Robert G. LeTourneau

Stocktonian Was the Greatest Inventor of Earthmoving Equipment

LeTourneau on 1915 Holt 75 Caterpillar with his first scraper, 1921. Photo: San Joaquin County Historical Museum.

Abraham Grunauer’s Whitehall Ranch near Tracy hired Robert G. LeTourneau (1888-1969) in 1919 to repair its old Holt scraper. LeTourneau recalled in his autobiography, “As I look back on it…, if that scraper had been in perfect working condition, I might never have gone into the manufacture of earth-moving equipment. …By the time I had it running I thought it was the most fascinating piece of machinery I had ever encountered.”  

LeTourneau’s first workshop in south Stockton, 1922-29. Photo: San Joaquin County Historical Museum.

In 1920, LeTourneau borrowed one thousand dollars and bought a used 1915 Holt 75 Caterpillar Tractor, rented a Schmeiser scraper made in Davis, California, and began grading farmlands in San Joaquin County. 

A couple years later (1922), LeTourneau established a workshop in south Stockton on Moss Avenue (now Ninth Street), west of McKinley (the old Highway 50 entrance to Stockton). “R.G.” was a mechanical genius and began building and continually improving his own scrapers in the yard of that tiny shop. In the book, Caterpillar Dozers and Tractors, Randy Leffingwell points out that for LeTourneau, “each model was a prototype; the successive model, the one that was supposed to be the ‘working version,’ contained enough improvements to be yet another prototype. And so it went for decades.” 

From his little shop, about a mile and one-half south of the Holt plant, LeTourneau received the first of his 299 patents—he is now recognized as the world’s greatest and most prolific inventor of earthmoving equipment.  

Robert G. LeTourneau completed many earthmoving projects as a contractor in the 1920s and early 1930s. His projects included the highway from Boulder City, Nevada, to the Colorado River that enabled the building of Hoover Dam. In California, LeTourneau built the racetrack at the San Joaquin County Fairgrounds, the Patterson Canal in adjacent Stanislaus County, the Lake of the Woods and Starr Bend levees near Marysville, the north approach to the Benicia railroad bridge, the Newhall Cut-off road, and the Santiago Dam in Orange County (at the time, the largest earthfill dam ever built).

Robert G. LeTourneau. Photo: R.G. LeTourneau. Heritage Center

In his autobiography, LeTourneau reflected:

Without knowing it at the time, I was in a remarkable position in 1928, and one that gave me a big advantage over my competitors. As a contractor I was able to see all the weaknesses of the earth-moving machinery then in use, and as a manufacturer I was able to do something about it. [The pieces of equipment developed] were built exclusively to help me get ahead as a contractor, but they were to become the foundation of our company. 

In 1929, LeTourneau incorporated his Stockton business as R.G. LeTourneau, Incorporated. When the company started manufacturing equipment for direct sale, rather than for its own use, it outgrew its south Stockton workshop and yard. In 1930, R.G. LeTourneau, Incorporated moved to a new welded metal building in northeast Stockton, at the corner of East Roosevelt Street and School Avenue (near the junction of Wilson Way and Waterloo Road). Four years later, the company doubled the size of that plant and added a brick office building. 

In 1935, Caterpillar Tractor Co. convinced LeTourneau to move his operations to Peoria, Illinois, near the Caterpillar plant in East Peoria. The move made sense because R.G. LeTourneau, Incorporated supplied many implements used on Caterpillar tractors and had a marketing agreement with Caterpillar Tractor Co. The New Deal public works programs building roads, bridges, dams, and other infrastructure during the Great Depression in the 1930s created new markets for Caterpillar tractors. R.G. LeTourneau, Incorporated flourished as one of several official implement manufacturers for Caterpillar. 

R.G. Letourneau, Inc. manufacturing plant in northeast Stockton, 1930-35. Photo: San Joaquin County Historical Museum.

Robert G. LeTourneau invented many earthmoving machines, including a number of scrapers, bulldozer blades, and power control units and cable-operated systems, as well as an electric wheel drive, and the two-wheeled Tournapull tractor. He was the first to use electric-arc welded construction and low-pressure heavy-duty rubber tires on scrapers.

Leffingwell pointed out that “A large percentage of earth-moving science and technology sprang from [Robert G. LeTourneau’s] mind. It grew from his fingertips and took shape under his welding torches. He often was years ahead of everyone else….”   

R.G. LeTourneau, Incorporated grew to become an international corporation with manufacturing plants in Toccoa, Georgia (established in 1938); Rydalmere, Australia (1941); Vicksburg, Mississippi (1942); and Longview, Texas (1946). The company built 70 percent of the heavy earthmoving equipment used by the Allies in World War II. 

Robert G. LeTourneau was the president, chairman of the board, and chief engineer of R.G. LeTourneau, Incorporated from 1929 to 1966. He also founded LeTourneau University in Longview, Texas. 

Tournapull tractor model Super C with Carryall scraper, 1941. Photo: R.G. LeTourneau Heritage Center

(This article was condensed from: “Earthmoving Capital of the World: San Joaquin County’s Agricultural Needs Led to Decades of Innovation,” The San Joaquin Historian, summer 2017, published by the San Joaquin County Historical Society

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