Hitachi EX120-3: A Comprehensive Overview

[MikePhua]

The Hitachi EX120-3 is a 12-ton hydraulic crawler excavator that has earned a reputation for its reliability and versatility in various construction and excavation tasks. Manufactured during the late 1990s and early 2000s, this model has been a workhorse for many operators worldwide. In this article, we will delve into its specifications, common issues, maintenance practices, and real-world experiences to provide a comprehensive understanding of the EX120-3.

Technical Specifications
The EX120-3 is powered by a turbocharged Isuzu A-4BG1T engine, delivering approximately 81 horsepower (60 kW) at 2,100 rpm. This engine provides the necessary power for the machine's hydraulic system, which boasts a pump flow capacity of 50.2 gallons per minute (189 L/min) and a system relief valve pressure of 4,980 psi. The excavator's operating weight is around 11,800 kg (26,000 lbs), making it suitable for a wide range of tasks.
Key Specifications:

• Engine Model: Isuzu A-4BG1T
  
• Horsepower: 81 hp (60 kW) @ 2,100 rpm
  
• Hydraulic Pump Flow: 50.2 gpm (189 L/min)
  
• Relief Valve Pressure: 4,980 psi
  
• Operating Weight: 11,800 kg (26,000 lbs)
  
• Max Digging Depth: 18.28 ft (5.57 m)
  
• Max Reach Along Ground: 25.69 ft (7.83 m)
  
• Tail Swing Radius: 6.99 ft (2.13 m)
  
• Ground Clearance: 1.45 ft (0.44 m)
  

Common Issues and Troubleshooting
While the EX120-3 is known for its durability, like any heavy machinery, it is not without its issues. Operators have reported several recurring problems:

1. Hydraulic System Failures: Over time, components such as the pilot pump and pilot valve may become clogged with debris, leading to power loss and erratic machine behavior. Replacing these parts and ensuring the hydraulic system is clean can resolve such issues.
   
2. Hydraulic Overheating: Extended operation or heavy loads can cause the hydraulic system to overheat, resulting in power loss. Regular maintenance, including checking hydraulic oil levels and quality, is essential to prevent this.
   
3. Drive Motor Problems: Issues with the drive motor, such as internal damage or wear, can lead to one side of the machine losing power. Inspecting and replacing faulty drive motors can restore functionality.
   
4. Undercarriage Wear: The undercarriage components, including tracks and rollers, are subject to wear and tear. Regular inspection and timely replacement of worn parts can prolong the life of the machine.
   

Maintenance Practices
To ensure the longevity and optimal performance of the EX120-3, regular maintenance is crucial:

• Hydraulic System: Check hydraulic oil levels daily and replace filters as per the manufacturer's recommendations. Contaminated oil can lead to system failures.
  
• Engine: Regularly inspect the engine for oil leaks and ensure the cooling system is functioning correctly to prevent overheating.
  
• Undercarriage: Inspect tracks, rollers, and sprockets for wear. Replace worn components promptly to avoid further damage.
  
• Electrical System: Check all electrical connections and wiring for signs of wear or corrosion. Clean and tighten connections as needed.
  

Real-World Experiences
Operators have shared various experiences with the EX120-3:

• "I've had my EX120-3 for over 5 years. It's been a reliable machine, but I've had to replace the pilot pump twice due to debris clogging. Regular maintenance is key." – John D., Excavation Contractor
  
• "The undercarriage on my EX120-3 wore out quicker than expected. I operate in rocky terrain, so I had to replace the tracks and rollers after 3,000 hours." – Sarah M., Construction Foreman
  

These anecdotes highlight the importance of regular maintenance and the impact of operating conditions on the machine's longevity.

Conclusion
The Hitachi EX120-3 remains a solid choice for many in the construction and excavation industries. Its robust design and reliable performance make it a valuable asset. However, like all machinery, it requires regular maintenance and timely repairs to ensure it continues to operate efficiently. By staying proactive with maintenance and addressing issues promptly, operators can maximize the lifespan and productivity of their EX120-3 excavators.