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Can a Komatsu Dash-8 Undercarriage Fit a Dash-7 Excavator
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Komatsu’s Dash Series Evolution
Komatsu Ltd., founded in 1921 in Japan, has grown into one of the world’s leading manufacturers of construction and mining equipment. Its hydraulic excavator line has long been a benchmark for durability and innovation. The Dash-7 and Dash-8 series represent two successive generations of mid-sized excavators, including popular models like the PC200-7 and PC220-8. These machines are widely used in infrastructure, quarrying, and forestry applications across Asia, Europe, and North America.
The Dash-7 series, introduced in the early 2000s, emphasized mechanical simplicity and robust steelwork. The Dash-8 series, released around 2006, brought refinements in fuel efficiency, electronic control, and operator comfort. By 2015, Komatsu had sold over 100,000 units across both series globally.
Undercarriage Compatibility Between Generations
A common question among fleet managers and rebuilders is whether the undercarriage from a Dash-8 excavator can be directly installed on a Dash-7 machine. Specifically, whether a PC200-8’s undercarriage can be fitted onto a PC220-7. While the two models share similar architecture, there are critical differences in frame length, link count, and mounting geometry.
The PC220-7 typically has a longer track frame and more chain links than the PC200-8. This means that while the undercarriage components—such as track rollers, sprockets, and idlers—may be dimensionally similar, the track assemblies themselves are not a direct swap. Modifications like adding extra links or adjusting tensioning brackets may be required.
Key Undercarriage Components and Terminology
Understanding the anatomy of an excavator’s undercarriage helps clarify compatibility issues:
  • Track frame: The steel structure that supports rollers and guides the track chain.
  • Track chain: A series of interconnected links that form the continuous loop around the undercarriage.
  • Carrier rollers: Located on top of the track frame, they support the upper portion of the track chain.
  • Track rollers: Positioned underneath, they bear the machine’s weight and guide the chain.
  • Idler: A wheel at the front of the track frame that maintains chain tension.
  • Sprocket: A toothed wheel at the rear that drives the chain via hydraulic motors.
While many of these parts are shared across models, the spacing, bolt patterns, and link counts vary. For example, the PC220-7 may use a 49-link chain, while the PC200-8 uses a 45-link chain. Attempting a direct swap without adjustment can result in misalignment, premature wear, or failure to tension properly.
Dealer Verification and Part Number Cross-Referencing
The most reliable method to confirm compatibility is through part number comparison. Komatsu dealers maintain detailed databases of component specifications. By cross-referencing the undercarriage part numbers of both machines, technicians can identify which components match and which require adaptation.
In one case, a contractor in Alberta attempted to fit a PC200-8 undercarriage onto a PC220-7 after purchasing a wrecked unit with intact tracks. After consulting a dealer, they discovered that while the sprockets and rollers were interchangeable, the track frame mounting points differed slightly. With minor welding and bracket adjustments, the swap was successful—but only after careful measurement and planning.
Real-World Lessons and Operator Stories
A fleet manager in Indonesia shared a story of retrofitting a Dash-8 undercarriage onto a Dash-7 machine during a remote mining operation. With limited access to parts and urgent downtime pressure, the team fabricated custom brackets and extended the track chain by four links. The machine ran for another 2,000 hours before needing further service.
In another example, a demolition contractor in Texas salvaged a PC200-8 undercarriage to rebuild a flood-damaged PC220-7. The project involved machining new bushings and modifying the idler mounts. The rebuilt machine performed reliably for three years, proving that with expertise and precision, cross-generation swaps are feasible.
Recommendations for Successful Swaps
For those considering undercarriage interchange between Komatsu Dash-7 and Dash-8 machines, here are practical guidelines:
  • Measure track frame length and link count before purchase
  • Consult OEM part numbers for sprockets, rollers, and idlers
  • Inspect mounting brackets and bolt patterns for alignment
  • Consider professional fabrication for bracket modifications
  • Use high-quality bushings and seals to prevent premature wear
  • Test chain tension and alignment before full operation
It’s also wise to document all changes for future maintenance and resale transparency.
Conclusion
While Komatsu Dash-7 and Dash-8 excavators share many design elements, their undercarriages are not universally interchangeable. With careful planning, part verification, and skilled modification, it is possible to retrofit components across generations. These swaps can extend machine life, reduce costs, and keep operations running—especially in remote or resource-constrained environments. The key lies in understanding the mechanical nuances and respecting the engineering behind each model.
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