FOUR-STROKE FAIRBANKS

Fairbanks-Morse 36A Engines

Fairbanks-Morse was a well-established engine manufacturer when they started the development of their first four-stroke, high-speed diesel in 1932. The term “high-speed” is relative, as the new design was rated at what today would be considered a yawn-inspiring 1200 rpm. When compared to Fairbanks Morse’s (F-M) other recently developed two-stroke diesels, which ran at 300 rpm or less, and the rest of the industry at the time, it was indeed a fast-spinning diesel powerplant. F-M had only recently made the change from low compression hot-bulb oil engines to full diesels, but they jumped into the game with both large and small engines.

The new diesel would emerge for 1934 as the Model 36A, with a 4.25 x 6.00-inch bore and stroke and rated for 10 horsepower per 85.12 cubic-inch cylinder. It was offered in one, two, three, four and six-cylinder inline configurations. A short time later, an inline eight-cylinder was added to the lineup. They were of the “en-bloc” design, meaning the blocks were cast in one piece. Each cylinder head was individual, however, and the engine used wet sleeved cylinders.

As the 36A design was being finalized for production, work began on a larger displacement version and it debuted in 1935 with a 5.5 x 7.5-inch bore and stroke and a 15 horsepower per cylinder rating at 900 rpm. The rpm rating was later upgraded to 1,200 and the power rose to 20 horsepower per cylinder. The larger version was offered only in four, six- and eight-cylinder inline arrangements and could be converted to run on natural gas. Both the larger and smaller engines carried the 36A designation, but each was delineated by its bore size, e.g. “36A41/4” or “36A51/2.”

The 36A engines found widespread use as stationary powerplants, generators, rail locomotive powerplants and for marine propulsion through the ‘30s and ‘40s. A similar en-bloc four-stroke engine debuted for 1938, the Model 46 with an 8 x 10.5-inch bore and stroke, but it only lasted until 1943.  We have been unable to determine exactly when production of the 36A ended but it was probably in the late 1940s.

“The term “high-speed” is relative, as the new design was rated at what today would be considered a yawn-inspiring 1200 rpm.”

In 1939, the 36A was joined by the smaller Model 45 line, which came in several varieties, with either 3.125 x 4-inch or 4.125 x 4.5-inch bore and strokes. The Model 45 came in several evolutions, one with a Lanova style combustion chamber and was mainly seen in one or two-cylinder configurations and was continued into the 1960s. Another F-M four-stroke of the era was the Model 48A, which came in a couple of bore and stroke combos. Though F-M was primarily known for its big two-strokes, they maintained a line of smaller four-strokes into the 1960s.

The engines shown are part of the Ken Doherty memorial collection. Ken began collecting F-M 36As in 1972 and the collection now has four, plus some of the other later F-M four-strokes. All are still in the hands of the Doherty and Hirschy families since Ken passed away in 2016. Grandson Nathan Hirschy has become the keeper of the F-M flame. These engines are brought regularly to the annual Tristate Engine and Tractor Show and can be seen there chugging away demonstrating the thrilling days of yesteryear.