In 1899, inventor D.M. Hartsough built a 1-cylinder 8 hp tractor. Two years later, he built a 15 hp model. "Convinced of the possibilities for tractor power," writes C.H. Wendel in Farm Tractors: 1890-1980 Second Edition, "Hartsough built a 2-cylinder model in 1901. During 1905 a fourth model was built using a 4-cylinder engine with a 4-by-5-inch bore and stroke. This was a dramatic departure in tractor design and was the first successful tractor to be built with a 4-cylinder engine."
In 1906, the company was named Transit Thresher Co. Transit's earliest model was a 25-60 with a 6-by-8-inch bore and stroke. The tractor had no fenders.
In 1908, the company was renamed Gas Traction Co. By 1910, the Big Four moniker had been applied, referring to the huge size of the four cylinders, which were cast singly and mounted on the massive crankcase.
The bore of the 1910 tractor was increased to 6-1/2 inches for added power. Its rear wheels measured 96 inches in diameter with a 24-inch face (a later option offered wheels 99 inches tall and 30 inches wide). At about the same time, the radiator was modified and fenders were added. “The famous Big Four trademark consisting of the number ‘4’ within a circle was first used in December 1910,” Wendel writes. “By this time the company billed itself as the ‘first and largest builders of 4-cylinder farm tractors.’” FC
Read more on the Big Four tractors in Big Four Tractor Restorations: A Global Endeavor.