JLG 110HX ANSI Service Manual - Manual (Page 68)

SECTION 2 - PROCEDURES
2-44 – JLG Lift – 3120636
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 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.
Bearing Replacement
1. Removal.
a. From ground control station, operate the boom
lift control and raise boom adequately to provide
access to frame opening or, if equipped, to the
rotary coupling.
NEVER WORK BENEATH THE BOOM WITHOUT FIRST PROVIDING
ADEQUATE OVERHEAD SLING SUPPORT AND/OR BLOCKING.
b. Attach an adequate support sling to the boom
and draw all slack from sling. Block the boom if
feasible.
NOTE: Steps c and d apply to those machines equipped
with a rotary coupling.
c. 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 IMMEDI-
ATELY AFTER DISCONNECTING LINES TO AVOID THE ENTRY OF
CONTAMINANTS INTO THE SYSTEM.
d. Tag and disconnect the hydraulic lines from the
fittings on the top and sides of the rotary cou-
pling. Use a suitable container to retain any
residual hydraulic fluid. Immediately cap lines
and ports.
e. Attach suitable overhead lifting equipment to the
base of the turntable weldment.
f. Use a suitable tool to scribe a line on the inner
race of the swing bearing and on the underside
of the turntable. This line will aid in aligning the
bearing upon installation. Remove the bolts,
nuts and washers which attach the turntable to
the bearing inner race. Discard the nuts and
bolts.

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g. 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.
h. Carefully place the turntable on a suitably sup-
ported trestle.
i. 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 installa-
tion. 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 from the frame; move the
bearing to a clean suitably supported work area.
2. Installation.
NOTE: The following note and steps a thru m pertain to the
use of Devcon and apply only to those machines
built prior to mid-1991.
NOTE: Manufacturing tolerances of frames and turntables
are inspected prior to the factory installation of swing
bearings to determine the need for use of Devcon
filler. When servicing machine swing bearing, apply
Devcon filler only to those machines having Devcon
previously applied at the factory. If new turntable or
frame is being installed contact manufacturer for pro-
cedures to determine the need for Devcon applica-
tion.
a. Use suitable standard tools and equipment to
carefully remove any hardened epoxy residue
from the bearing mounting area of frame and
turntable.
b. Apply a layer of Devcon (or equivalent) filler
approximately 3 mm thick on the bearing mount-
ing plate on the frame.
c. Use suitable lifting equipment to carefully lower
the swing bearing into position on the frame.
Ensure that the scribed line of the outer race of
the bearing aligns with the scribed mark on the
frame (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 frame).
d. Ensure that all frame and bearing attachment
holes are aligned, and install four diametrically
opposed bolts or clamps to secure the bearing
to the frame. Tighten the bolts or clamps evenly
in a diametrical pattern to a torque of 20 ft. lb.
(27 Nm).
e. Allow Devcon filler to cure at room temperature
(approximately 70 degrees F [21 degrees C]) for
10 to 16 hours.