Check Points And Solutions For Problems - Doosan DX140R Shop Manual

Check Points and Solutions for Problems

Symptoms
Foreign substance,
dirt, dust in solenoid
valve
Tube or retainer of
solenoid valve
damaged
Malfunction
of solenoid
valve
Coil broken, short, or
burnt
Connector terminal
earth defect
Pilot pressure
Pilot
Pilot relief valve
pressure fails
to generate
Pilot pump
Pilot filter
Pilot system
Poor
Solenoid valve
Actuator
Performance
Main control valve
Other components
Solenoid Valve Assembly
Page 12
Causes
Disassemble the solenoid valve concerned and
check if there are any contaminant such as
foreign substance and sludge between the
caseand the spool.
Disassemble the solenoid valve concerned and
check if there is any deformation (bending or
reduction) in the tube or the retainer.
Disassemble the solenoid valve concerned and
check the resistance of the coil.
Spec : 26.7Ω @ 20°C
Disconnection: ∞
Short: Low or excessive resistance
Disassemble the solenoid valve concerned and
check the outside of the coil to see if its molding is
burnt and melted.
Check if the cap housing (where coil lead is
attached) and the housing (across its length) are
earthed properly.
Remove the plug of the "P5" port, set up a
pressure gage, and check the pilot pressure
discharged from the pilot pump when operating
the cut-off (C1) valve.
Check if the relief valve installed in the pilot line
operates properly.
•
Check if the pilot pump works properly.
Check if the mesh screen of the pilot filter is
contaminated by foreign substance.
Check any defect of the pilot system considering
findings from "Pilot pressure fails to generate"
category.
Set up a pressure gage at each outlet port of the
solenoid valve concerned (HO, TR2, PH, and SP
ports) and check the pressure value discharged
from the pilot pump when operating the solenoid
valve.
Check if main control valve of each component
works properly.
Check if each component works properly.
How to Check
Check if pressure is bypassed due to
the presence of foreign substance.
Solutions
Remove
contaminant,
wash, and
assemble
compartments.
Replace the
solenoid valve.
Replace the coil.
Replace housing
or terminal
concerned.
Refer to Causes
and How to
Check of the
solenoid valve
above.
Remove foreign
substance,
reassemble, and
replace the relief
valve.
Replace the pilot
pump.
Wash,
reassemble, and
replace the filter
Treat defect(s)
accordingly.
Refer to causes
and how to
check of the
solenoid valve
above.
Treat according
to findings.
Treat according
to findings.
SP001944