Hitachi EX120 Excavator: Comprehensive Review, Challenges, and Practical Solutions

[MikePhua]

Overview of the Hitachi EX120 Excavator
The Hitachi EX120 is a versatile and powerful mid-sized excavator widely applied across construction, landscaping, and utility projects. It's designed for efficient digging, loading, and material handling with a focus on operator comfort, safety, and productivity. The excavator boasts an advanced hydraulic system offering smooth and precise control, backed by an engine delivering around 81 horsepower, with a turbocharged design providing high torque.
Key Specifications and Performance Metrics

• Engine Model and Power: The excavator is equipped with a turbocharged A-4BG1T engine producing approximately 81 hp (60 kW) at 2100 rpm and a max torque of 231.6 lbs/ft at 1600 rpm.
  
• Hydraulic System: Features a robust hydraulic pump flow capacity around 50.2 gallons per minute (189 L/min) with a system relief valve pressure of about 4980 psi. This enables precise, smooth hydraulic control ideal for varied excavation tasks.
  
• Dimensions and Weight:
  • Operating weight roughly 26,000 lbs (11,794 kg)
    
  • Ground clearance: 1.5 ft (0.46 m)
    
  • Track gauge approximately 6.6 ft (2 m)
    
  • Height to top of cab: close to 9 ft (2.7 m)
    
  • Width outside tracks: about 8.2 ft (2.5 m)
    
  • Max travel speed around 3.5 mph (5 kph)
    
• Digging Capabilities:
  • Maximum digging depth from 17 ft (5 m) to nearly 20 ft (6 m) depending on boom/stick configuration
    
  • Max cutting height ranges from 27.4 to 29.2 ft (8–9 m)
    
  • Maximum reach on the ground up to about 28.3 ft (8.6 m)
    
  • Bucket capacities span from around 0.3 to 0.9 cubic yards, allowing flexibility in material handling volume.
    

Common Challenges and Considerations

• Hydraulic Component Wear: Given its reliance on hydraulic power, hoses, valves, and seals require regular inspection and maintenance to prevent leaks or pressure loss that impede performance.
  
• Engine Durability and Cooling: Turbocharged engines generate significant heat; cooling systems (radiators, fans, coolant levels) must be maintained diligently to avoid overheating and engine damage.
  
• Undercarriage Wear: Tracks, rollers, and sprockets face constant abrasive terrain challenges; improper tension or worn parts can lead to decreased mobility and increased maintenance costs.
  
• Operator Comfort and Cab Ergonomics: While the EX120 cab is designed for comfort with ergonomic controls and good visibility, some operators have cited potential improvements in noise insulation and seat adjustability in harsh working environments.
  
• Electrical and Control System Reliability: Like modern excavators, the EX120 houses sensors and control electronics that can malfunction, requiring diagnostic capability and timely repairs to avoid operational interruptions.
  
• Attachment Versatility and Compatibility: Attachments like hydraulic breaker hammers, crusher buckets, rotary screening buckets, and grapples require proper hydraulic and mechanical integration to maximize productivity; users may experience issues if adapters or hoses are improperly matched.
  

Terminology Explained

• Hydraulic Pump Flow Capacity: The volume of hydraulic fluid the pump moves per minute, influencing the speed and power of hydraulic functions.
  
• Relief Valve Pressure: A safety feature to limit system pressure and prevent damage by releasing excess hydraulic pressure.
  
• Turbocharged Engine: An engine equipped with a turbine-driven forced induction device to improve power and efficiency.
  
• Bucket Capacity: The volume the bucket can hold, affecting material movement per cycle.
  
• Undercarriage Components: Includes tracks, rollers, sprockets, and idlers that support movement over terrain.
  
• Swing Speed: The rate (rpm) at which the upper structure rotates.
  

Maintenance Suggestions and Solutions

• Conduct regular hydraulic system inspections, including hose and seal checks and fluid replacement to prevent leaks and maintain pressure.
  
• Implement a thorough cooling system maintenance regime: monitor coolant levels, clean radiators, and test thermostats to prevent engine overheating.
  
• Perform undercarriage checks and adjustments: monitor track tension daily, lubricate rollers, and replace worn parts to extend system life and maintain mobility.
  
• Carry out engine oil and filter changes on schedule and inspect the air intake system to ensure optimal engine performance.
  
• Address electrical system issues promptly, including sensor recalibrations and wiring repairs, to reduce downtime.
  
• Opt for quality attaching accessories compatible with the EX120’s hydraulic system and specifications to maximize versatility and efficiency.
  
• Operator training on proper control use and maintenance routines is critical to reduce operational errors and machine wear.
  

Field Stories and Real-world Use Cases
A contractor utilizing the EX120 on mixed urban construction projects emphasized the importance of the machine’s ergonomic design, noting that the spacious cab and intuitive controls reduce operator fatigue during long shifts. However, attention was required to maintain the cooling system adequately, especially in summer months when overheating risk increased during continuous heavy digging.
Another user adapted the EX120 with a long-reach arm attachment for deep foundation excavation, significantly improving their ability to handle large-scale tasks without leasing additional heavy machinery. Proper hydraulic hose customization and routine inspections were essential to maintain safety and performance.
In a demolition case, utilizing the EX120 with a hydraulic breaker hammer attachment allowed efficient concrete chipping, which sped up project timelines. The operator shared that ensuring the correct breaker hammer size and compatible fitting prevented hydraulic overloads.
News from construction equipment expos highlighted the EX120 as a stable performer in the mid-sized excavator category but recommended ongoing software updates to the control system to enhance diagnostic accuracy and reliability.
Additional Practical Tips

• Keep a stock of critical spare parts, including filters, hoses, and hydraulic seals, to minimize downtime.
  
• Use high-quality lubricants and fluids tailored to the EX120’s specifications and the local climate to extend component life.
  
• Regularly update and calibrate machine software and control units to benefit from technological improvements.
  
• Consider installing additional monitoring sensors for hydraulic pressure and temperature to get early warnings of potential failures.
  
• Document all maintenance and repairs to create a helpful log for future troubleshooting and resale value enhancement.
  
• Follow safety protocols like wearing seat belts and using emergency stop switches integrated into the EX120 design.
  

By integrating thorough maintenance, operator education, and use of compatible attachments, the Hitachi EX120 remains a reliable, efficient, and valuable asset in a variety of construction environments. Its balance of power, reach, and operator comfort makes it well-suited for medium-scale earthmoving tasks, demolition, dredging, and material handling.
This excavator demonstrates how combining advanced hydraulics, practical ergonomics, and a wide range of attachments provides an adaptable solution capable of meeting diverse project needs effectively. Proper care and informed operation ensure long-term performance and return on investment.