Daewoo Solar 420LC-V, Manual

Page: 13 / 151

Page 12
Hydraulic System Troubleshooting, Testing and
Adjustment
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PILOT PRESSURE
ADJUSTMENT AND TESTING
Vent hydraulic pressure from the reservoir before breaking the seal on fittings to install two in-line "t-style"
adapters and test gauges (60 bar/1,000 psi) at the gear pump outlet port, and at the joystick control valve
pilot line.
Start the engine and turn the engine speed control dial to the maximum setting. After the excavator has
been operated long enough to reach normal operating temperature, back off the engine control dial to
minimum rated RPM speed. With all controls in neutral, make sure the left console control stand is locked
in the down (operating) position and check pressure at the gear pump outlet port and at the joystick.
If gear pump pressure is outside the tolerance specified in the table, adjust gear pump relief pressure by
loosening the lock nut and turning the set screw in (clockwise) to increase pressure, or turning it out to
decrease it.
NOTE:
Be aware that serial number changes and variation in the joystick assemblies used on
different excavators could produce slight change in actual performance characteristics.
Comparison of part numbers to serial numbers stamped on your assembly may be
required, if questions or doubt exists.
WARNING!
This procedure should be done with two people. To reduce the chance of accident or unintended
start-up, one person should remain at the operator’s control stand while checks and
adjustments are made.
IMPORTANT
Top off the hydraulic fluid reservoir if there is any measurable loss of hydraulic oil during test
gauge and adapter fitting installation.
Engine RPM Pilot Pressure @ Pump Pilot Pressure - Joystick
Minimum Speed Setting (full left) on
Speed Control Dial
40 ±5 bar
(580 ±73 psi)
40 ±5 bar
(580 ±73 psi)