750B vs TD-15C vs D6C: A Comparative Study of Mid-Size Dozers in Earthmoving History

[MikePhua]

Introduction to the Machines
The John Deere 750B, International Harvester TD-15C, and Caterpillar D6C represent a trio of mid-size dozers that shaped earthmoving operations from the 1960s through the 1990s. Each machine carries its own legacy, engineering philosophy, and operational quirks. While all three were designed for heavy dirt pushing, road building, and slope work, their differences in drivetrain, blade control, ergonomics, and support infrastructure have made them subjects of debate among seasoned operators.
Terminology Clarification

• Power Shift Transmission: A transmission that allows gear changes without clutching, often hydraulically actuated.
  
• Final Drives: Gear assemblies that transfer torque from the transmission to the tracks.
  
• Tilt Blade: A dozer blade that can be angled vertically to shape terrain more precisely.
  
• Lever Steer vs. Foot Steer: Refers to the method of directional control—hand levers or foot pedals.
  
• Double Tilt Angle Blade: A blade that can tilt both vertically and horizontally, enhancing grading flexibility.
  

TD-15C: Power and Practicality
The TD-15C from International Harvester is often praised for its balance, visibility, and raw pushing power. Operators note its ability to outperform the D6C in soft ground and steep grades, thanks to its wider stance and higher blade lift.

• Blade Control: Tilt integrated into the blade lever, allowing intuitive operation.
  
• Steering: Lever-based, offering better ergonomics than the D6C’s foot steer.
  
• Maintenance Access: Final drives can be removed in 2–3 hours without pulling track frames.
  
• Winter Operation: Tracks are easier to clean, reducing downtime in snowy conditions.
  
• Parts Availability: Still accessible, though support infrastructure is aging.
  

A Pennsylvania contractor recalled using TD-15Cs for winter road building in shale-heavy terrain. The machines lifted higher and tilted farther than their Caterpillar counterparts, making them ideal for shaping uneven surfaces.
D6C: Durability and Dealer Support
The Caterpillar D6C is a benchmark in dozer reliability. While it may lack some of the ergonomic refinements of the TD-15C, its parts support and service network are virtually unmatched.

• Transmission: 3-speed power shift, smoother than TD-15C’s 2-speed with hi-lo range.
  
• Blade Control: Foot tilt and foot steer, which some operators find less intuitive.
  
• Dealer Network: Caterpillar’s global presence ensures rapid parts delivery and technical support.
  
• Legacy: Many D6Cs are still in operation today, a testament to their build quality.
  

A retired operator in Ontario described the D6C as “the nicest Cat I ever ran,” citing its smooth transmission and consistent performance on steep grades. He noted that while TD-15Cs had more blade flexibility, the D6C’s simplicity made it easier to train new operators.
750B: The Quiet Contender
John Deere’s 750B is less frequently discussed but remains a capable machine. It features hydrostatic drive and modernized controls, making it more approachable for newer operators.

• Hydrostatic Transmission: Offers variable speed control and smoother operation.
  
• Visibility: Improved cab design compared to earlier models.
  
• Blade Control: Integrated joystick systems in later variants.
  
• Parts and Support: Deere’s dealer network is strong, though not as extensive as Caterpillar’s.
  

In British Columbia, a forestry crew used a 750B for trail building in mountainous terrain. Its hydrostatic drive allowed precise maneuvering around stumps and boulders, though it lacked the brute force of the TD-15C.
Ergonomics and Operator Experience

• TD-15C: Lever steer and blade tilt on the same control make for efficient operation.
  
• D6C: Foot controls can be fatiguing over long shifts, but the machine is intuitive once mastered.
  
• 750B: Joystick controls and quieter cab improve comfort, especially for newer operators.
  

Parts and Service Infrastructure

• Caterpillar: Unrivaled parts availability and dealer support.
  
• International Harvester: Parts still available, but support is limited and aging.
  
• John Deere: Strong support, especially in agricultural regions.
  

A former Finning sales rep noted that International nearly overtook Caterpillar in British Columbia during the 1960s and 70s—not due to superior machines, but because of dealership logistics. Cat’s wider distribution and faster parts delivery gave it the edge in remote areas.
Conclusion: Choosing the Right Machine
Each dozer has its strengths:

• TD-15C: Best for owner-operators who do their own maintenance and need blade flexibility.
  
• D6C: Ideal for those who prioritize dealer support and long-term reliability.
  
• 750B: Suited for operators seeking comfort and modern controls in mid-size applications.
  

Ultimately, the best choice depends on machine condition, price, and intended use. As one veteran operator put it: “Pick the one in the best shape for the best price—and know how to wrench on it.” These machines may differ in design, but they share a legacy of shaping landscapes and building infrastructure across North America.