JLG 460SJ Service Manual - Manual (Page 98)

SECTION 3 - CHASSIS & TURNTABLE
3-46 – JLG Lift – 3120895
Replacement of Swing Bearing
Removal of the swing bearing is as follows:
1. Attach an adequate support sling to the boom and
draw all slack from sling. Prop or block the boom if
feasible.
2. Tag and disconnect hydraulic lines running through
center of turntable and frame. Use a suitable con-
tainer to retain any residual hydraulic fluid. Cap lines
and ports.
3. Attach suitable overhead lifting equipment to the
base of turntable weldment.
4. Use a suitable tool to scribe a line on the inner race
of the swing bearing and on the underside of the
turntable. This will aid in aligning the bearing upon
installation. Remove bolts, nuts and washers which
attach the turntable to the bearing inner race. Dis-
card nuts and bolts.
5. Use the lifting equipment to carefully lift the com-
plete turntable assembly from the bearing. Ensure
that no damage occurs to the turntable, bearing or
frame mounted components.
6. Carefully place the turntable on a suitably supported
trestle.
7. Use a suitable tool to scribe a line on the outer race
of the swing bearing and the frame. This line will aid
in aligning the bearing upon installation. Remove the
bolts and washers which attach the outer race of the
bearing to the frame. Discard the bolts. Use suitable
lifting equipment to remove the bearing and rotation
box assembly from the frame; move to a clean, suit-
ably supported work area.
8. Remove the two capscrews securing the bearing to
the rotation box to separate the two for inspection.
Installation of the swing bearing is as follows:
1. Install bearing to turntable with two capscrews, so
that fill plug of bearing is as close to gear as bolt pat-
tern will allow. Do not tighten capscrews.
2. Line up high spot (yellow) of bearing with center
tooth of bull gear. Set backlash to 0.008 - 0.010 inch
(0.20 - 0.25 mm). Tighten capscrews as shown in
Figure 3-33., Swing Bearing Torque Sequence
3. Grease bearing with Mobilith SHC Bearing Grease.
Grease fitting is on inside wall of inner race of bear-
ing.
NOTE: If Mobiletac 375NC is not available, Tribol Molub-
Alloy 936 Open Gear Compound or Mobilith SHC
Bearing Grease or Multi-Purpose Grease (MPG) can
be substituted, however the service interval will be
shorter.
4. Using suitable lifting equipment, install bearing/
assembly to frame with soft spot (red) 90 degree rel-
ative to load axis. If reusing old bearing, ensure that
scribed line of outer race of the bearing aligns with
the scribed mark on the frame.
JLG INDUSTRIES RECOMMENDS THAT ALL REMOVED GRADE 8
BEARING NUTS AND BOLTS BE DISCARDED AND REPLACED
WITH NEW GRADE 8 NUTS AND BOLTS. SINCE THE SWING BEAR-
ING IS THE ONLY STRUCTURAL LINK BETWEEN THE FRAME AND
TURNTABLE, IT IS IMPERATIVE THAT SUCH REPLACEMENT
HARDWARE MEETS JLG SPECIFICATIONS. USE OF GENUINE JLG
HARDWARE IS HIGHLY RECOMMENDED.
5. Apply a light coating of Loctite 271 to the new bear-
ing bolts and loosely install the bolts and washers
through the 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.
6. Following the torque sequence diagram shown in
Figure 3-33., Swing Bearing Torque Sequence,
tighten the bolts to an initial torque of 130 ft. lbs.
(175 Nm). Then following the same sequence,
tighten to a final torque of 190 ft. lbs. (260 Nm).
7. Remove lifting equipment from bearing.
8. Use suitable lifting equipment to carefully position
the turntable assembly above the machine frame.
9. Carefully lower the turntable onto the swing bearing.
Ensure that the scribed line of the inner race of the
bearing aligns with the scribed mark on the turnta-
ble. If a new swing bearing is used, ensure that the
filler plug fitting is at 90 degrees from the fore and aft
centerline of the turntable.
10. Apply a light coating of Loctite 271 to the new bear-
ing bolts and install through the turntable and inner
race of bearing.
11. Following the torque sequence shown in Figure 3-
33., Swing Bearing Torque Sequence tighten the
bolts to an initial torque of 130 ft. lbs. (175 Nm).
Then following the same sequence, tighten the bolts
to 190 ft. lbs. (260 Nm).
12. Remove the lifting equipment.
13. Route hydraulic lines through center of turntable and
frame and connect as tagged prior to removal.