EX60URG Counterweight Removal Thread Size

[MikePhua]

The Hitachi EX60URG and Its Engineering Legacy
The Hitachi EX60URG is a compact hydraulic excavator designed for urban construction, utility work, and confined-space operations. Developed in the late 1990s as part of Hitachi Construction Machinery’s global push into mid-size excavator markets, the EX60URG was tailored for regions with strict emissions and noise regulations. Hitachi, founded in 1910 and entering the construction equipment sector in 1965, became known for its precision hydraulic systems and durable undercarriage designs.
The EX60URG belongs to the EX series, which saw widespread adoption across Asia, Europe, and North America. Though exact sales figures for the EX60URG are not publicly disclosed, the EX60 series overall exceeded 50,000 units globally by the early 2000s. Its popularity stemmed from its balance of power, maneuverability, and serviceability—qualities that made it a staple in rental fleets and municipal projects.
Understanding the Counterweight Assembly
The counterweight on the EX60URG is a critical component designed to stabilize the machine during digging and lifting operations. It offsets the weight of the boom and arm when extended, preventing tipping and improving hydraulic efficiency. The counterweight is typically mounted at the rear of the upper structure and secured using threaded holes designed to accept lifting eye bolts.
Key terminology includes:

• Counterweight: A dense metal block, usually cast iron or steel, mounted to the rear of the excavator to balance the forward load.
  
• Eye Bolts: Heavy-duty threaded bolts with a looped head used for lifting or securing components.
  
• Thread Size: The diameter and pitch of the internal threads in the counterweight, which must match the eye bolts for safe removal.
  

In the case of the EX60URG, standard M24 bolts were found to be too small for the counterweight’s threaded holes, indicating a larger thread size—likely M30 or M36 depending on the production batch and regional variant.
Field Challenges and Practical Solutions
Removing the counterweight is often necessary for transport, major repairs, or repainting. However, mismatched thread sizes can delay operations and pose safety risks. One technician in the UK discovered that M24 bolts would not engage, prompting a search for the correct specification. This scenario is common in older machines where documentation may be missing or inconsistent.
Recommended steps for safe counterweight removal include:

• Thread Verification: Use a thread gauge or caliper to measure the diameter and pitch of the hole. If unavailable, test-fit bolts incrementally starting from M24 upward.
  
• Bolt Grade: Use high-tensile bolts rated at least Grade 8.8 to ensure lifting integrity.
  
• Torque Settings: When installing eye bolts, torque them to manufacturer specifications—typically between 250–300 Nm for M30 bolts.
  
• Load Testing: Before lifting, apply a small load to verify bolt engagement and structural integrity.
  

In one case, a contractor in Singapore used a hydraulic crane to lift the counterweight but failed to verify bolt engagement. The result was a dropped load that damaged the undercarriage and led to a costly insurance claim. This incident underscores the importance of proper thread matching and pre-lift inspection.
Counterweight Design Evolution and Regional Variants
Hitachi’s counterweight designs have evolved over time. Early EX series models used cast iron blocks with fixed mounting points, while later versions incorporated modular designs with removable panels for easier servicing. In Japan, some EX60URG units were fitted with lighter counterweights to comply with road transport weight limits, using M30 threads instead of M36.
In colder climates, counterweights were sometimes filled with sand or concrete to reduce rusting and improve cold-weather stability. These regional adaptations complicate maintenance and require technicians to verify specifications before attempting removal.
Recommendations for Technicians and Fleet Managers
To streamline counterweight servicing and avoid delays, consider the following practices:

• Maintain a Bolt Kit: Stock a range of eye bolts from M24 to M36 with matching nuts and washers.
  
• Document Thread Sizes: Record thread specifications during initial inspection and attach labels to the counterweight for future reference.
  
• Use Thread Lubricant: Apply anti-seize compound to bolts before installation to prevent galling and ease future removal.
  
• Train Operators: Educate field personnel on safe lifting procedures and the importance of thread matching.
  

For fleet managers overseeing multiple EX60URG units, standardizing counterweight removal procedures can reduce downtime and improve safety. Consider creating a checklist that includes thread verification, bolt inspection, and lift testing.
Conclusion
The EX60URG remains a reliable and versatile excavator, but its counterweight removal process demands attention to detail—especially regarding thread size. Whether in a motocross track in the UK or a utility trench in Tokyo, technicians must approach the task with precision and caution. By understanding the machine’s design history, verifying specifications, and applying best practices, operators can ensure safe and efficient maintenance of this enduring Hitachi workhorse.