Komatsu PC120-6: Overview and Maintenance Insights

[MikePhua]

The Komatsu PC120-6 is a popular model of hydraulic excavator that has been widely used in construction, mining, and heavy-duty industrial applications. Known for its reliability, power, and efficiency, the PC120-6 offers operators excellent digging capabilities, maneuverability, and operational comfort. However, like any complex piece of machinery, regular maintenance, troubleshooting, and understanding its operational quirks are key to ensuring its longevity and performance. This article explores the key features of the PC120-6, its development, common maintenance issues, and best practices for keeping it in optimal condition.
Introduction to the Komatsu PC120-6
The Komatsu PC120-6, part of Komatsu’s mid-sized hydraulic excavator series, was designed with operators' needs in mind. It provides a balance of power, agility, and versatility, making it ideal for a wide range of jobs, from digging and trenching to lifting and material handling. While newer models have since been released, the PC120-6 remains a reliable and sought-after machine due to its performance and the widespread availability of parts.
Key Specifications of the Komatsu PC120-6:

• Operating Weight: Around 12,000 kg (26,455 lbs)
  
• Engine Power: Approximately 75 kW (101 hp)
  
• Bucket Capacity: 0.5 to 0.7 cubic meters
  
• Maximum Digging Depth: 5.8 meters (19 feet)
  
• Maximum Reach: 8.2 meters (26.9 feet)
  
• Operating Pressure: 34.3 MPa (4,980 psi)
  

This combination of specifications makes the PC120-6 ideal for medium to heavy-duty tasks, with the flexibility to perform a variety of functions depending on the attachments and job requirements.
Development of the Komatsu PC120-6
Introduced in the early 1990s, the Komatsu PC120-6 was designed to offer superior lifting and digging performance while maintaining a manageable size for projects that required both power and agility. Komatsu, a global leader in heavy equipment manufacturing, aimed to design a machine that could handle construction tasks while being easy to transport and operate in tight spaces.
The PC120-6 was a significant step forward in terms of hydraulics, operator comfort, and overall efficiency. It was equipped with a fuel-efficient engine and featured advanced hydraulics, which made it more responsive and precise than its predecessors. In addition to its versatility, it was designed for ease of maintenance, with features like easily accessible components and a durable undercarriage that contributed to its longevity.
Common Maintenance Issues with the Komatsu PC120-6
While the Komatsu PC120-6 is generally a reliable machine, like all heavy equipment, it can experience wear and tear over time. Below are some of the most common issues that operators and maintenance teams face, along with possible solutions.

1. Hydraulic System Problems
   The hydraulic system is a key component in the PC120-6, providing power to the boom, arm, bucket, and swing functions. However, issues like reduced power, slow movement, or unusual noises can arise due to several factors.
   Common Issues:
   • Low Hydraulic Fluid: Low levels of hydraulic fluid can lead to poor hydraulic performance. This is often accompanied by noise, sluggish movements, and erratic behavior.
     
   • Clogged Filters: Over time, filters can become clogged with debris, reducing the flow of hydraulic fluid and impairing the performance of the machine.
     
   Solutions:
   • Regularly check and maintain fluid levels, topping up with the correct type of hydraulic oil.
     
   • Change hydraulic filters according to the maintenance schedule, ensuring the system is clean and free of contaminants.
     
2. Engine Performance Problems
   Engine-related issues, such as reduced power, excessive smoke, or hard starting, are common in older machines like the PC120-6. These can be caused by clogged air filters, fuel system problems, or worn-out components.
   Common Issues:
   • Dirty Air Filters: Air filters can get clogged, reducing engine efficiency and power.
     
   • Fuel System Problems: Clogged fuel injectors or a dirty fuel filter can cause poor fuel combustion and engine performance.
     
   • Compression Loss: Over time, the engine’s compression can degrade, reducing power output.
     
   Solutions:
   • Regularly clean or replace air filters.
     
   • Check the fuel system, and clean or replace the fuel filter as needed.
     
   • Perform regular engine checks and compression tests to ensure the engine is operating optimally.
     
3. Undercarriage Wear
   The undercarriage, including the tracks, rollers, and sprockets, is subject to significant wear due to constant ground contact. Inadequate lubrication or misalignment can accelerate wear and lead to costly repairs.
   Common Issues:
   • Track Wear: Tracks are often the first to show signs of wear, especially if the machine operates on rough or abrasive terrain.
     
   • Worn Rollers and Sprockets: Rollers and sprockets can wear down, causing misalignment or even track slippage.
     
   Solutions:
   • Inspect the undercarriage regularly for signs of wear, including cracks in the track, worn sprockets, and damaged rollers.
     
   • Keep the undercarriage properly lubricated and replace worn components promptly to prevent further damage.
     
4. Electrical System Failures
   Electrical failures, though less common, can affect the functionality of the PC120-6, particularly with the machine's control system, lights, and starting system.
   Common Issues:
   • Dead Battery: A flat or dead battery can cause starting issues, and in extreme cases, may damage the electrical system if left unchecked.
     
   • Wiring Issues: Damaged wiring or loose connections can interrupt signals from sensors or cause malfunctions in the electrical system.
     
   Solutions:
   • Check the battery regularly and ensure that it is fully charged and in good condition.
     
   • Inspect all wiring and electrical connections for wear and tear, and replace any damaged parts as necessary.
     

Best Practices for Maintaining the Komatsu PC120-6
Regular maintenance and proper care are key to ensuring the Komatsu PC120-6 remains in peak working condition throughout its lifespan. Here are some best practices to follow:

1. Follow a Regular Maintenance Schedule
   Ensure that all routine maintenance, such as oil changes, filter replacements, and fluid checks, is performed according to the manufacturer’s recommended schedule. Keeping up with maintenance will prevent most issues and ensure the machine operates smoothly.
   
2. Inspect Daily Before Operation
   Before starting the machine each day, perform a visual inspection. Check for any visible leaks, wear on the tracks, or potential issues with the hydraulics or engine. Catching small problems early can prevent major breakdowns later.
   
3. Monitor Operating Conditions
   Be mindful of the operating environment. For example, operating on loose soil or rough terrain can put additional strain on the undercarriage. Similarly, excessive heat can impact the engine and hydraulic performance. Use the machine within its specified operating parameters to prolong its lifespan.
   
4. Use Genuine Komatsu Parts
   When replacing parts, always opt for genuine Komatsu parts. While aftermarket parts may be cheaper, they may not provide the same level of performance or durability as OEM parts.
   

Conclusion
The Komatsu PC120-6 remains one of the most reliable and versatile excavators in its class, offering a combination of power, efficiency, and ease of maintenance. However, as with any piece of heavy machinery, proper care, regular maintenance, and timely troubleshooting are essential to keep the machine operating at its best. By following a comprehensive maintenance plan and addressing common issues as they arise, operators can ensure the PC120-6 remains a dependable asset for many years to come.