Procedural Troubleshooting Baseline Recommendations; Initial Checks And Tests To Establish Operating Condition Of The Excavator - Doosan DX140R Shop Manual

PROCEDURAL
TROUBLESHOOTING BASELINE
RECOMMENDATIONS
Initial Checks and Tests to Establish
Operating Condition of the Excavator
Triage Summary
An excavator that fails to deliver designed performance should
be checked for the following:
• Hydraulic flow, first, and.
• Hydraulic pressure, afterwards, in a specified order of
priority through different points of the system.
To verify adequate available hydraulic flow, before any other
tests are performed through the circuit:
Check engine operation -
• at 1,950 rpm with no load.
• at 1,950 rpm stall load.
If engine rpm drops excessively with a load or fails to surpass
rated speed (1,850 rpm), performance problems may be due to
inadequate hydraulic flow caused by lagging rotational speed.
Verify actual flow on the excavator against rated
NOTE:
performance, with a flow meter.
If engine tests meet specifications and adequate torque and
horsepower are available at the pump drive flex coupling, check
the EPOS trouble codes at display.
Unless any EPOS trouble codes are displayed, check hydraulic
functions in the following sequence:
• Pilot pressure.
• Negacon, negative control pressure.
• Main relief pressure (front and rear pump)
• Swing pressure.
• Port relief pressure (individual control functions;
boom, arm, bucket, swing, and travel)
• Power boost circuit.
• Standard performance
hydraulic motor (travel and swing) speed, cylinder oil
tightness "permissible drift" test.
Hydraulic System Troubleshooting, Testing and Adjustment
Page 14
tests; cylinder speed,
SP001942