Santa Fe No. 5000

As early as 1919, the Santa Fe converted a class 3800 2-10-2 locomotive into a 2-10-4, creating the world's first locomotive with this wheel arrangement. This was done by exchanging the rear carrying axle for a bogie, while slightly increasing the boiler's heating surface. However, since the firebox was not enlarged, the gains in performance were limited and it remained a one-off. However, since the Texas & Pacific had built the first 2-10-4 in series from 1925, this type was called “Texas”. It was not until 1930 that the Santa Fé built engine number 5000 directly as 2-10-4, which soon became known as “Madame Queen”.

The boiler was designed to be significantly more powerful with a grate area of more than 120 square feet, three thermic syphons and a total heating surface increased by 34%. This made the locomotive significantly heavier and reached a maximum axle load of more than 76,000 pounds. The tender was also very large with a total weight of 375,000 pounds, which was carried on six axles. It held 20,000 gallons of water and 46,000 pounds of coal. Compared to its predecessor, it could tow 15% more weight in 9% less time with 17% less coal per ton-mile. It formed the basis for the classes 5001 and 5011 and remained in service just as long as these, i.e. until 1957.