Doosan DX480LC - Inspection; Testing; Troubleshooting, Testing and Adjustment

SP001620Center Joint (Swivel)
Page 8
TROUBLESHOOTING, TESTING
AND ADJUSTMENT
Inspection
The center joint should be checked for evidence of external oil
leakage every 2,000 operating hours. Leaking or defective O-
rings are an indication that dirt and other contaminants could be
getting inside the assembly, which will promote accelerated,
abnormal wear and may cause early failure of the assembly.
If internal seals or other sliding surface components are worn
and there is internal fluid leakage, complete overhaul and repair
or replacement of the center joint may be required.
Testing
To check pressure through the center joint, make up a test kit
from the following equipment list:
• 700 bar (10,000 psi) pressure gauge.
• Adapters, connectors, piping and flange block-off
plates conforming to those used in high-pressure
piping connections of the excavator.
• A high-pressure relief valve with a setting pressure
1.5 times maximum system pressure.
• A stop valve.
• A manually operated, in-line changeover valve.
Install the changeover valve upstream from one of the stem
high-pressure ports. Connect the pressure gauge downstream
from one of the body ports. Install the stop valve between the
changeover valve and the stem of the center joint. Other
components should be installed according to the layout in the
block diagram. The test kit is used to pressurize the center
swivel above normal working pressure and lock in the higher
pressure (as the stop valve is closed manually) for a leak down
test.
NOTE: The same type of kit can also be made up for the
drain port (return line) side of the center joint. Use
appropriate piping, connectors, test gauges, etc., and
follow the same block diagram general layout (Figure
2).
Pressure
Gauge
Swivel Joint
Body (Outer)
Swivel Joint
Stem (Inner)
Stop
Valve
Manually-Operated
Changeover Valve
High Pressure
Pump
Tank
Relief
Valve
(1.5x)
0370
Figure 2