Doosan DX480LC - Cautions for Operation; Functions and Operation

SP000192
Page 7
Breaker EPPR Valve (Opt)
FUNCTIONS AND OPERATION
The proportional reducing valve shall be adjusted that its
reduced pressure is proportional to the current of the solenoid.
The proportional solenoid shall be changed with pressure
proportional to the electrical input signal. Flow increases
corresponding to the force of the solenoid. As the solenoid (1)
receives pressure, the spool (4) opens and oil flows from P to A.
Pressure of the port A influences the top surface of the pin (5).
When it reaches the valve set of the solenoid, the spool starts to
move and oil flow from P to A decreases.
CAUTIONS FOR OPERATION
1. Wiring of the solenoid
• The solenoid has no polarity.
2. Input electricity
• Do not supply electric current more than 0.7A to the
solenoid coil.
3. Adjustment screw
• It was adjusted to the standard.
• The pressure of the port A increases when turning
the adjustment screw clockwise.
4. Symptoms and Solutions of Problems
Symptoms Causes Solutions
Pressure does not
increase nor change
Poor wiring Fix wiring
Solenoid damaged Replace the solenoid
Piston or spool sticked Fix, or clean and grind
Amplifier damaged Repair or replace the amplifier
Unnatural pressure
change
Poor opening space
Too wide
Too narrow
Readjust
Piston or spool sticked Fix, or clean and grind
Unnatural pressure
Poor opening space
Too wide
Too narrow
Readjust
Slow reaction Low pressure supplied Readjust