EARLY PETERSON INNOVATIONS:
Quad D9s

Quad 9s at Oroville Dam - circa 1965-66

The Quad D9 design was the most practical and popular innovation to come out of Peterson's Special Services shop in the 1960s. It was the brainchild of Buster Peterson, who initiated most of Peterson Tractor's custom designs during the 40s, 50s, and 60s. The Quad’s doubled-horsepower increased loading capacity and cycle-times significantly, earning them a “standard” spot in the earthmoving industry for several years.

The machine debuted in the press in Western Construction Magazine's March 1964 issue:

"Peterson Tractor Co. of San Leandro has just unveiled their new Quad-Trac, a giant tractor composed of two CAT D9G units linked in tandem by a yoke-and-ball joint and run by a single operator. Development of this powerful heavyweight tractor has taken place over the past several months under the direction of R.A. “Buster” Peterson, Executive Vice President of Peterson Tractor, and widely know inventor of construction equipment.”

"With the constantly increasing size of earthmoving machinery, there is a demand for bigger and bigger tractors. We think the Quad-Trac may be the answer," explains Peterson. "The industry has just about reached the limit in size of single tractors. If we make them any bigger and heavier, they can’t be shipped intact. If we make them wider, they won’t ride in the scraper cut. Consequently, the Quad-Trac looks like one solution to the problem of more horsepower without increasing size and weight.”

A side-by-side unit was also available, but the tandem configuration was by far the most popular with its synchronized operating system that allowed one operator to run both machines simultaneously. The draft assembly and steering control system were patented by Buster in August 1966 and later purchased by Caterpillar.

The first Peterson Quad D9 machines debuted in West Virginia for SJ Groves. Subsequent models worked on the Oroville Dam (1965-66), and the San Luis Canal (mid-60s), to name a few. Peterson built a total of 10 kits for customers including SJ Groves, Peter Kiewit, Oman Construction, Buzz Haskins and Guy F. Atkinson. Caterpillar picked up the idea in the late 60s and started mass-producing their own DD9Gs from 1968 to 1980 when the higher horse-powered D10 was introduced.

Known as the Quads, Quad D9s,
Quad-Trac and Dual D9s

CAT bought Buster's patent and produced
their own version from 1968-80

Buster Peterson - Peterson's engineering genuis

Quad 9s on the San Luis Canal in the mid-60s