Hitachi EX 120 Manual: A Comprehensive Guide for Operators and Technicians

[MikePhua]

Introduction
The Hitachi EX 120 is a popular mid-size hydraulic excavator known for its versatility, durability, and efficient performance in various industries, including construction, mining, and demolition. Proper maintenance and operation of this machine require a thorough understanding of its manual and technical specifications. This guide summarizes key insights from the EX 120 manual to assist operators and technicians in getting the most out of the machine.
Machine Overview
The Hitachi EX 120 is equipped with a powerful engine, advanced hydraulic systems, and a robust undercarriage. The machine is designed for tough environments, providing a solid balance of lifting power, digging depth, and working capacity. Whether you're excavating, lifting, or loading, the EX 120 is built for efficiency and reliability.
Engine Specifications
The EX 120 is powered by a diesel engine, known for its high output and fuel efficiency. Key engine features include:

• Engine Type: 4-cycle, direct injection diesel engine
  
• Horsepower: Typically around 85 to 100 hp (depending on the model year and configuration)
  
• Fuel Capacity: Approximately 200 liters
  
• Cooling System: Forced water circulation system with radiator and fan
  

Hydraulic System
The hydraulic system of the Hitachi EX 120 is crucial for effective operation and control. The hydraulic system includes:

• Main Pump: Variable displacement piston pump for efficient power delivery
  
• Boom, Arm, and Bucket Cylinders: Designed to provide smooth and powerful movement for digging, lifting, and loading tasks
  
• Hydraulic Tank Capacity: Typically between 120 to 160 liters, depending on the model
  
• Hydraulic Filtration System: Designed to maintain the cleanliness of the hydraulic fluid, ensuring long-term system performance
  

Undercarriage and Tracks
The undercarriage of the EX 120 is designed to handle heavy loads and provide excellent stability during operation. Features include:

• Track Length on Ground: Provides a stable footprint for better balance
  
• Track Width: Typically around 600 mm (depending on configuration)
  
• Track Tensioning System: Automatic or manual tensioning to maintain proper track alignment and prevent wear
  

Cab and Operator Comfort
The cabin of the Hitachi EX 120 is designed for operator comfort and ease of use. It features:

• Ergonomically Designed Seats: To reduce operator fatigue during long working hours
  
• Air Conditioning and Heating System: To ensure a comfortable working environment in various weather conditions
  
• Joystick Controls: For easy manipulation of boom, arm, and bucket movements
  
• Enhanced Visibility: Large windows and well-positioned mirrors for improved safety and operational efficiency
  

Maintenance and Service
Proper maintenance is critical to prolonging the life of your Hitachi EX 120 and ensuring it runs at peak efficiency. Key maintenance tasks include:

• Engine Oil and Filter Replacement: Regular oil changes as per the manufacturer's recommended intervals
  
• Hydraulic Fluid Checks: Ensure the hydraulic fluid levels are adequate and replace filters as needed
  
• Track Inspection: Periodically check the tracks for wear and ensure the tension is correct
  
• Greasing: Regular greasing of moving parts, such as the boom and arm, to reduce friction and wear
  
• Cooling System Maintenance: Regularly inspect the radiator, cooling fan, and hoses for any damage or blockages
  

Troubleshooting and Common Issues
Even with proper maintenance, issues may arise during operation. Some common problems and their solutions include:

• Engine Failure to Start: Check the battery charge, fuel supply, and glow plugs. Inspect the starter motor and connections for any faults.
  
• Hydraulic Power Loss: This could be due to low hydraulic fluid levels, air in the hydraulic system, or a malfunctioning pump.
  
• Uneven Track Wear: Inspect for misalignment or damage in the undercarriage components. Adjust the track tension as necessary.
  

Conclusion
The Hitachi EX 120 is a reliable and powerful excavator that, when properly maintained, can provide years of efficient service. Understanding its key components and how to properly maintain them ensures that the machine continues to perform optimally. Always consult the EX 120 manual for specific guidelines on maintenance, troubleshooting, and part specifications. Regular upkeep and timely repairs will help extend the service life of the equipment, allowing it to operate effectively in demanding conditions.