EMD DDA40X

The DD40AX is a 6,600 hp (4.92 MW) D-D diesel-electric locomotive built by the General Motors EMD division of La Grange, Illinois for the Union Pacific Railroad. Nicknamed "Centennial" and "Big Jack", the DD40AX uses two diesel engines (each 3,300 hp (2.46 MW)) and is the most powerful single-unit diesel locomotive ever built, although more recent locomotive designs such as the GE AC6000CW and the EMD SD90MAC have come close. It is also the longest single-unit diesel locomotive ever built.

EMD DDA40X

The DD40AX is a 6,600 hp (4.92 MW) D-D diesel-electric locomotive built by the General Motors EMD division of La Grange, Illinois for the Union Pacific Railroad. Nicknamed "Centennial" and "Big Jack", the DD40AX uses two diesel engines (each 3,300 hp (2.46 MW)) and is the most powerful single-unit diesel locomotive ever built, although more recent locomotive designs such as the GE AC6000CW and the EMD SD90MAC have come close. It is also the longest single-unit diesel locomotive ever built.