JLG E300 Service Manual - Manual (Page 62)

SECTION 3 - CHASSIS & TURNTABLE
3-28 – JLG Lift – 3120772
Wear Tolerance
1. With the boom positioned over the side of the
machine, the Upper Boom horizontal with telescope
fully extended and Tower Boom raised half way
(approx 37°)See Figure 2-22, using a magnetic base
dial indicator, measure and record the distance
between the swing bearing and turntable. (See Fig-
ure 2-20)
2. At the same point, with the boom positioned over
the side of the machine, the Upper Boom fully
retracted, the platform rotated max. to the side, and
the Tower Boom fully elevated, (See Figure 2-21)
using a magnetic base dial indicator, measure and
record the distance between the swing bearing and
turntable (See Figure 2-20).
3. If a difference greater than 0.057 in. (1.40 mm) is
determined, the swing bearing should be replaced.
4. If a difference less than 0.057 in. (1.40 mm) is deter-
mined, and any of the following conditions exist, the
bearing should be removed.
a. Metal particles in the grease.
b. Increased drive power.
c. Noise.
d. Rough rotation.
5. If bearing inspection shows no defects, reassemble
bearing and return to service.
Replacement of Swing Bearing
1. Removal.
a. Attach an adequate support sling to the boom
and draw all slack from sling. Prop or block the
boom if feasible.
b. Tag and disconnect hydraulic lines running
through center of turntable and frame. Use a
suitable container to retain any residual hydrau-
lic fluid. Cap lines and ports.
c. Attach suitable overhead lifting equipment to the
base of turntable weldment.
d. 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 bear-
ing upon installation. Remove bolts, nuts and
washers which attach the turntable to the bear-
ing inner race. Discard nuts and bolts.
e. 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.
f. Carefully place the turntable on a suitably sup-
ported trestle.
g. 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 and rotation box assem-
bly from the frame; move to a clean, suitably
supported work area.
h. Remove the two cap screws securing the bear-
ing to the rotation box to separate the two for
inspection.
Figure 3-19. Swing Bearing Tolerance Measuring Point