Return to Master Table of Contents Page 24 Hydraulic System Troubleshooting, Testing and Adjustment TROUBLESHOOTING - SWING GEARBOX Problem Possible Causes Remedies Swing motor fails to operate and: Three pressure tests at motor, brake or makeup valve show low reading(s). Swing relief valve defective Brake release valve defective Motor makeup valve defective. Adjust pressure to recommended range in affected valve. OR Disassemble and clean valve assembly. Replace all valve components that show damage. All three pressure checks are OK but left travel also fails to run. Exchange front and rear pump inlet and outlet hoses to test pump function.
If swing and left travel are restored but right travel stops working, replace or repair P1 pump. All three pressure tests are OK, but machine fails to swing at all. Brake assembly or motor friction plate failing to release. Check for binding. Disassemble and repair. Pilot (control) pressure low or swing control valve stuck. Disassemble / Repair pilot pressure swing spool (305) and / or swing control valve. Swing motor defective. Test motor drain rate. Replace / Repair motor. Gear train defective. Refer to "Swing Gear Troubleshooting" procedure. Swing functions but only at reduced RPM. Causes listed above could also produce dragging swing, OR hot or wrong oil OR worn-out parts.
Check above list; then replace oil, test motor drain rate and check for "02" reading (e-EPOS self-test). Left travel speed is also reduced. Low output at P1 pump or external pilot piping leaks/is clogged. Clean and repair piping or repair or replace pump P1. Swing control movement is reversed. Inlet / outlet piping reversed. Reset controls or reverse piping. Machine swings but continues coasting on past stopping point. Swing control valve spool not centered. Replace return spring; clean/ repair valve piston and spool. Pilot pressure may be outside range. Disassemble, clean or replace pilot relief valve or pilot valve. Swing relief valve may be faulty. Repair/Replace swing relief valve.