Removing the Counterweight on a Hitachi EX50URG Mini Excavator

[MikePhua]

The EX50URG and Its Compact Excavator Lineage
The Hitachi EX50URG is part of Hitachi’s compact excavator series developed in the late 1990s and early 2000s to meet growing demand for urban-friendly, high-performance machines. With an operating weight of approximately 5 metric tons and a dig depth exceeding 3.5 meters, the EX50URG was designed for tight job sites, utility trenching, and landscaping. Its zero-tail swing configuration allowed operators to work close to walls and obstacles without compromising stability.
Hitachi Construction Machinery, founded in 1970, became a global leader in hydraulic excavator design through its emphasis on precision, durability, and operator comfort. The EX series, including the EX50URG, was widely adopted in Asia and North America, with thousands of units sold before the ZX series replaced it.
Why Remove the Counterweight
The counterweight on the EX50URG serves a critical function—balancing the machine during digging and lifting. However, removal may be necessary for:

• Accessing rear hydraulic components or engine mounts
  
• Transporting the machine within tight clearance limits
  
• Performing structural repairs or repainting
  
• Replacing damaged counterweight due to impact
  

Unlike larger excavators, the EX50URG’s counterweight is compact but still heavy, typically weighing between 300 and 500 kilograms. Its removal requires careful planning to avoid damage to the frame or injury to personnel.
Preparation and Safety Measures
Before attempting removal:

• Park the machine on level ground and engage the parking brake
  
• Disconnect the battery to prevent accidental electrical activation
  
• Use lifting equipment rated for at least 1,000 kilograms
  
• Inspect the counterweight for lifting eyes or bolt-on brackets
  
• Clear the area of debris and ensure adequate lighting
  

Operators should wear steel-toe boots, gloves, and eye protection. A second person should assist with alignment and spotting during the lift.
Counterweight Mounting and Removal Procedure
The EX50URG counterweight is typically secured by:

• Four to six high-tensile bolts threaded into the rear frame
  
• Alignment pins or slots to prevent lateral movement
  
• A recessed cavity that nests into the frame for stability
  

To remove:

• Loosen all bolts incrementally to avoid stress on one side
  
• Support the counterweight with a hoist or forklift before final bolt removal
  
• Slide the counterweight rearward slowly, watching for interference with hoses or wiring
  
• Lower the unit onto a padded surface or pallet for inspection
  

Some models may include a wiring harness for rear lights or reflectors. Disconnect these carefully and label connectors for reinstallation.
Common Challenges and Solutions
Operators have reported several issues during removal:

• Rusted bolts requiring penetrating oil or heat
  
• Misaligned lifting due to uneven weight distribution
  
• Hidden wiring or hydraulic lines routed near the mounting points
  

Solutions include:

• Using impact tools with torque control to avoid bolt head stripping
  
• Installing temporary guide rods to maintain alignment during lift
  
• Consulting the service manual for torque specs and bolt patterns
  

One technician in British Columbia removed the counterweight to access a leaking hydraulic hose. He discovered that the hose had been pinched between the frame and counterweight during a previous repair. After rerouting the hose and reinstalling the weight with new bolts, the machine operated smoothly.
Reinstallation and Torque Specifications
When reinstalling:

• Clean all mating surfaces and apply anti-seize compound to bolts
  
• Use a torque wrench to tighten bolts to manufacturer specs (typically 180–220 Nm)
  
• Reconnect any wiring and test rear lights or sensors
  
• Verify that the counterweight sits flush and does not interfere with swing or travel
  

After installation, operate the machine briefly to confirm balance and stability. Monitor for unusual vibration or noise.
Recommendations for Long-Term Maintenance
To avoid future removal complications:

• Inspect counterweight bolts annually for corrosion or looseness
  
• Apply rust inhibitor to exposed metal surfaces
  
• Keep rear frame area clean to prevent debris buildup
  
• Document any modifications or repairs involving the counterweight
  

For machines operating in coastal or humid environments, consider applying marine-grade coatings to the counterweight and mounting hardware.
Conclusion
Removing the counterweight on a Hitachi EX50URG is a manageable task with the right tools and preparation. Whether for repair, transport, or inspection, understanding the mounting system and safety protocols ensures a smooth process. In compact excavators, every kilogram counts—and the counterweight is more than ballast. It’s a precision component that deserves respect and care.