Reviving the Undercarriage: Track Pin and Bushing Replacement on the Kato HD900

[MikePhua]

Introduction
The Kato HD900 excavator, a robust machine from the late 1980s, remains a reliable choice for demolition and earthmoving tasks. However, like all tracked equipment, its undercarriage components—particularly track pins and bushings—are subject to wear. When these parts deteriorate, operators face a critical decision: replace individual components or invest in a new track chain. This article explores the technical feasibility, repair strategies, and contextual insights surrounding track pin and bushing replacement on the HD900.
Understanding the Track Assembly
The track system on the HD900 consists of interconnected links, each joined by a pin and bushing. These components allow the track to articulate around the sprockets and rollers while maintaining structural integrity.
Key components include:

• Track Link: The steel segment that forms the track chain.
  
• Track Pin: A cylindrical shaft that connects two links and allows rotation.
  
• Track Bushing: A sleeve around the pin that reduces friction and wear.
  
• Press Fit Zone: The area where the pin is tightly fitted into the link.
  

Terminology Explained

• Flogged Out: A colloquial term indicating excessive wear or deformation, often seen in pin bores.
  
• Fabricated Replacement: Custom-made parts produced in a machine shop when OEM components are unavailable.
  
• Chain Link Assembly: The complete set of links, pins, and bushings forming one side of the track.
  

Symptoms of Wear and Damage
Operators may observe:

• Excessive slack or misalignment in the track
  
• Visible wear on bushings, exposing the pins
  
• Deformed pin bores in the links
  
• Uneven wear between left and right track chains
  

In one documented case, only one side of the HD900 showed significant wear, while the other remained nearly new—suggesting uneven load distribution or prior repair history.
Repair Options and Considerations
When facing worn pins and bushings, operators have several options:

• Replace Pins and Bushings Individually
  • Requires pressing out old components
    
  • May involve machining new bushings if OEM parts are unavailable
    
  • Suitable if link bores are intact
    
• Fabricate Custom Components
  • Machine shops can produce bushings and pins to spec
    
  • Cost-effective for limited repairs
    
  • Requires precise measurements and hardened materials
    
• Replace Entire Track Chain
  

• Simplifies installation and ensures uniform wear
  
• More expensive upfront
  
• Recommended if multiple links are damaged or deformed
  

Field Anecdote: Auction-Day Decision in South Australia
A mechanically inclined operator in Two Wells, Australia faced a dilemma before bidding on a used HD900 at auction. The machine’s right-side track chain was severely worn, with bushings ground down to the pins and one link “flogged out.” After consulting with a local supplier, he secured a new track chain at a reasonable price—opting for full replacement over piecemeal repair. His decision paid off, as the machine was soon put to work demolishing houses with minimal travel demands.
Historical Context: Track Chain Serviceability in 1980s Excavators
Excavators from the 1980s, including the HD900, were designed with field serviceability in mind. Track pins and bushings were often press-fit and replaceable, allowing operators to extend the life of their undercarriage without full chain replacement. However, as machines aged and parts became scarce, fabrication and retrofitting became common practices—especially in remote or cost-sensitive operations.
Related Case: East Coast vs. Local Support
While some operators struggled to find support for older Kato models, others found success with regional suppliers. One operator noted that while East Coast shops were too far away, a local dealer provided excellent service and sourced a new chain promptly. This highlights the importance of regional networks and supplier relationships in maintaining legacy equipment.
Best Practices for Track Component Replacement

• Inspect both sides of the track for wear symmetry
  
• Measure pin and bushing dimensions before fabrication
  
• Use hardened steel for custom bushings to resist wear
  
• Replace entire chains if multiple links show deformation
  
• Maintain detailed service records for future reference
  

Conclusion
The Kato HD900’s track pins and bushings are replaceable, but the decision to repair or replace depends on the extent of wear and available resources. With mechanical skill and supplier support, operators can restore undercarriage integrity and extend the life of these venerable machines. Whether through fabrication or full chain replacement, the HD900 proves that even decades-old iron can still move mountains—one link at a time.