Diagnosing Uneven Tracking on the Hitachi EX60 Excavator

[MikePhua]

The EX60 and Hitachi’s Compact Excavator Legacy
The Hitachi EX60 was introduced in the early 1990s as part of Hitachi’s compact excavator lineup, designed for urban construction, utility trenching, and light demolition. With an operating weight around 6 metric tons and powered by a 4-cylinder Isuzu diesel engine, the EX60 offered a balance of power, maneuverability, and hydraulic precision. Its undercarriage featured a dual-track drive system with independent final drives, allowing for zero-radius turns and fine control in tight spaces.
Hitachi’s excavator lineage is rooted in its partnership with John Deere and its reputation for hydraulic refinement. The EX60 became a staple in rental fleets and contractor yards across Asia, Europe, and North America, praised for its reliability and ease of service.
Terminology Annotation

• Tracking: The movement of the excavator on its tracks, either forward, reverse, or turning.
  
• Final Drive: A planetary gear reduction system that transmits hydraulic motor torque to the track sprocket.
  
• Travel Motor: A hydraulic motor that powers the track drive, mounted to the final drive.
  
• Swing Motor: A separate hydraulic motor that rotates the upper structure of the excavator.
  

Symptoms of Uneven or Weak Tracking
Operators have reported issues where the EX60 tracks unevenly—one side moves slower or fails to respond under load. Common symptoms include:

• Right or left track sluggish or non-responsive
  
• Machine veers during straight travel
  
• Audible difference in motor pitch between sides
  
• No visible hydraulic leaks or fault codes
  

In one trenching job in Malaysia, an EX60 consistently pulled to the right during travel. The operator compensated by feathering the left joystick, but the imbalance worsened over time. After inspection, the left travel motor was found to have internal bypass leakage, reducing torque output.
Root Causes and Diagnostic Strategy
Uneven tracking can stem from hydraulic, mechanical, or control-related faults. Common causes include:
Hydraulic faults:

• Internal leakage in travel motor or final drive
  
• Contaminated hydraulic fluid causing spool valve sticking
  
• Pressure imbalance between left and right travel circuits
  

Mechanical faults:

• Worn sprocket or track tensioner
  
• Debris lodged in track rollers or idlers
  
• Final drive gear wear or bearing failure
  

Control faults:

• Joystick valve wear causing uneven signal
  
• Pilot pressure drop due to clogged filters
  
• Electrical solenoid malfunction in proportional valve (if equipped)
  

Diagnostic steps:

• Measure pilot pressure at both travel valves (typical range: 400–600 psi)
  
• Check main pump output pressure under load (target: ~4,500 psi)
  
• Inspect travel motor case drain flow for excessive bypass
  
• Compare track speed using stopwatch over fixed distance
  
• Remove track guards and inspect sprocket and roller condition
  

In a fleet in Queensland, replacing a worn travel motor seal and flushing the hydraulic system restored balanced tracking on three EX60 units. The original fluid showed signs of water contamination and metal particulate.
Component Notes and Suggested Repairs
Key components to inspect or replace:

• Travel motor: Hitachi part #4438612 or equivalent
  
• Final drive assembly: Planetary gear set with integrated brake
  
• Track tensioner: Grease-filled cylinder with recoil spring
  
• Hydraulic filter: 10-micron spin-on type, changed every 500 hours
  

Recommended specs:

• Hydraulic fluid: ISO VG 46 or Hitachi Super EX46
  
• Track tension sag: ~25–35 mm between bottom rollers
  
• Travel motor case drain flow: <1 liter/min under load
  
• Sprocket wear limit: <2 mm tooth tip rounding
  

Tips for repair:

• Always replace both travel motors if imbalance persists after one side is repaired
  
• Use magnetic plug in final drive to monitor gear wear
  
• Flush hydraulic lines with clean fluid before installing new motor
  
• Torque travel motor bolts to spec (~180 Nm) and use thread locker
  

In a restoration project in Poland, a contractor added pressure gauges to both travel circuits for real-time monitoring. This helped identify early signs of imbalance and prevented costly downtime.
Preventive Measures and Long-Term Reliability
To maintain smooth tracking:

• Inspect track tension weekly and adjust as needed
  
• Replace hydraulic filters every 500 hours or sooner in dusty environments
  
• Monitor fluid temperature and avoid prolonged travel under high load
  
• Grease track rollers and idlers monthly
  
• Train operators to avoid sharp turns at full speed, which stresses final drives
  

Suggested inspection checklist:

• Equal track speed in forward and reverse
  
• No abnormal noise from final drives
  
• Clean fluid in sight glass with no foam or discoloration
  
• Joystick response smooth and proportional
  

In a utility fleet in Arizona, implementing a travel performance log reduced tracking complaints and improved maintenance scheduling.
Final Thoughts
Uneven tracking on the Hitachi EX60 is often a symptom of deeper hydraulic or mechanical imbalance. While the machine’s compact design makes it ideal for tight workspaces, its dual-drive system demands equal performance from both sides. With structured diagnostics, quality repairs, and preventive care, the EX60 can continue gliding across job sites with precision and power.
In the steady crawl of steel and the pulse of hydraulic flow, tracking is not just movement—it’s balance, control, and the quiet assurance that the machine is working as one.