Daewoo Solar 300LC-V, Manual

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S0702170K
Page 28 Hydraulic System Troubleshooting, Testing and
Adjustment
TROUBLESHOOTING – CONTROL VALVE
Check control valve problems only after other hydraulic circuit operational tests have been made. Refer to
the “Troubleshooting Baseline Recommendations” procedure. Pump flow, pilot pressure, Negacon
pressure, main relief pressure, and port relief pressure should all be checked before starting to work on the
control valve. Make sure the hydraulic system is topped up to the required level and free of oil leaks or air
in the system that could cause cavitation problems.
Swing motor operates unevenly. Swing gear, bearing or mounting
loose or worn. Repair or replace.
Lubricant worn away,
inadequate. Grease.
Swing relief valve may be faulty. Repair/Replace the swing relief
valve.
Problem Possible Causes Remedies
Main Relief Valve Particulate contamination. Disassemble, clean main
poppet.
Broken or damaged spring. Replace.
Adjusting screw loose. Readjust.
Main poppet sticking. Repair/replace.
Clogged orifice in pilot passage
to control valve. Clean/replace.
Cylinder goes down in spool
neutral. Excessive clearance between
casing and spool. Replace spool or casing.
Spool does not return to neutral/
sticking spool. Check secondary pilot pressure.
Spool does not return to neutral
because of dirt or other
contaminants. Clean.
Broken or damaged spring. Replace.
Main relief or port relief not
operating properly. See above.
Impurities in pilot circuit. Clean.
Cylinder drops before start at
boom up operation Rod check valve damaged or
clogged. Clean/replace.
Poppet sticking. Clean/replace.
Broken or damaged spring. Replace.
Slow operation or response Excessive clearance between
spool or casing. Check pilot pressure and/or
replace spool or casing.
Sticking spool. Clean/replace.
Broken or damaged spring. Replace.
Main or port relief valve
damaged. Check pressure/replace.
Problem Possible Causes Remedies