The boiler, frame, trucks, and driving wheels were of the conventional type, the most notable visible difference between the locomotive and those of other types being the absence of cylinders, valve motion, and their accompanying parts. Because of the elimination of piston rods and other reciprocating parts it was possible to balance almost perfectly the driving wheels, thus permitting a higher operating speed than normally practical with a conventional locomotive. The weight of the locomotive alone was 580,000 pounds, and its forward tractive force was 70,500 pounds. A 6-8-6 wheel arrangement was employed, the driving wheel diameter was 68 inches, and a speed of 100 miles an hour was possible. The working steam pressure was 310 pounds per square inch. Bituminous coal served as the fuel. A detailed and well illustrated description of this locomotive appears in the magazine “Baldwin” (for the fourth quarter of 1944). The locomotive covered 103,050 miles in passenger service, and was then set aside on June 11, 1949, because it was in need of repairs to the firebox and flues, and also to the turbines, oil pumps, and gears. At that time all passenger service on the Pennsylvania was being changed to diesel-electric operation, so the locomotive was ultimately scrapped on May 29, 1952. [Illustration: Figure 80.—Model of Baldwin-Westinghouse geared steam-turbine locomotive, 1944.] General Motors Diesel-Electric Locomotive, 1945 A nonoperable model of a diesel-electric locomotive (figure 81) was given to the Museum (USNM 313163) by the New York Central System in 1947. This gray and black model, which is 33 inches long and is built to a scale of ¼ inch to the foot, represents the General Motors 2-unit diesel-electric _No. 4000-4001_ of the New York Central, a type placed in service with the Empire State Express in 1945 to replace the Hudson-type steam locomotives described on page 99. The model was especially built for the Museum’s collection, the builder being Edwin P. Alexander of Yardley, Pa. The overall length of the two full sized units is just over 140 feet and their combined weight is 646,000 pounds. Each end of each unit is supported by a 6-wheeled truck, and the wheel diameter is 36 inches throughout. Each unit is equipped with two General Motors 12-cylinder V-type 2-cycle diesel engines having a bore of 8½ inches and a stroke of 10 inches, and developing 1,000 horsepower at 800 revolutions per minute, a total of 4,000 horsepower for the two units combined. Each engine is directly coupled to a generator that supplies direct current to the two traction motors, geared, respectively, to the front and rear axles of its corresponding truck. No power is applied to the center axle, which is for weight distribution only. The joint tractive force of the two units is 108,950 pounds. [Illustration: Figure 81.—Model of General Motors diesel-electric locomotive, 1945.] PICTURE CREDITS