Doosan DX140LCR, Shop Manual, Page: 176 / 1032

SP001856 Swing Bearing
Page 6
SWING BEARING
MAINTENANCE
Operating Recommendation
The service life of the swing bearing may be extended if a
conscious, daily effort is made to equalize usage over both ends
of the excavator. If the excavator is used in the same operating
configuration day in and day out (for example, with the travel
motors always under the counterweight, or with the attachment
over one side of the machine more than the other), the bearing's
service life could be reduced. Taking a few minutes in the middle
of each work shift to reposition the excavator, to work the
opposite end of the bearing, will provide a payoff in terms of
more even, gradual rate of wear and extended service life.
Measuring Swing Bearing Axial Play
Periodic, regular checks of bearing displacement should be
made at least twice a year. Use a dial indicator. Push the
attachment against the ground to lift the excavator off the ground
and take measurements at 4 points, 90° apart, around the
circumference of the bearing (Figure 1).
Record and keep all measurements. Play in the bearing should
increase minimally from one inspection to the next. Eventually,
however, as the bearing begins to approach the limit of its
service life, clearance increases become much more
pronounced and the actual measured play in the bearing could
exceed twice the value that was measured when the machine
was new.
Measuring Bearing Lateral Play
When vertical checks are made, the side to side play in the
bearing can be checked by fully retracting the arm and bucket
cylinders and extending the tip of the bucket as far forward as it
will go. With the excavator parked on a flat, level surface and the
bucket tip just off the ground, push against the bucket sideways
to take up all of the lateral clearance in the bearing. (Less than
100 lb of force should be required to move the bucket over all
the way.) Check lateral play in both directions and record the
values. When the bearing is beginning to approach the end of its
service life, measured lateral clearance should start to show
larger and larger increases.
1
2
FG000533
Figure 1