Doosan DX225LC-3, Shop Manual

Page: 289 / 878

SP002535
Page 17
Hydraulic System Troubleshooting, Testing and Adjustment
POWER MODE VALVE
Current Signal and Hydraulic Pressure
Adjustments
The electromagnetic pressure proportioning control (EPPR)
"power mode" valve is on the underside of the pumps (not visible
in the harness connections drawing, because it is underneath
the assembly), near the engine/pump flexible coupling, adjacent
to the pump return line. To test and adjust power shift current
and pressure through the power mode valve a multilead jumper
harness is required. The jumper harness (which is available
through DOOSAN After Sales Service, or could be spliced
together from commonly available, purchased parts) has extra
leads so a VOM meter can be connected to the circuit. To set up
the testing equipment, stop engine and disconnect the single
electrical lead from the power mode valve. Attach the jumper
harness to the terminal on the valve, connect the test leads of
the multimeter to the extra leads on the harness and reconnect
the valve electrical lead.
Vent the lever on top of the hydraulic tank to relieve pressure
and connect an in-line "T-style" adapter to the valve pressure
port. Install a 60 bar (1,000 psi) test gauge in the adapter.
Restart the engine and increase engine rpm by turning the
speed control to the maximum speed setting. Warm up the
engine and hydraulic system until hydraulic oil temperature is at
least 45°C (113°F). Select Power Mode on the Instrument
Panel. Check current readings (in milliamps) on the VOM meter
and hydraulic pressure gauge readings and make sure both
conform to the values in the table below.
NOTE:
If recorded values do not conform to the specified
current or pressure in the table, back off the locknut
on the end of the valve, turn the adjusting screw 1/4
turn and recheck current and pressure. Repeat
adjustment as required to obtain specified
performance and retighten the valve locknut.
WARNING
AVOID DEATH OR SERIOUS INJURY
This procedure should be done with two people. To reduce
the chance of accidental movement of the excavator, one
person should be properly seated at the operator's controls
while checks and adjustments are made.
Mode Engine rpm Current Pressure
Power Plus
Mode
High Idle:
1,890 (Auto Idle OFF)
1,800 (Auto Idle ON)
200 ± 20 - 650 ± 65 mA
Midrange value corresponding to
engine rpm for both current and
hydraulic pressure readings.
1.6 - 32.8 kg/cm
2
(22.9 - 466.5 psi)
Power Mode High Idle: 1,700 240 ± 23 - 650 ± 65 mA 3.8 - 32.8 kg/cm 2 (54 - 466.5 psi)
Standard
Mode
High Idle: 1,650 280 ± 28 - 650 ± 65 mA
6.4 - 32.8 kg/cm
2
(91 - 466.4 psi)
Economic
Mode
High Idle: 1,600 340 ± 34 - 650 ± 65 mA
10.6 - 32.8 kg/cm
2
(150.8 - 466.5 psi)