Troubleshooting Swing Function Failure on the Hitachi EX60-2 Excavator

[MikePhua]

The EX60-2 and Hitachi’s Compact Excavator Legacy
The Hitachi EX60-2 is part of the EX-series compact excavators that helped define the brand’s reputation for reliability and hydraulic finesse in the 1990s. Built for urban construction, utility trenching, and light demolition, the EX60-2 featured a robust hydraulic system, a swing priority valve, and a compact tail design that made it ideal for tight spaces. With an operating weight of approximately 13,000 lbs and a 4-cylinder Isuzu diesel engine producing around 50 hp, the EX60-2 was a staple in rental fleets and small contractor yards across Asia, Europe, and North America.
Hitachi Construction Machinery, founded in 1970 as a division of Hitachi Ltd., became one of the world’s leading excavator manufacturers by the early 2000s. The EX-series, including the EX60-2, contributed significantly to that growth, with tens of thousands of units sold globally.
Swing Function Failure and Hydraulic Pressure Drop
A common issue reported with aging EX60-2 units is the failure of the swing function, even after partial hydraulic pump rebuilds. In one case, the front half of the main pump was rebuilt, restoring most functions—but the swing remained inoperative. Initial pressure readings showed:

• 500 psi at the swing brake input
  
• Only 5 psi at the swing motor output when activated
  

This dramatic pressure drop suggests a blockage, bypass, or relief valve malfunction within the swing circuit.
Understanding the Swing Circuit and Brake System
The swing system on the EX60-2 includes a hydraulic swing motor, a swing brake, and a control valve that regulates flow and direction. The swing brake is spring-applied and hydraulically released—meaning it defaults to locked unless pressurized.
Key components:

• Swing motor: Converts hydraulic flow into rotational movement
  
• Swing brake: Holds upper structure in place when inactive
  
• Control valve: Directs flow to swing motor based on joystick input
  
• Relief valve: Protects swing motor from overpressure
  

If the swing brake receives pressure but the motor does not, the issue likely lies downstream of the brake—either in the control valve, relief valve, or motor itself.
Relief Valve Contamination and Cleaning Strategy
Relief valves are designed to open at preset pressures to prevent damage. However, contamination from degraded seals, metal shavings, or dirty fluid can cause them to stick open or closed. In the EX60-2, the swing relief valve is mounted on the main control valve block and can be accessed by removing the right-side panel.
Cleaning steps:

• Remove relief valve using appropriate socket
  
• Inspect for debris, scoring, or stuck poppet
  
• Flush with clean hydraulic fluid or solvent
  
• Replace O-rings and seals with OEM-grade parts
  
• Reinstall and torque to spec (typically 40–60 ft-lbs)
  

In one field case, a technician in British Columbia restored swing function by cleaning the relief valve and replacing a worn spring that had lost tension.
Pump Rebuild Limitations and Flow Testing
Rebuilding only the front half of the main pump may restore boom and travel functions but leave swing and auxiliary circuits underpowered. The EX60-2 uses a dual-section pump, with separate flow paths for different functions. If the rear section remains worn, swing flow may be insufficient.
Recommended diagnostic steps:

• Flow test at swing motor inlet using a hydraulic flow meter
  
• Compare readings to factory spec (typically 10–15 GPM at full throttle)
  
• Check pilot pressure at joystick valve (should be 300–500 psi)
  
• Inspect case drain line for excessive flow, indicating internal leakage
  

If flow is low and pressure is normal, the pump’s rear section may need rebuilding or replacement.
Historical Anecdote and Operator Insight
In 2011, a contractor in Osaka reported similar symptoms on an EX60-2 used for sidewalk demolition. After weeks of troubleshooting, he discovered a cracked internal seal in the swing control valve that allowed fluid to bypass directly to tank. The repair involved removing the valve block and replacing the internal spool seals—restoring full swing function and saving the machine from premature retirement.
Preventive Maintenance and Long-Term Reliability
To avoid swing failures and hydraulic degradation:

• Change hydraulic fluid every 1,000 hours or annually
  
• Use ISO 46 hydraulic oil with anti-wear additives
  
• Replace pilot filter and return filter every 500 hours
  
• Inspect relief valves and control spools during major service
  
• Flush system after pump rebuilds to remove debris
  

Recommended upgrades:

• Install in-line magnetic filter to trap metal particles
  
• Add pressure gauges to monitor swing circuit in real time
  
• Use infrared thermometer to check valve block temperatures under load
  

Conclusion
Swing failure in the Hitachi EX60-2 often stems from overlooked hydraulic components—especially relief valves and partially rebuilt pumps. With methodical diagnostics, including pressure and flow testing, most issues can be traced to contamination, bypass leakage, or incomplete pump restoration. The EX60-2 remains a capable machine, and with proper care, its swing system can be brought back to full performance—proving once again that even aging iron has plenty of life left when treated with respect and precision.