08-27-2025, 01:57 PM
Machine History and Background
The Caterpillar 666B stands as one of the largest and most powerful twin-engine motor scrapers ever built. Introduced in the 1960s as part of Caterpillar’s 600 series motor scrapers, the 666B was designed to handle massive earthmoving tasks, particularly in mining and large construction projects. Its robust stature and impressive hauling capacity made it a legend in high-volume dirt moving and reshaping earth landscapes.
Engines and Powertrain
The Caterpillar 666B scraper remains an icon of heavy earthmoving, known for its twin-engine powertrain, massive capacity, and durability in demanding environments. Its influence on modern earthmoving equipment design is profound, pushing the limits of speed and volume transport. Although retired from production decades ago, the 666B continues to inspire awe and represents a pinnacle in the era of large motor scrapers.
The Caterpillar 666B stands as one of the largest and most powerful twin-engine motor scrapers ever built. Introduced in the 1960s as part of Caterpillar’s 600 series motor scrapers, the 666B was designed to handle massive earthmoving tasks, particularly in mining and large construction projects. Its robust stature and impressive hauling capacity made it a legend in high-volume dirt moving and reshaping earth landscapes.
Engines and Powertrain
- The 666B is equipped with twin turbocharged diesel engines: a 550 HP Caterpillar D346 diesel engine powers the tractor unit, while a 400 HP D343 engine runs the scraper bowl.
- This setup ensures maximum torque and horsepower for tackling hilly terrain, heavy loads, and long haul distances.
- A semi-automatic 8-speed power shift transmission in the tractor delivers smooth shifting and power distribution.
- Hydraulic retarder systems help preserve service brakes during long downhill hauls by applying hydraulic drag.
- The machine features a robust three-axle configuration offering unmatched stability and weight distribution.
- The front axle features hydraulic-assisted steering with a pivot pin allowing vertical movement for rough terrain adaptability.
- A universal hitch connects tractor and scraper, permitting lateral oscillation of up to 22 degrees on either side while including anti-jackknifing stops to enhance operational safety.
- The scraper bowl holds approximately 40 cubic yards of material struck and 54 cubic yards when heaped, with capacity increased further by sideboards.
- Empty operating weight is around 61 tons, with loaded weight reaching approximately 118 tons.
- Length measures approximately 56 feet 8 inches, width near 14 feet 4 inches, and height about 14 feet 4 inches.
- Tires come in massive sizes: 18×25 for the steering axle, 37.5×39 for the tractor drive axle, and a monumental 37.5×51 for the scraper axles.
- The 666B was primarily designed for high-speed hauling on level or mild grades, capable of reaching speeds over 42 mph fully loaded.
- The heavily hydraulic-operated scraper bowl uses double-acting cylinders for rapid loading and dumping.
- Operator comfort was considered with a left-of-center seating position providing excellent visibility and accessible controls.
- Some late-model 666Bs came equipped with Roll-Over Protective Structure (ROPS) cabs.
- The 666B excelled in large-scale earthmoving applications such as open-pit mining, major highway construction, and large infrastructure projects.
- Its ability to move vast quantities of material quickly made it invaluable in areas like coal mines across Wyoming and Nevada and large railroad realignments.
- Despite being phased out in the late 1970s, the 666B remains legendary among operators and enthusiasts for its sheer size, power, and performance.
- Because of its fuel consumption and the increasing demand for more efficient machines, scrapers of this magnitude were the last of their kind from any manufacturer.
- Motor Scraper: Self-propelled earthmoving machine combining a tractor and scraper unit to dig and haul soil.
- Power Shift Transmission: Transmission that allows shifting without clutching, enhancing operational efficiency.
- Hydraulic Retarder: A device that slows the machine using hydraulic drag to reduce brake wear.
- Universal Hitch: A pivoting connection allowing movement between tractor and scraper.
- Sideboards: Extensions on scraper bowls to increase hauling volume.
The Caterpillar 666B scraper remains an icon of heavy earthmoving, known for its twin-engine powertrain, massive capacity, and durability in demanding environments. Its influence on modern earthmoving equipment design is profound, pushing the limits of speed and volume transport. Although retired from production decades ago, the 666B continues to inspire awe and represents a pinnacle in the era of large motor scrapers.
