Swing Bearing; Swing Bearing Wear Tolerance - JLG 400SC Service And Maintenance Manual

3.5 SWING BEARING

Swing Bearing Wear Tolerance

See Figure 3-49., Swing Bearing Wear Tolerance.
1. Position the machine as follows and as seen in
Figure 3-49., Swing Bearing Wear Tolerance, Position 1:
a. The turntable needs to be centered between the
rear wheels.
b. Lift the boom to horizontal and fully extend the
main boom
c. Lift the jib to be horizontal
d. Keep the jib and platform centered and unloaded
2. Set up a dial indicator as follows:
a. The dial indicator location is to be at the front center
of the machine, next to the bearing, opposite of the
tower pivot pin.
b. The magnetic base of the indicator should be posi-
tioned on the frame
c. The indicator point needs positioned to measure
the turntable base plate 2 in. (51 mm) from the root
of the gear tooth. Refer to Figure 3-49., Swing Bear-
ing Wear Tolerance.
3. Zero the dial indicator.
4. Check dial indicator accuracy once positioned, using a
feeler gauge and ensure the dial indicator reading, is the
same as the feeler gauge thickness.
5. Position the machine as follows and as seen in
Figure 3-49., Swing Bearing Wear Tolerance, Position 2:
a. Do not rotate the turntable
b. Raise the main boom to be fully elevated and
retracted
c. Raise the jib to be fully elevated and centered
d. Center the platform and keep it unloaded
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SECTION 3 - CHASSIS & TURNTABLE
6. Verify the dial indicator has not shifted. Record the value
for bearing play.
7. Return the machine to Figure 3-49., Swing Bearing Wear
Tolerance, Position 1. The dial indicator should to return
to zero. If the dial indicator does not return to zero, take
corrective action and repeat the test.
8. If the measurement is more than 0.10 in. (4.2 mm),
replace the bearing. If the measurement is less than
0.10 in. (4.2 mm), and any of the following conditions
exist, the bearing should be removed, disassembled,
and inspected.
a. Metal particles in the grease.
b. Increased drive power required.
c. Noise.
d. Rough rotation.
9. If bearing inspection shows no defects, reassemble and
return to service.
3-49