Atchison, Topeka & Santa Fe Other Articulated Locomotives in the USA

Class 1300/1398 (Locobase 420)

Data from "Record Breaking Freight and Passenger Locomotives for the Santa Fe," American Engineer and Railroad Journal, Volume LXXXIII [83], No 12 (December 1909), pp. 475-482; "Mallet Compound Passenger for the Atchison, Topeka & Santa Fe", Railway and Locomotive Engineering, Volume 22, No 12 (December 1909), pp. 520-521; and "Mallet Locomotives for the Atchison", Railroad Gazette, Volume XLVII [47], No 22 (26 November 1909), pp. 1018-1024. See also complete specs at DeGolyer, Volume 33, pp.184-189. (Thanks to Chris Hohl for his 19 July 2017 email pointing several errors in heating surface areas; and to (Thanks to Joshua Moldover for his 29 January 2021 email supplying Locobase with the RG citation, which contained several useful points to add to this entry.) Works numbers were 33708 in August 1909, 33776 in September.

An oddball wheel arrangement was only one of the peculiarities of these two locomotives. Chief among them was the array of heating elements in the boiler. The evaporative heating surface area is shown in the specs. A Jacobs smokebox superheater was squeezed in between the front face and the blast pipe; it offered very little extra energy to the steam it handled. Moreover, gases from the firebox passed through the flues, then reversed direction (!), traveling through a central flue and finally exiting through the stack.

In addition, the combustion chamber held a Buck superheater-reheater combination that included 798 sq ft (74.14 sq m) of area through which the steam exhausting from the HP cylinders picked up some heat before entering the LP cylinders as well as a superheater in front of the reheater. See the AERJ article for a complete description.

In addition, the pair used the feedwater heating system briefly adopted on a few engines. In the 1398s, this bundle of 314 2 1/4" tubes, each 84" (2,134 mm) long, amounted to 1,279 sq ft (118.29 sq m).

Another rarity was the Jacobs-Shupert firebox, a stayless alternative described more fully in Locobase 463. Although all four cylinders used piston valves, HP valves measured 13"(330 mm) in diameter while the LP cylinders used 15" (381 mm) diameter valves. And the front adhesion wheelbase came to 6 ft 4 in (1,905 mm) while the three-axle wheelbase farther back was 12 ft 8 in (3,860 mm).

Noting that these oil-burners were intended for passenger work, Angus Sinclair's R&LE effused:"This engine unquestionably marks an epoch in the development of the American passenger locomotive." In addition to its size, the design combined "to a degree not heretofore attained, those features which have proved of great value in reducing fuel and water consumption." RG added that the adoption of the unique wheel arrangement was "so applied that the engine can readily traverse 16 deg curves."

True that, but in each instance, the actual superheater, feed water heater, and combustion chamber were either dead-end variants or hopelessly compromised by other design elements. As a result, the duo was not successful in either passenger or freight service. Drury (1993) pronounced them "possibly the worst" of Santa Fe's Mallets. "The front (low-pressure) engine tended to slip, quickly using all the steam from the high-pressure engine, rendering itself useless and throwing all the load on the high-pressure engine."

But when converted to 4-6-2s in August and October 1915, respectively, along much more conventional lines, the pair served for decades (see Locobase 8274).