Troubleshooting Slow Bucket Cylinder Movement on the Hitachi EX60-5

[MikePhua]

The Hitachi EX60-5 and Its Hydraulic Architecture
The Hitachi EX60-5 is a compact hydraulic excavator introduced in the mid-1990s as part of Hitachi Construction Machinery’s fifth-generation lineup. Designed for urban excavation, utility trenching, and light demolition, the EX60-5 features a well-balanced chassis, responsive pilot controls, and a robust hydraulic system. Powered by the Isuzu 4JB1T turbocharged diesel engine, it delivers approximately 60 horsepower and operates with dual hydraulic pumps capable of producing up to 3,900 psi.
Hitachi, founded in 1910 and headquartered in Tokyo, has long been a leader in hydraulic excavator innovation. The EX60 series sold extensively across Asia, Europe, and North America, with thousands of units still in service today. Its reliability and mechanical simplicity make it a favorite among independent contractors and fleet managers alike.
Terminology Annotation

• Bucket Ram: Also known as the bucket cylinder, this hydraulic actuator controls the curling and uncurling of the bucket.
  
• Pilot Pressure: Low-pressure hydraulic signal used to actuate main control valves; typically ranges from 400 to 600 psi.
  
• Spool Valve: A sliding valve element inside the control block that directs hydraulic flow to specific actuators.
  
• Shock Valve: A pressure relief valve designed to protect hydraulic components from sudden spikes or backpressure.
  

Symptoms of Slow Bucket Movement
Operators have reported that the bucket cylinder on the EX60-5 moves noticeably slower than the boom or dipper cylinders, particularly when curling inward. This sluggish behavior persists even at full engine RPM and with clean hydraulic filters. The issue appears isolated to the bucket function and is most pronounced during the roll-in phase.
Measured performance indicates a roll-in time of approximately 4.5 seconds at full throttle, compared to the expected 4.0 seconds. Roll-out speed remains within normal parameters at around 2.5 seconds. This discrepancy suggests a directional flow imbalance or pressure loss specific to the bucket circuit.
Diagnostic Strategy and Field Observations
To identify the root cause of slow bucket movement:

• Confirm engine speed reaches the rated 2,200 RPM under load
  
• Measure pilot pressure at the bucket control valve during both directions of movement
  
• Inspect spool valve travel and responsiveness for signs of sticking or partial engagement
  
• Test hydraulic pressure at the bucket cylinder ports using a calibrated gauge
  
• Check for internal leakage or bypass within the bucket cylinder itself
  

In one documented case, a technician discovered that the pilot pressure was marginally low due to a worn pilot pump. Replacing the pump restored full bucket speed without affecting other circuits.
Another common culprit is a partially blocked or malfunctioning shock valve. If the valve fails to open properly, it can restrict flow during high-demand movements like bucket curling, especially under load.
A Story from the Field
In County Cork, Ireland, a contractor operating an EX60-5 noticed the bucket was slow to respond during trenching. After verifying fluid levels and replacing filters, the issue persisted. A local hydraulic specialist suggested measuring pilot pressure and inspecting the spool valve. It was found that the spool was slightly misaligned due to wear in the control lever linkage. After realigning the linkage and flushing the pilot lines, the bucket returned to normal speed. The operator later installed a pressure gauge permanently on the pilot circuit to monitor performance during seasonal temperature changes.
Recommendations for Repair and Optimization
To improve bucket cylinder speed:

• Ensure engine RPM is calibrated and governor linkage is responsive
  
• Replace pilot filters and inspect pilot pump output
  
• Clean and lubricate spool valve linkages and detents
  
• Test and, if necessary, replace the shock valve associated with the bucket circuit
  
• Inspect bucket cylinder seals for internal leakage and rebuild if needed
  

For long-term reliability:

• Flush hydraulic system annually and replace fluid with OEM-grade oil
  
• Install quick-connect pressure test ports on key circuits
  
• Monitor cylinder stroke times monthly and log deviations
  
• Train operators to recognize early signs of hydraulic imbalance
  

Industry Trends and Legacy Support
As of 2025, Hitachi continues to support legacy models like the EX60-5 through its global dealer network. Aftermarket suppliers offer rebuilt cylinders, pilot pumps, and control valves compatible with the EX60 series. Some owners have retrofitted digital pressure sensors and flow meters to monitor hydraulic performance in real time.
With the rise of telematics and smart diagnostics, newer excavators offer automated alerts for hydraulic inefficiencies. While the EX60-5 lacks these features, its mechanical transparency allows skilled technicians to diagnose and resolve issues with minimal electronic intervention.
Conclusion
Slow bucket cylinder movement on the Hitachi EX60-5 is often caused by marginal pilot pressure, spool valve misalignment, or shock valve restriction. By methodically testing pressure, inspecting control components, and maintaining hydraulic cleanliness, operators can restore full performance and extend the life of this dependable machine. The EX60-5 remains a testament to Hitachi’s engineering legacy—simple, durable, and responsive when properly maintained.