PROP OR PROVIDING ADEQUATE OVERHEAD SLING SUPPORT AND/OR BLOCK-
ING.
2. Attach an adequate support sling to boom and draw all
slack from sling. Prop or block boom if feasible.
3. From inside turntable, remove mounting hardware
attaching rotary coupling retaining yoke brackets to
turntable.
HYDRAULIC LINES AND PORTS SHOULD BE CAPPED IMMEDIATELY AFTER DIS-
CONNECTING LINES TO AVOID THE ENTRY OF CONTAMINANTS INTO THE SYS-
TEM.
4. Tag and disconnect hydraulic lines from fittings on top
of rotary coupling. Use a suitable container to retain any
residual hydraulic fluid. Immediately cap lines and ports.
5. Attach suitable overhead lifting equipment to base of
turntable weldment.
6. Use a suitable tool to scribe a line on swing bearing
inner race an underside of turntable. This will aid in
aligning bearing upon installation. Remove bolts and
washers which attach turntable to bearing inner race.
Discard bolts.
7. Use lifting equipment to carefully lift complete turnta-
ble assembly from bearing. Ensure no damage occurs to
turntable, bearing, or frame-mounted components.
8. Carefully place turntable on a suitably supported trestle.
9. Use a suitable tool to scribe a line on outer swing bear-
ing race and frame. This line will aid in aligning bearing
upon installation. Remove bolts and washers which
attach outer race of bearing to frame. Discard bolts. Use
suitable lifting equipment to remove bearing from
frame, then move bearing to a clean, suitably supported
work area.
INSTALLATION
1. Using suitable lifting equipment, carefully lower swing
bearing in position on frame. Ensure scribed line of
outer bearing race aligns with scribed line on frame. If a
new swing bearing is used, ensure filler plug fitting is
90° from fore and aft center line of frame.
JLG INDUSTRIES RECOMMENDS ALL REMOVED BEARING BOLTS BE DISCARDED
AND REPLACED WITH NEW BOLTS. SINCE THE SWING BEARING IS THE ONLY
STRUCTURAL LINK BETWEEN THE FRAME AND TURNTABLE, IT IS IMPERATIVE
SUCH REPLACEMENT HARDWARE MEETS JLG SPECIFICATIONS. USE OF GENU-
INE JLG HARDWARE IS HIGHLY RECOMMENDED.
2. Apply a light coating of Loctite #271 to new bearing
bolts, and loosely install bolts and washers through
frame and outer race of bearing.
IF COMPRESSED AIR OR ELECTRICALLY OPERATED IMPACT WRENCH IS USED
FOR TIGHTENING THE BEARING ATTACHMENT BOLTS, THE TORQUE SETTING
ACCURACY OF THE TOOL SHOULD BE CHECKED PRIOR TO USE.
3. Refer to Torque Sequence diagram as shown in Figure 3-
60., Swing Bearing Torque Sequence. Clean residue off
new bearing bolts, then apply a light coating of Loctite
#271 and install bolts and washers through frame and
outer bearing race. Torque bolts to 190 ft-lb (258 Nm).
Remove lifting equipment from bearing.
4. Using suitable lifting equipment, carefully position turn-
table assembly above machine frame.