Choosing the Right Track Chains for a Kobelco SK120 LC Excavator

[MikePhua]

The Kobelco SK120 LC and Its Undercarriage Configuration
The Kobelco SK120 LC is a mid-size hydraulic excavator designed for general construction, trenching, and utility work. First introduced in the late 1990s, the SK120 series helped establish Kobelco’s reputation for smooth hydraulic control and durable undercarriage systems. Kobelco, founded in Japan in 1930, became a global player in the excavator market by the early 2000s, with the SK120 LC selling widely across North America, Europe, and Asia.
The “LC” designation refers to the long carriage variant, which features an extended track frame for improved stability and lifting capacity. This configuration requires longer track chains—typically 46 links per side—compared to the short carriage version, which uses 43 links. The difference in link count directly affects ground contact length, weight distribution, and undercarriage wear patterns.
Understanding Track Chain Specifications
Track chains are composed of interconnected links that form the continuous loop around the sprockets, rollers, and idlers. Each link includes a bushing, pin, and shoe mounting surface. The total number of links must match the frame length and sprocket pitch to ensure proper tension and alignment.
Terminology:

• Link count: The number of chain segments forming the track loop
  
• Pitch: The center-to-center distance between adjacent pins
  
• Bushing: A cylindrical sleeve that rotates around the pin, absorbing wear
  
• Master link: A removable segment used to open or close the chain loop
  

For the SK120 LC, a 46-link chain with a pitch of 171 mm is standard. Deviating from this specification can cause misalignment, excessive wear, or derailment.
OEM vs. Aftermarket Track Chains
Operators often face the choice between OEM (Original Equipment Manufacturer) chains and aftermarket alternatives. While OEM parts offer guaranteed compatibility, aftermarket suppliers such as ITR, Trek, and ValuPart provide cost-effective options with varying degrees of quality.
Comparison factors:

• Material hardness (typically 50–55 HRC for bushings)
  
• Heat treatment consistency
  
• Pin-to-bushing interference fit
  
• Warranty coverage (usually 12–24 months)
  
• Availability of sealed vs. greased chains
  

In one Pennsylvania-based repair shop, a contractor replaced worn chains with aftermarket 46-link assemblies from Trek. After 1,200 hours of operation, the chains showed minimal elongation and no pin walk—validating the supplier’s quality claims.
Chain Sourcing and Regional Suppliers
Finding the right supplier depends on location, urgency, and budget. In Canada, Toronto Tracparts Ltd. is known for stocking undercarriage components for Kobelco machines, including track chains, rollers, and sprockets. In the U.S., distributors in California and the Midwest often carry inventory for SK-series excavators.
Tips for sourcing:

• Confirm serial number and undercarriage variant before ordering
  
• Request dimensional drawings or sample links for verification
  
• Ask about shipping lead times and return policies
  
• Consider bundling chains with rollers and sprockets for full rebuilds
  

Some suppliers offer pre-assembled track groups with shoes mounted, reducing installation time and labor costs.
Installation and Tensioning Best Practices
Installing new track chains requires precision and safety awareness. Improper tensioning can lead to premature wear or derailment. The SK120 LC uses a grease-filled tensioner with a recoil spring to maintain proper slack.
Installation steps:

• Remove old chains using a master pin press or torch
  
• Clean sprockets and rollers thoroughly
  
• Align new chains and install master link with retaining hardware
  
• Pump grease into the tensioner until 10–20 mm of sag remains at midpoint
  
• Cycle the machine forward and backward to seat the chain
  

In one field anecdote, a technician over-tightened the chain, causing the recoil spring to bind and crack. Replacing the spring added downtime and cost—highlighting the importance of following manufacturer specs.
Conclusion
Selecting and installing track chains for a Kobelco SK120 LC excavator requires attention to link count, pitch, supplier quality, and tensioning technique. Whether choosing OEM or aftermarket components, matching the chain to the long carriage frame is essential for performance and longevity. With proper sourcing and installation, the SK120 LC can continue operating smoothly across varied terrain—proving that even the smallest link plays a critical role in keeping heavy iron moving.