The 4HJ4m16yfo Class is a class 4-8-10-4 Mallet locomotives designed by Gustav Othmar at the Eastern & Atlantic's Charlotte Works.
The Eastern & Atlantic had a large amount of freight moving between cities of the Northeast Corridor, and much of this freight ran straight through cities like New York and Boston, close to the street. After the Flushing Collision of 1938, the Eastern & Atlantic decided that some of it's gigantic articulated locomotives were unfit for running so close to the street, and thus decided to design some new boxcab locomotives.
This resulted in the 4HJ4m16yfo Class, which combined the pulling power of a 4-axle power unit and a 5-axle one. This layout proved succesful, and the unusual design was produced from 1940-1943, producing 15 locomotives.