The story of the double-wide dozer begins with a simple problem: heavy earthmoving projects on steep, growing cities needed more muscle than standard machines offered. In response, the West Coast dealer Peterson Tractor Company adapted the familiar D8 by combining powerplants to create a larger, more capable machine during the 1950s. That custom approach produced three original twin-dozer units in that decade, each built to push larger volumes of material across the demanding terrain of San FranciscoNorthern California and Oregon.
Decades later the original trio no longer survives, so the team at Peterson CAT commissioned a fourth example as part of the company’s 80th anniversary celebration. Completed in 2016 the new unit faithfully follows the mechanical concept of the originals: two linked inline-six powerplants driving a single, wide blade arrangement to maximize pushing capacity for heavy construction work.
Why the twin D8 concept mattered in the 1950s
In the mid-20th century the standard D8 had established itself as a workhorse, but some contractors needed something beyond the factory lineup. Peterson Tractor Company, already a major Caterpillar dealer on the West Coast, answered by effectively mating two D8 drivetrains behind a single blade. Each of the original custom machines used two D13000 engines, each displacing 1,246 cubic inches. Together they delivered the extra push required on steep grades and heavy fills.
At the time, each D13000 produced roughly 200 hp a figure that today sounds modest but represented significant pulling and pushing force when combined into a twin configuration. The concept was, in essence, a way to scale available technology for larger projects before larger factory models were produced. Peterson Tractor built three of these double-wide D8s, and they were put to hard use in the field until none remained by later years.
The 2016 recreation and its mechanical features
To commemorate Peterson CAT’s milestone, the company and supporting collectors recreated the lost machine. The anniversary build replicated the twin-engine layout with two linked D13000 units and retained key operational features from the originals. Notably, each diesel engine could be started using separate gasoline-powered pony motors a practical starting method for large diesels of that era. The two engines were mechanically linked, but operators could separate them through a lever that engaged or disengaged the inboard steering clutches—allowing flexible control and the ability to operate from either side of the cab depending on the best sightline to the blade.
The rebuilt dozer was assigned a build number—serial number 004—reflecting its place as the fourth machine following the three historic units of the 1950s. While the mechanical layout mirrored the originals, the project also served as a living exhibit of mid-century heavy-equipment ingenuity: combining existing components to create a machine tailored to regional construction needs.
Contributors and parts sourcing
The recreation was a collaborative effort. Collectors and enthusiasts, including noted Caterpillar collectors Ed Akin and Glen Ghilotti worked with the owning family, the Doyle family to find the necessary parts and to bring the concept to fruition. The project demonstrates how private collectors and dealers can preserve engineering heritage by reconstructing rare machines when originals are lost.
Exposure, decline and restoration in Hillsboro
After completion, the anniversary dozer spent time parked outside the Peterson CAT facility in Hillsboro, Oregon. Over the course of eight years sitting outdoors, UV exposure oxidized paint surfaces and water intrusion damaged one of the engines. Long-term outdoor storage took a visible toll, creating corrosion and mechanical deterioration that left the machine in need of refurbishment.
At that point Nate Degerstedt took charge of the restoration process. He oversaw work to address the water-damaged engine and to revive the twin powerplants, returning the machine closer to the original operating condition. For anyone interested in hearing the story directly from those involved, a detailed account and interview are available from a filmed segment uploaded by SEFILMS via YouTube in which Degerstedt recounts the origins and the hands-on efforts to preserve serial number 004.
Although the three 1950s originals did not survive into the present, the Peterson CAT recreation and its later restoration preserve a unique chapter of heavy-equipment history. The twin D8 dozer illustrates a practical, field-driven approach to engineering: when off-the-shelf equipment fell short, dealers and contractors adapted existing components to meet extraordinary project demands.
