Return to Master Table of Contents Page 27 Hydraulic System Troubleshooting, Testing and Adjustment Problem Possible Causes Remedies 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. 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. 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