IV-63
HYDRAULIC UNITS
CONTROL VALVE (HIGH FLOW)
TROUBLESHOOTING
Symptom Probable Causes Remedy
High flow does not oper-
ate.
• The high flow is unloaded (The coil or wiring is
broken.)
• A foreign matter which entered the spool of
the solenoid switching section is blocking the
switching.
• The spool does not operate.
• The spool does not operate (foreign matter en-
tered)
• Replace the coil.
• Clean or replace the spool.
• Check the pressure in the
port PL.
• Disassemble and clean, re
-
pair or replace the spool.
The relief valve cannot
be unloaded.
• The solenoid coil is switched on.
• A foreign matter which entered the spool of
the solenoid switching section is blocking the
switching (the spool does not return).
• A foreign matter which entered the spool is
blocking the spool from returning.
• The plunger is malfunctioning (foreign matter
entered)
• Check the wiring.
• Disassemble and clean, re
-
pair or replace the spool.
• Disassemble to identify the
cause, and repair or replace
the spool.
• Disassemble to identify the
cause, and repair or replace
the plunger.
Oil leakage from sole-
noid valve, cover, or re-
lief valve to the outside.
• Damaged O-ring • Replace
Pressure does not rise. • Catching of foreign matter by the relief valve • Clean or replace.
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