Komatsu D31P-17 Dozer and Its Role in Modern Earthmoving

[MikePhua]

The History Behind the D31 Series
Komatsu, founded in 1921 in Japan, has long been a global leader in construction and mining equipment. The D31 series of dozers was introduced as a compact yet powerful solution for grading, site prep, and forestry work. The D31P-17 variant, part of the Dash-17 generation, brought refinements in hydrostatic transmission, operator comfort, and fuel efficiency. With thousands of units sold across Asia, North America, and Europe, the D31P-17 became a staple in small contractor fleets and municipal operations.
The “P” in the model denotes a low ground pressure configuration, achieved through wider tracks and a longer undercarriage. This makes the machine ideal for soft terrain, wetlands, and areas where minimal soil disturbance is critical.
Terminology Note

• Hydrostatic Transmission: A drive system using hydraulic fluid to transmit power from the engine to the tracks, allowing smooth and variable speed control.
  
• Final Drive: The gear assembly that converts hydraulic or mechanical power into track movement.
  
• Track Frame: The structural component that supports the rollers, idlers, and track chains.
  
• Low Ground Pressure (LGP): A design feature that spreads machine weight over a larger surface area to reduce soil compaction.
  

Core Specifications and Capabilities
The Komatsu D31P-17 is powered by a Komatsu 4D95LE diesel engine, producing approximately 78 horsepower. Its operating weight is around 17,000 lbs, depending on blade configuration and optional equipment. Key dimensions include:

• Track width: 20 inches (LGP)
  
• Blade width: 8 feet (standard)
  
• Ground pressure: approximately 3.9 psi
  
• Maximum travel speed: 5.5 mph (forward), 5.5 mph (reverse)
  

These specs make the D31P-17 suitable for:

• Grading and finish work
  
• Clearing brush and small stumps
  
• Building access roads in soft terrain
  
• Maintaining trails and firebreaks
  

In a 2022 forestry project in Oregon, a D31P-17 was used to build access paths through marshy terrain. Its wide tracks prevented sinking, and the hydrostatic drive allowed precise maneuvering around tree roots and boulders.
Hydrostatic Drive Behavior and Maintenance Tips
The hydrostatic transmission in the D31P-17 offers excellent control but requires diligent maintenance. Common issues include:

• Hesitation during directional changes
  
• Whining noise under load
  
• Heat buildup in the transmission case
  
• Reduced travel speed over time
  

Preventive measures:

• Change hydraulic fluid every 500 hours using Komatsu-approved oil
  
• Replace filters at recommended intervals
  
• Inspect charge pump pressure and relief valve settings
  
• Monitor for leaks around the drive motor and final drive seals
  

A contractor in Louisiana reported sluggish travel on his D31P-17. After checking pressures, he discovered a clogged return filter. Replacing it restored full speed and reduced operating temperature by 15°F.
Undercarriage Wear and Rebuild Strategies
The undercarriage of the D31P-17 is robust but subject to wear, especially in abrasive soils. Key wear points include:

• Track chains and bushings
  
• Carrier rollers and bottom rollers
  
• Sprocket teeth
  
• Idler bearings
  

Signs of wear:

• Track slapping or popping during turns
  
• Uneven blade grading
  
• Excessive vibration at higher speeds
  
• Difficulty maintaining track tension
  

Solutions:

• Rotate pins and bushings every 1,000 hours
  
• Use sealed and lubricated track chains for longer life
  
• Replace rollers in matched pairs to maintain alignment
  
• Check sprocket wear using pitch gauge tools
  

In a municipal fleet in Manitoba, a D31P-17 underwent a full undercarriage rebuild after 4,800 hours. The team used aftermarket components and saved 30% compared to OEM parts, extending service life by another 3,000 hours.
Electrical System and Starting Reliability
The D31P-17 uses a 12V electrical system with a conventional starter motor and alternator. Common electrical issues include:

• Starter solenoid failure
  
• Corroded battery terminals
  
• Weak alternator output
  
• Faulty ignition switch
  

Recommendations:

• Use marine-grade terminals and dielectric grease
  
• Install a battery disconnect switch to prevent parasitic drain
  
• Upgrade to AGM batteries for better cold-start performance
  
• Test alternator output monthly using a clamp meter
  

A snow removal crew in Quebec retrofitted their D31P-17 with a block heater and upgraded battery cables. The machine started reliably even in -20°C conditions, reducing downtime during winter operations.
Operator Stories and Practical Lessons
In rural Georgia, a landowner used a D31P-17 to clear trails and build a pond. He appreciated the machine’s ability to float over soft clay without bogging down. After 2,000 hours, he replaced the blade tilt cylinder seals and added LED work lights for night grading.
Meanwhile, a contractor in New Zealand used the D31P-17 for vineyard development. Its compact size allowed it to work between rows, and the hydrostatic drive made it easy to train new operators. He noted that fuel consumption averaged 2.5 gallons per hour, making it economical for long shifts.
Conclusion
The Komatsu D31P-17 dozer remains a reliable and versatile machine for grading, clearing, and trail work. Its low ground pressure design, hydrostatic transmission, and compact footprint make it ideal for soft terrain and precision tasks. With proper maintenance and thoughtful upgrades, the D31P-17 can deliver thousands of hours of dependable service across diverse industries and landscapes. Whether clearing brush or shaping land, this dozer continues to prove its worth in the field.