Today, 02:11 AM
The Rise and Absorption of Wooldridge
Wooldridge was one of the pioneering names in American earthmoving equipment, emerging in the mid-20th century alongside giants like LeTourneau and LaPlant-Choate. Based in Sunnyvale, California, Wooldridge specialized in blades, rippers, cable controls, and eventually motor scrapers. Their early machines were known for complex cable reeving systems and roller chain final drives, with some of the first air-assisted cable controls in the industry.
In 1958, Wooldridge was acquired by Curtiss-Wright Corporation of South Bend, Indiana—a company better known for its aircraft engines and aerospace innovations. The acquisition marked a brief but ambitious attempt to enter the heavy equipment market. Wooldridge’s motor scrapers were rebranded under Curtiss-Wright and marketed aggressively, but the venture was short-lived. By 1963, Curtiss-Wright had discontinued the scraper line entirely, returning focus to its core aerospace business.
Terra-Cobras and Roto-Gear Steering
Wooldridge’s motor scrapers were branded as Terra-Cobras, while their towed pans were called Terra-Clippers. These machines featured a unique steering system known as Roto-Gear, which used twin hydraulic motors to apply torque through gear reduction to a bull gear attached to the scraper yoke. Unlike conventional hydraulic rams, this system offered precise control and reduced mechanical complexity.
Models included:
Survivors and Restorations
Despite their short production run, a handful of Curtiss-Wright and Wooldridge scrapers have survived. In Indiana, two machines—a Terra Cobra and a CW-28—were rescued from scrap and restored for farm use. In New Zealand, a CW-28 was converted into a towed scraper and attached to an Allis HD-15. Another CW-215 remained in service for years on the Alcan site in Wiri before being retired.
In California, collector Ed Akins preserved two Wooldridge scrapers—one painted in yellow and rust, the other in olive drab. These machines are among the few remaining examples of Wooldridge’s engineering legacy. Their survival is a testament to the durability of the designs and the dedication of enthusiasts who refuse to let history fade.
Terminology Clarification
After Curtiss-Wright exited the scraper business, MRS (Mississippi Road Supply) began producing their own bowls, having previously sourced them from Wooldridge. Hancock was contracted to build elevators for MRS machines. Eventually, Taylor Machine Works acquired MRS, continuing the lineage of heavy equipment manufacturing in Mississippi.
Lessons from the Field
Operators who worked with Curtiss-Wright scrapers recall their speed and power, especially during large-scale projects like the Auckland Airport construction. However, they also note the machines required frequent repairs—often due to rough handling rather than design flaws. The CW-215, for example, was known for its reliability but suffered from wear after years of hard use.
In one anecdote, a CW-215 was seen stripping topsoil while a TS-14 Wabco scraper worked nearby. The contrast between the two machines highlighted the rapid evolution of scraper technology in the 1960s.
Preservation Challenges and Recommendations
Finding parts for Wooldridge and Curtiss-Wright scrapers is exceptionally difficult. Most documentation has been lost, and few manufacturers support legacy components. For collectors and restorers:
Wooldridge and Curtiss-Wright scrapers represent a fascinating but nearly forgotten chapter in earthmoving history. Their innovative designs, brief production run, and scattered survivors offer a glimpse into a transitional era of mechanical engineering. While few remain, those that do are cherished by collectors and historians who understand their significance. In a world dominated by Caterpillar and Komatsu, the Terra-Cobras and CW-series machines remind us that innovation often comes from unexpected places—and that even short-lived ventures can leave a lasting legacy.
Wooldridge was one of the pioneering names in American earthmoving equipment, emerging in the mid-20th century alongside giants like LeTourneau and LaPlant-Choate. Based in Sunnyvale, California, Wooldridge specialized in blades, rippers, cable controls, and eventually motor scrapers. Their early machines were known for complex cable reeving systems and roller chain final drives, with some of the first air-assisted cable controls in the industry.
In 1958, Wooldridge was acquired by Curtiss-Wright Corporation of South Bend, Indiana—a company better known for its aircraft engines and aerospace innovations. The acquisition marked a brief but ambitious attempt to enter the heavy equipment market. Wooldridge’s motor scrapers were rebranded under Curtiss-Wright and marketed aggressively, but the venture was short-lived. By 1963, Curtiss-Wright had discontinued the scraper line entirely, returning focus to its core aerospace business.
Terra-Cobras and Roto-Gear Steering
Wooldridge’s motor scrapers were branded as Terra-Cobras, while their towed pans were called Terra-Clippers. These machines featured a unique steering system known as Roto-Gear, which used twin hydraulic motors to apply torque through gear reduction to a bull gear attached to the scraper yoke. Unlike conventional hydraulic rams, this system offered precise control and reduced mechanical complexity.
Models included:
- CW-226: 26 cubic yards
- CW-220: 20 cubic yards
- CW-215: 20 cubic yards
- CW-28: 15 cubic yards
- CW-320: 20 cubic yards
- CWD-221: 35-ton capacity
- CWD-214: 25-ton capacity
- CWD-321: 35-ton capacity
- CWT-30: 30 cubic yards
- CWT-8: 8 cubic yards
Survivors and Restorations
Despite their short production run, a handful of Curtiss-Wright and Wooldridge scrapers have survived. In Indiana, two machines—a Terra Cobra and a CW-28—were rescued from scrap and restored for farm use. In New Zealand, a CW-28 was converted into a towed scraper and attached to an Allis HD-15. Another CW-215 remained in service for years on the Alcan site in Wiri before being retired.
In California, collector Ed Akins preserved two Wooldridge scrapers—one painted in yellow and rust, the other in olive drab. These machines are among the few remaining examples of Wooldridge’s engineering legacy. Their survival is a testament to the durability of the designs and the dedication of enthusiasts who refuse to let history fade.
Terminology Clarification
- Motor Scraper: A self-propelled earthmoving machine with an integrated bowl for cutting, lifting, and transporting soil.
- Towed Pan: A scraper bowl pulled by a separate tractor or dozer.
- Bull Gear: A large gear used to transmit torque in heavy machinery.
- Cable Reeving: A system of pulleys and cables used to control scraper functions before hydraulic systems became standard.
After Curtiss-Wright exited the scraper business, MRS (Mississippi Road Supply) began producing their own bowls, having previously sourced them from Wooldridge. Hancock was contracted to build elevators for MRS machines. Eventually, Taylor Machine Works acquired MRS, continuing the lineage of heavy equipment manufacturing in Mississippi.
Lessons from the Field
Operators who worked with Curtiss-Wright scrapers recall their speed and power, especially during large-scale projects like the Auckland Airport construction. However, they also note the machines required frequent repairs—often due to rough handling rather than design flaws. The CW-215, for example, was known for its reliability but suffered from wear after years of hard use.
In one anecdote, a CW-215 was seen stripping topsoil while a TS-14 Wabco scraper worked nearby. The contrast between the two machines highlighted the rapid evolution of scraper technology in the 1960s.
Preservation Challenges and Recommendations
Finding parts for Wooldridge and Curtiss-Wright scrapers is exceptionally difficult. Most documentation has been lost, and few manufacturers support legacy components. For collectors and restorers:
- Photograph and catalog every component before disassembly
- Use reverse engineering to fabricate missing parts
- Network with other collectors to share knowledge and resources
- Preserve original paint and decals when possible
- Document oral histories from operators and mechanics
Wooldridge and Curtiss-Wright scrapers represent a fascinating but nearly forgotten chapter in earthmoving history. Their innovative designs, brief production run, and scattered survivors offer a glimpse into a transitional era of mechanical engineering. While few remain, those that do are cherished by collectors and historians who understand their significance. In a world dominated by Caterpillar and Komatsu, the Terra-Cobras and CW-series machines remind us that innovation often comes from unexpected places—and that even short-lived ventures can leave a lasting legacy.
