GE U36B

The GE U36B represented the culmination of General Electric's high-horsepower Universal Series locomotive program, entering production in January 1969 and continuing through December 1974. With a total production run of just 125 units, the type was built almost exclusively for two customers closely tied to the same corridor. The Seaboard Coast Line Railroad was by far the dominant purchaser, acquiring 108 locomotives for use in fast freight and intermodal service. The Auto-Train Corporation, which operated its distinctive automobile-carrying passenger trains largely over Seaboard Coast Line trackage, ordered an additional 17 units. When Auto-Train encountered serious financial difficulties, four of its locomotives were ultimately delivered instead to Conrail, which had those units fitted with AAR Type B trucks in place of the Blomberg trucks used on the Seaboard Coast Line fleet. Each locomotive carried a unit price of approximately $285,000. The U36B's operational life unfolded during a turbulent period for American railroading. The 1973 oil crisis sent fuel prices sharply upward, and railroads growing increasingly sensitive to operating costs began to question the economics of high-horsepower four-axle designs. With roughly 900 horsepower per axle, the U36B pushed against the practical limits of wheel adhesion that the relatively unsophisticated wheel-slip control technology of the era could manage. These factors collectively discouraged further development of similar designs, and General Electric would not return to the high-horsepower market in a significant way until the introduction of the Dash 7 series toward the end of the 1970s. The U36B thus stands as a transitional machine, marking both the peak and the effective conclusion of one era of American diesel locomotive development. Among the more colorful episodes in the type's history was the patriotic repainting of Seaboard Coast Line locomotive 1776 in a red, white, and blue scheme to commemorate the United States Bicentennial, which generated considerable public attention. The Auto-Train fleet was finished in that company's eye-catching purple, white, and red livery. During the exceptionally severe winter of 1976 and 1977, Amtrak leased six of the Auto-Train Corporation's U36B locomotives to help maintain power for the Chicago to Florida Floridian service. Today, a single example is known to survive in preservation, the former Seaboard Coast Line 1776, which is held at the Lake Shore Railway Museum in North East, Pennsylvania.

The U36B was a B-B diesel-electric locomotive powered by the 16-cylinder GE FDL16 prime mover, producing 3,600 horsepower and making it the most powerful four-axle entry in General Electric's Universal Series lineup. The locomotive measured 60 feet 2 inches in overall length, a dimension it shared with the visually nearly identical U33B, and carried a working weight of approximately 270,000 pounds. The Seaboard Coast Line units rode on Blomberg trucks sourced from traded-in EMD general-purpose locomotives, an economical reuse of serviceable running gear, while the Conrail examples received AAR Type B trucks. Traction was transmitted through a conventional DC electrical system. The Seaboard Coast Line locomotives were geared at an 81 to 22 ratio, enabling a maximum speed of 75 miles per hour, well suited to the fast freight assignments the railroad intended for them. A notable design feature shared across the high-horsepower Universal Series was the use of large bat-wing radiators mounted at the rear of the carbody to manage the substantial heat output of the FDL16 engine. The U36B and its six-axle counterpart, the U36C, were also engineered to work in conjunction with the MATE slug unit, a four-motor unpowered car that allowed a single U36B's electrical output to be distributed across a total of eight traction motors, effectively doubling tractive effort for demanding service. The Auto-Train locomotives lacked onboard steam generators, with passenger heating and comfort services instead provided by a dedicated steam generator car operated as part of the train consist.

—