Atchison, Topeka & Santa Fe 2-10-10-2 Locomotives in the USA

Class Santa Fe Mallet (Locobase 418)

Data from DeGolyer, Volume 37, pp. 277+.. See also "The Largest Locomotive", Railway Age Gazette, Volume 50, No 15 (14 April 1911), p. 906. (Many thanks to Dan Watson for his 10 May 2016 email noting the 3001's movie role -it was a real treat to see this locomotive in action, and thanks to Chris Hohl for his 6 October 2017 email noting this class's oil-burning setup. Thanks to Greg Mills for his 2 May 2018 email spotting an incorrect wheebase.)

Known as Santa Fe Mallets, these are among the few 2-10-10-2s built. Ten in number, the engines were cobbled together by the Santa Fe using existing 2-10-2 engine units united with low-pressure enginee units supplied by Baldwin. The rear HP cylinders, which remained from the earlier configuration, retained their relatively capacious 15" (381 mm) piston valves, but were bushed to 28". New LP cylinders used 13" (330 mm) piston valves..

Ahead of the distinctive ribbed Jacobs-Shupert firebox came the long boiler. (Locobase has yet to locate a diagram of this boiler's innards. The following description reflects his best understanding of its complicated layout)

Like other Santa Fe Mallets, the actual tube length of the 377 fire tubes was relatively short. Ahead of the front tube sheet, a 91" (2,311 mm) long combustion chamber contained the feedwater heater, which was stuffed with 500 2 1/4 tubes that aggregated 2,637 sq ft. A single 6" (152 mm) diameter tube passed through the center of the bundle. It ended at the beginning of a 32" (813 mm) combustion chamber, which connected the front of the feed water heater and the low-temperature LP superheater. This connector needed "suitable expansion flanges" to accommodate the initial steam pipes and HP exhaust pipes.

The superheater section featured two parts: a low-temperature superheater (that was nowhere nearly as efficient as later superheater designs) and a reheater that together added a further 2,360 sq ft (219.25 sq m). According to the specs, the Santa Fe superheater bundle included 500 2 1/4" tubes, each 96 1/2"(2,451 mm) long, and amounted to 874 sq ft (81.20 sq m) of superheating surface area. The Santa Fe reheater--which accepted exhausted HP steam and renergized it before letting it into the LP cylinder valves--was credited with 1,466 sq ft (136.20 sq m). As with the feedwater heater, a single 6" diameter tube passed through the center of the superheater bundle.

Baldwin also designed and built the unusual "turtleback" tender that improved rearward vision.

Overall, the design was unsuccessful and the engines were converted back to 2-10-2 simple-expansion locomotives in 1915-1918; see Locobase 5389.

But before they shucked their oddball dress, says Dan Watson's email of 10 May 2016, one of them got into the movies: "Regarding the AT&SF 3000 class 2-10-10-2 locomotives, the 3001 appeared in the theatrical film "The Hazards of Helen" Episode #3: "The Leap from the Water Tower" (1915) as available on youtube ..." Helen Holmes and Pearl White (of the Perils of Pauline) were widely known actresses whose serial jeopardy (including the literal cliffhangers that entered the language) for dozens of episodes. Locobase can recommend several of the Hazards episodes for the clear reproduction and fascinating railroading detail.