O Trainmaster Diesel CNJ/Dmy.

Fairbanks Morse got into the locomotive business because it made
submarine engines. FM’s unique opposed-piston diesel engine powered
about half the U.S. Navy’s World War II submarine fleet and developed a
great reputation for reliability; the adaptation to railroad equipment
during and after the war seemed like a natural transition.

In the opposed-piston motor,
each cylinder had a piston at either end and the combustion chamber in
the middle. There were no valves or cylinder heads. Intake and exhaust
occurred through holes in the cylinder walls. The upper and lower banks
of pistons each powered a separate crankshaft, and the two crankshafts
were linked together to power the locomotive. While this sounds like a
complex way to build an engine, the O.P. diesel in fact had several
advantages over a conventional motor: less moving parts, terrific
acceleration, and about double the horsepower per cylinder.

In 1953 the O.P. engine
reached its zenith in the Trainmaster. Introduced at the Railroad
Manufacturers’ Supply Association show that year, FM’s new locomotive
took the show by storm. It was the most powerful single-motored diesel
locomotive of its era and had a brawny body to match its bold name.
Emblazoned in bright yellow and red, four Trainmaster demonstrators
barnstormed the country and walked away with any consist the railroads
threw at them. For one brief moment, Fairbanks Morse looked like a
contender.

Ultimately, however, the
opposed-piston engine proved ill-suited to locomotive use. The
bone-jarring railroad environment was much rougher on the motor than a
submarine cushioned by an ocean. The top crankshaft proved prone to oil
leakage. Perhaps most important, maintenance was a nightmare. Whereas a
single bad cylinder in an Electro-Motive diesel could be accessed by
pulling off one cylinder head, a cylinder repair in an O.P. engine
required removal of the top crankshaft and removal or disconnection of
the entire top bank of cylinders – which also meant the roof of the
locomotive had to come off. Ultimately, only 127 Trainmasters were sold
to 11 U.S. and Canadian railroads.

In the world of O gauge
railroading, however, the Trainmaster was a hit from the moment it went
on the market in the mid-1950’s. The engine’s massive size and
tremendous pulling power have made it one of the most-loved engines
among 3-rail operators for nearly half a century.