Legacy of the International TD-24 and TD-25 Dozers

[MikePhua]

The Rise of International Harvester in the Earthmoving World
In the mid-20th century, International Harvester (IH) emerged as a formidable competitor in the heavy equipment industry. Originally known for agricultural machinery, IH expanded into construction with its line of crawler tractors. Among its most iconic models were the TD-24 and TD-25, introduced in the 1940s and 1950s respectively. These machines were designed to rival Caterpillar’s D8 and D9 series, offering high horsepower, rugged undercarriages, and innovative features for their time.
The TD-24, launched in 1947, was powered by a 12-cylinder, 109-horsepower diesel engine and weighed over 40,000 pounds. It was one of the first dozers to feature torque converter technology, which allowed smoother power transfer and reduced operator fatigue. The TD-25 followed in the early 1950s with increased horsepower and improved hydraulics, eventually evolving into the TD-25C and TD-25G variants by the 1970s. IH sold thousands of these machines globally, with strong markets in North America, Australia, and Eastern Europe.
Parts Legacy and the Challenge of Preservation
Today, the TD-24 and TD-25 are considered vintage iron—machines that evoke nostalgia and mechanical admiration. However, maintaining them poses challenges. Many units have been retired, scrapped, or cannibalized for parts. Yet, some owners still operate them in logging, land clearing, or as part of historical collections.
Among the most sought-after components are:

• Final Drives: These gear assemblies transfer torque from the transmission to the tracks. Their condition is critical, as worn gears or bearings can lead to catastrophic failure.
  
• Cylinder Heads: Responsible for housing valves and combustion chambers, heads must be crack-free and properly seated. Magnetic particle inspection (MPI) is often used to detect hidden fractures.
  
• Track Frames and Rollers: These wear items are essential for maintaining alignment and traction.
  

In one case, a family in Northern Minnesota discovered three final drives and several cylinder heads while cleaning out a workshop once owned by a lifelong IH mechanic. Though the parts’ condition was unknown, their rarity made them valuable to restorers and collectors.
Evaluating and Selling Vintage Components
When assessing vintage dozer parts, several steps are recommended:

• Clean and inspect for visible damage, rust, or wear
  
• Use MPI or dye penetrant testing for cracks in heads
  
• Rotate gears manually to check for binding or chipped teeth
  
• Photograph all angles and label part numbers if visible
  
• Compare with IH parts catalogs or service manuals
  

Selling options include:

• Listing on regional equipment classifieds with “best offer” terms
  
• Contacting vintage machinery clubs or restoration groups
  
• Reaching out to international buyers, especially in Australia or Eastern Europe where TD-series machines are still in use
  
• Connecting with the Historic Construction Equipment Association (HCEA), which maintains a network of IH enthusiasts
  

Scrapping should be a last resort. Even if parts seem obsolete, they may help someone restore a rare machine or serve as templates for reproduction.
Global Interest and the Australian Connection
Interest in TD-series dozers extends beyond North America. In Australia, where IH machines were widely used in mining and agriculture, collectors actively seek parts to restore operational units. One such enthusiast had been searching for a TD-24 cylinder head for years, hoping to revive a machine used in bush clearing during the 1960s. When a lead surfaced from overseas, it sparked a chain of emails, photos, and shipping arrangements—demonstrating the global reach of vintage iron.
Preserving the IH Legacy
International Harvester ceased production of construction equipment in the early 1980s, eventually merging into Navistar. Yet the legacy of the TD-24 and TD-25 lives on through restorers, museums, and field operators who value mechanical simplicity and raw power. These machines represent an era when engineering was tactile, repairs were hands-on, and every bolt told a story.
To preserve this legacy:

• Document serial numbers and service history
  
• Share photos and stories with historical forums
  
• Donate rare parts to museums or educational programs
  
• Host local machinery shows featuring operational TD-series dozers
  

In 2016, a restored TD-25 was featured at a heritage equipment expo in Ohio, drawing crowds who marveled at its size and sound. The owner, a retired contractor, had spent five years sourcing parts from four states and two countries. His dedication underscored the passion that vintage machinery inspires.
Conclusion
The International TD-24 and TD-25 are more than machines—they are mechanical monuments to a bygone era of industrial progress. Whether buried in a barn or roaring back to life at a showground, their parts and stories continue to circulate among those who understand their value. For families uncovering old components, the decision to preserve, sell, or donate is not just practical—it’s a tribute to the legacy of those who built and operated these iron giants.