Caterpillar 983 vs Komatsu D155S Comparing the Giants of Crawler Loaders

[MikePhua]

The Rise of Heavy Crawler Loaders in Earthmoving History
Crawler loaders emerged in the mid-20th century as a hybrid between bulldozers and wheel loaders, combining the traction of tracks with the versatility of a front-mounted bucket. Among the largest ever built were the Caterpillar 983 and the Komatsu D155S—machines that pushed the limits of mechanical design and operational scale. These loaders were designed for quarrying, dam construction, and industrial bulk handling, often weighing over 45 tons and equipped with buckets exceeding 5 cubic yards.
Terminology annotation:

• Crawler Loader: A tracked machine with a front bucket used for digging, loading, and material handling.
  
• Bucket Capacity: The volume of material a bucket can hold, typically measured in cubic yards (CY).
  
• Breakout Force: The force exerted by the bucket to penetrate material, influenced by hydraulic pressure and linkage geometry.
  
• Undercarriage: The track system including rollers, idlers, sprockets, and pads that supports and propels the machine.
  

Caterpillar 983 Engineering and Legacy
The Caterpillar 983 was introduced in the late 1960s and remained in production through the 1980s. It was not simply a modified D8 dozer but a purpose-built crawler loader with its own frame, hydraulic system, and loader linkage. With an operating weight exceeding 70,000 lbs and a bucket capacity around 5.5 CY, the 983 was a powerhouse in bulk loading applications.
Key features:

• Engine: Caterpillar D343, rated at approximately 325 hp
  
• Bucket: High-lift design with optional spade nose for bank penetration
  
• Transmission: Powershift with torque converter for smooth operation
  
• Undercarriage: Heavy-duty track frame with sealed and lubricated chains
  
• Application: Quarry loading, slag handling, dam construction
  

Strengths:

• Exceptional breakout force and stability on rough terrain
  
• Robust frame and loader arms designed for high-impact work
  
• Proven reliability in extreme conditions like steel mills and rock pits
  

Defects:

• Slow travel speed compared to wheel loaders
  
• High undercarriage wear and maintenance cost
  
• Limited visibility and operator comfort by modern standards
  

In Pennsylvania, a 983 was used to load boulders for artificial shoreline construction. The machine lifted massive rocks with ease but required frequent undercarriage service due to abrasive terrain.
Komatsu D155S Design Philosophy and Performance
The Komatsu D155S was developed as a direct competitor to the 983, borrowing heavily from the D155A dozer platform. With a similar operating weight and bucket capacity, the D155S featured a 350 hp engine and a mechanical layout that mirrored Caterpillar’s design, though with Komatsu’s own hydraulic and powertrain systems.
Key features:

• Engine: Komatsu SA6D170, rated at 350 hp
  
• Bucket: 5.9 CY with optional rock guards and wear plates
  
• Transmission: Powershift with planetary gear sets
  
• Frame: Reinforced loader chassis derived from dozer lineage
  
• Application: Mining, quarrying, and industrial bulk loading
  

Strengths:

• Slightly higher horsepower and bucket volume than the 983
  
• Durable loader arms and hydraulic cylinders for heavy-duty cycles
  
• Competitive pricing and parts availability in certain markets
  

Defects:

• Cloned design with limited innovation over the 983
  
• Slower hydraulic response and less refined operator controls
  
• Undercarriage wear similar to Caterpillar’s, with fewer aftermarket options
  

In Italy, a contractor used the D155S to move marble blocks in a quarry. The machine performed well but required custom bucket modifications to handle oversized stone.
Operational Tradeoffs Between Size and Speed
While both machines offered immense power, their size came with limitations. Travel speed was a major drawback—neither machine could match the mobility of a wheel loader like the Caterpillar 988. In applications requiring frequent repositioning, the tracked loaders lagged behind. However, in confined or unstable terrain, their traction and breakout force were unmatched.
Comparative notes:

• Wheel loaders excel in speed and maneuverability
  
• Crawler loaders dominate in traction and digging power
  
• Excavators surpass both in precision and cycle efficiency for trenching
  

Recommendations:

• Use crawler loaders for dense material loading, demolition, and boulder handling
  
• Pair with dozers for site prep and material push
  
• Avoid long-distance travel cycles—use haul trucks or wheel loaders for transport
  
• Monitor undercarriage wear and maintain track tension regularly
  

In Missouri, a contractor retired his 983 in favor of a 988 wheel loader for limestone loading. The speed improvement was dramatic, but the 983 remained unmatched in bank penetration.
Why These Machines Disappeared from Production
Neither the Caterpillar 983 nor the Komatsu D155S is manufactured today. Their disappearance reflects a shift in construction strategy and equipment economics. Excavators and wheel loaders have taken over most of their roles, offering better fuel efficiency, faster cycles, and lower maintenance costs. The complexity and cost of maintaining a 70,000 lb tracked loader became unjustifiable for most contractors.
Factors contributing to obsolescence:

• High undercarriage and hydraulic maintenance
  
• Operator fatigue and limited cab ergonomics
  
• Fuel consumption exceeding 10 gallons per hour
  
• Competition from more versatile machines like excavators and wheel loaders
  

Recommendations:

• Preserve legacy machines for niche applications like quarry boulder loading
  
• Retrofit older units with modern cab insulation and hydraulic upgrades
  
• Use tracked loaders in demolition and brush clearing where traction matters
  
• Document service history and maintain parts inventory for long-term use
  

In Canada, a steel mill kept a 983 in service for slag loading due to its durability and resistance to heat. The machine was retrofitted with high-temperature hoses and a reinforced cab.
Conclusion
The Caterpillar 983 and Komatsu D155S represent the pinnacle of crawler loader design—machines built for brute strength and endurance. Though no longer in production, their legacy lives on in the stories of operators who moved mountains, loaded boulders, and reshaped landscapes. In the world of heavy equipment, size is only part of the story. It’s the character of the machine—and the skill of the operator—that defines true capability.