Troubleshooting the Hammer Circuit on Hitachi EX130 Excavators

[MikePhua]

The hydraulic hammer attachment is a vital tool for demolition and construction projects involving Hitachi EX130 excavators. Understanding the hammer circuit and troubleshooting its common problems ensures smooth operation and minimizes downtime. This article delves into the hammer circuit specifics of the Hitachi EX130, typical issues, troubleshooting methods, and helpful insights for operators and technicians.
Understanding the Hammer Circuit
The hammer circuit on a Hitachi EX130 is designed to supply hydraulic power from the excavator’s main hydraulic system to the hydraulic breaker (hammer) attachment. It generally includes:

• Control Valve: Manages the flow of hydraulic oil to the hammer.
  
• Pressure Relief Valve: Protects the system from excessive pressure.
  
• Solenoid Valve: Electrically controls the opening and closing of hydraulic flow.
  
• Hydraulic Lines: Connect the excavator’s hydraulic system to the hammer.
  
• Electric Switch or Lever: Operated by the driver to engage or disengage the hammer.
  

The hammer circuit must maintain proper pressure and flow to allow the hammer to operate efficiently. The system uses an electrical control signal from the cab to activate the solenoid valve, which then allows hydraulic oil to flow to the hammer.
Common Symptoms of Hammer Circuit Issues

• Hammer does not activate despite the hydraulic system running.
  
• Intermittent hammer operation — hammer stops and starts unexpectedly.
  
• Reduced hammer impact force or inconsistent pounding.
  
• Unusual noises or vibrations during hammer operation.
  
• Hydraulic oil leaks or visible damage to hoses.
  

Common Causes of Hammer Circuit Failures

• Electrical faults such as blown fuses, faulty solenoid valves, or wiring issues.
  
• Hydraulic blockages or leaks in hoses or valves.
  
• Faulty control valves that fail to direct flow properly.
  
• Pressure relief valve malfunctions causing improper system pressure.
  
• Operator errors such as incorrect switch operation or mechanical linkage problems.
  

Step-by-Step Troubleshooting Process

1. Visual Inspection
   • Check hydraulic hoses and fittings for leaks, cracks, or kinks.
     
   • Inspect electrical wiring and connectors related to the hammer circuit for damage or corrosion.
     
   • Verify the hammer attachment is securely mounted and mechanically sound.
     
2. Electrical Checks
   • Test the hammer switch or lever in the cab to ensure it sends a signal.
     
   • Measure voltage at the solenoid valve terminals to confirm it receives power.
     
   • Check fuses and relays protecting the hammer circuit.
     
   • Use a multimeter to check solenoid coil resistance for open or short circuits.
     
3. Hydraulic Pressure Testing
   • Connect pressure gauges to the hammer circuit test points.
     
   • Compare measured pressures against the manufacturer’s specifications.
     
   • Inspect for pressure drops when the hammer is supposed to be active.
     
   • Verify the pressure relief valve setting and operation.
     
4. Control Valve Examination
   • Remove and inspect control valves for internal wear, dirt, or sticking components.
     
   • Clean or replace valves as needed.
     
   • Check spool movement and spring conditions.
     
5. Solenoid Valve Testing
   • Manually actuate the solenoid valve to check hydraulic flow.
     
   • Replace faulty solenoid valves if they fail to respond electrically or hydraulically.
     
6. Final System Test
   • After repairs, test the hammer operation under load.
     
   • Observe for consistent hammer performance without leaks or electrical faults.
     

Technical Terms Explained

• Solenoid Valve: An electromechanically operated valve used to control hydraulic flow based on electrical input.
  
• Pressure Relief Valve: A safety valve designed to open at a set pressure to prevent system overpressure.
  
• Hydraulic Flow: Movement of hydraulic fluid within the system to power attachments.
  
• Control Valve Spool: The sliding component inside a valve that directs fluid flow.
  
• Multimeter: An instrument used to measure electrical voltage, current, and resistance.
  

Additional Insights and Stories
One operator recounted a case where the hammer on his Hitachi EX130 suddenly stopped working. After following the troubleshooting steps, he found a corroded solenoid connector hidden behind the console panel. Cleaning and securing the connection restored power, highlighting the importance of checking seemingly minor electrical issues.
Another example involved a construction crew working on urban demolition who experienced inconsistent hammer strikes. The root cause was a partially clogged hydraulic filter, which caused pressure fluctuations. Replacing the filter prevented further interruptions and saved the project timeline.
The hammer circuit design on the Hitachi EX130 reflects decades of hydraulic engineering advancements. Hydraulic breakers first emerged in the mid-20th century and have continuously evolved to improve durability, impact force, and energy efficiency. Today’s systems combine robust hydraulic components with smart electrical controls to deliver precise hammer operation.
Maintenance Tips to Prevent Hammer Circuit Problems

• Regularly inspect and replace hydraulic filters to maintain clean fluid flow.
  
• Keep electrical connectors clean and dry to avoid corrosion.
  
• Use genuine replacement parts for valves and solenoids.
  
• Periodically check hydraulic hose condition and replace aging hoses.
  
• Follow manufacturer-recommended service intervals for the hammer attachment and excavator hydraulic system.
  

Understanding the hammer circuit in Hitachi EX130 excavators empowers operators and technicians to diagnose and solve issues efficiently, minimizing downtime and costly repairs. With attention to detail and a systematic approach, hammer performance can remain reliable even in the most demanding job sites.