As David Mainey notes in his book Baltimore & Ohio Steam In Color, #5600 was clad in semi-streamlining and looked similar to an English-built machine. The basic premise behind the concept was to develop a more powerful,
rigid-framed locomotive that used two sets of powered drivers instead of one. It would also, in theory, reduce maintenance since it used
lighter and smaller main rods (four in all). Unlike the Pennsylvania Railroad, which
advanced the design further than any other company and is most often associated
with the duplex drive, the B&O's approach was a bit different by locating
the back set of cylinders (nearest the cab and under the firebox) behind
the rear drivers. This setup turned out to be one of the locomotive's glaring issues, among others. By placing the cylinders under the firebox they had a tendency to overheat as well as collect dirt and dust.
Emerson equipped the #5600 with his self-designed, water-tube firebox, which he had been testing since 1930 on Class T-1 4-8-2 #5510. The idea behind this special firebox was that it held a greater heating surface to the surrounding fire. For instance, according to SteamLocomotive.com regarding #5510 the water-tube firebox offered an 82% increase of the surface area (from 474 square feet to 866 square feet), "...including the 83 square feet of arch tubes." Other features of the #5600 included its high 350 pounds of boiler pressure, 76-inch main drivers, Walschaerts valve gear, and 18 x 26 1/2-inch cylinders (according to Mainey's book all four were integrally cast, the first of their kind). Additionally, the locomotive weighed 391,550 pounds (nearly 196 tons) and offered 65,000 pounds of tractive effort.
The B&O intended its 4-4-4-4 to be used in passenger service where it was employed through the early 1940s (during the 1939 New York World's Fair the George H. Emerson was put on display to the amazement of visitors). Unfortunately, numerous issues and the advancement of the diesel doomed the locomotive. The Emerson firebox proved problematic with vibration issues and it was not sufficiently insulated; in general it never offered significant advantages over a standard firebox. Additionally, the locomotive experienced problems related to its bearings that constantly kept it sidelined. Perhaps in time the B&O could have ironed out many of these setbacks but interest in steam was waning as diesels proved they were capable main line power.
When she was first conceived, the George H. Emerson held much promise. Aside from the intended advantages already mentioned its smaller and lighter main rods meant fewer counterbalance weights were needed and a short wheel base would have allowed it to operate all across the B&O's vast system. In service the #5600 was given mixed reviews by the crews that operated her; in general the locomotive offered a good ride but had a tendency to slip and would not always stop precisely. As problems mounted with #5600 it mostly sat in storage from the early 1940s until 1950 when it was finally scrapped. Perhaps most unfortunate is that the B&O did not preserve this unique locomotive since it was an experimental and the railroad often sent such interesting creations to its museum in Baltimore.
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Class N-1 4-4-4-4