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The Fairbanks-Morse Model 38D-8-1/8 is a two stroke cycle opposed
piston diesel engine. As the name implies, it is an 8-1/8 inch bore
engine that went into production in 1938 using a design based on
German technology. Fairbanks-Morse also built a smaller 5-1/4 inch
bore opposed piston engine with very similar design and features.
The engine featured a welded crankcase and an unusual cylinder liner
arrangement with two pistons per cylinder and no cylinder head.
The cylinders have no intake or exhaust valves, the air is admitted
and the exhaust is expelled through ports in the liner wall, with
the opening controlled by the travel of the pistons in the cylinder.
There are two fuel injection nozzles per cylinder, directly across
from each other on the liner wall, that inject fuel into a firing
chamber formed by the heads of the two pistons.
The Fairbanks-Morse OP engine was one of the engines able to pass
the mid-1930s U. S. Navy submarine qualification tests, and was
approved for application to fleet submarines. The GM-owned Winton
Engine Company, which became the Cleveland Diesel Engine Division
of GM in 1937, was another builder whose products passed the submarine
qualification tests, and they split the business for new construction
fleet submarines about equally with FM during the late 1930s and
through World War Two.
The Fairbanks Morse OP engine achieved an enviable record for reliability
in submarine service, and this made Fairbanks-Morse a strong contender
for postwar diesel marine engine sales. They also entered the diesel
locomotive market, compenting with Electro-Motive, ALCO, Baldwin,
Lima, and later General Electric. Despite the success of the OP
engine in submarine service, it was treated rather indifferently
under railroad maintenance, and suffered as a result. The FM product
tended to be regarded as an oddity on railroads, and this led to
a retreat from the US railroad market in 1953 and a complete exit
by 1960. Throughout this period, FM continued to build and sell
OP engines for marine and industrial use, and the engine remained
in widespread use in new construction for the U. S. Navy for many
decades. Today the Navy continues to run many OP engines and is
the largest remaining marine customer for the Fairbanks-Morse 38D-8-1/8.
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Above: The 12 cylinder Fairbanks Morse 38D-8-1/8
engine was an extremely powerful prime mover at the time of its
introduction, typically rated at 2400 horsepower in the Roots blower
version. The same engine with series turbocharging was rated at
up to 3600 horsepower.
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Above: This diagram shows the unusual arrangement
of the pistons and connecting rods in the Fairbanks Morse Opposed
Piston diesel engine. Two pistons share the cylinder, one connected
to the upper crankshaft and the other to the lower crankshaft. Timing
between the two crankshafts is maintained by a vertical drive with
a spring cushion pack.
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Above: Fairbanks Morse advertising in the marine
trade press took full advantage of the excellent record of their
engines in World War Two U. S. Navy Fleet Submarines. This wartime
FM ad tells of the missions of the USS Wahoo.
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Images courtesy of Fairbanks-Morse Company
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