Choosing the Right Scraper for a Caterpillar D6H Dozer

[MikePhua]

The D6H and Its Capabilities in Towed Scraper Applications
The Caterpillar D6H Series II LGP (Low Ground Pressure) dozer was introduced in the late 1980s as part of Caterpillar’s push toward more versatile mid-size track-type tractors. With an operating weight of approximately 42,000 pounds and a net power rating around 185 horsepower, the D6H was designed for grading, pushing, and land clearing. The LGP variant features wider tracks and a longer undercarriage, improving flotation in soft soils but slightly reducing drawbar pull compared to standard configurations.
When paired with a towed scraper, the D6H becomes a powerful earthmoving tool capable of cut-and-carry operations in areas where motor scrapers may struggle due to traction or slope limitations. However, matching the right scraper to the dozer’s capabilities is essential to avoid overloading the transmission and hydraulic systems.
Recommended Scraper Sizes and Configurations
Operators with experience in scraper-dozer pairings recommend hydraulic pull-type scrapers in the 12 to 15 cubic yard heaped range for the D6H. While the machine may appear capable of pulling larger pans, such as the Caterpillar 435 (rated around 18 yards), doing so consistently can strain the drivetrain and reduce service life.
Preferred scraper models include:

• Ashland 155: Well-matched for the D6H, offering 14–15 yard capacity with hydraulic push-off
  
• Reynolds 70: A compact, efficient scraper with 12–14 yard capacity
  
• Rome 60 or 70 series: Durable pans designed for agricultural and construction use
  

Terminology:

• Heaped capacity: The maximum volume of material the scraper can carry when mounded above the bowl
  
• Dolly-style scraper: A pan with its own front wheels and hitch, reducing tongue weight on the towing tractor
  
• Push-off: A hydraulic mechanism that ejects material from the bowl without relying on gravity
  

Hydraulic Integration and Valve Configuration
Scrapers require hydraulic control for functions such as bowl lift, apron movement, and material ejection. The D6H may be equipped with auxiliary hydraulic lines originally intended for a ripper or winch. These lines can be repurposed for scraper control, but additional valves may be needed depending on the scraper’s complexity.
Hydraulic setup options:

• Use existing ripper circuit with a diverter valve to control scraper functions
  
• Add sections to the blade valve stack to create a dedicated scraper control bank
  
• Install a power-beyond line feeding an auxiliary valve block, either manual or electric
  

Modern scrapers often use sequence valves that allow two functions—such as apron and ejector—to operate from a single remote. Older pans may require three separate remotes, complicating integration.
One operator retrofitted a John Deere 750J with a four-valve stack to control a semi-U blade and scraper simultaneously. Another used a D7E with an electric spool valve for ripper control, adapting it for scraper use with minimal modification.
Transmission Considerations and Operational Limits
Pulling a scraper places significant load on the dozer’s transmission, especially during loading and uphill hauling. While the D6H’s powershift transmission is robust, prolonged use with oversized pans can lead to overheating, clutch wear, and reduced torque converter efficiency.
Best practices:

• Avoid scrapers exceeding 15-yard heaped capacity
  
• Monitor transmission temperature during extended pulls
  
• Use low gear and steady throttle to reduce shock loading
  
• Inspect drawbar and hitch points regularly for fatigue
  

In one case, a D7G pulled a 435 scraper for years, but the operator noted that even with more horsepower, the machine was often at its limit. A D6H would be under greater strain with the same load.
Field Experience and Practical Advice
Operators suggest starting with a 12–14 yard scraper and observing performance before upgrading. The D6H’s LGP configuration offers excellent traction but may limit drawbar force on firm ground. Dolly-style scrapers reduce tongue weight and improve maneuverability, making them a preferred choice for mid-size dozers.
Additional recommendations:

• Choose scrapers with good parts support and rebuild options
  
• Inspect hydraulic cylinders and hoses before hookup
  
• Consider terrain and haul distance when selecting scraper size
  
• Use a spotter or camera system when backing into tight cuts
  

One contractor in Saskatchewan noted that his D6H had capped hydraulic lines at the rear, originally intended for a ripper. By adding a diverter valve and checking the valve stack, he was able to control a scraper without major modifications.
Conclusion
Pairing a Caterpillar D6H with the right scraper requires balancing capacity, hydraulic compatibility, and transmission durability. While the machine can physically pull larger pans, long-term reliability depends on choosing a scraper that complements its power and weight class. With proper setup and cautious operation, the D6H becomes a versatile earthmoving platform capable of efficient cut-and-carry work across varied terrain. In scraper-dozer combinations, success lies not in brute force—but in smart matching and mechanical harmony.