Atchison, Topeka & Santa Fe / Santa Fe 2-8-4 "Berkshire" Locomotives in the USA

Class 4101 (Locobase 469)

Data from table in 1930 Locomotive Cyclopedia and diagram presented at [] /c4193-1.gif and the Kansas Memory digital collection of Santa Fe diagrams at [] . See also DeGolyer, Volume 77, pp. 2+ and 41+. (Thanks to Chris Hohl for his 6 November 2024 email referencing his research into this class as noted below and supplying a revised wheelbase and correcting the axle load.) Works numbers were 59952-59955, 59977-59978, 59988-59992 in April 1927 and 60029-60032 in May.

Described by Drury (1993) as "basically good 1922 engines with a 1927 wheel arrangement." An assessment borne out by the tube-to-flue ratio and relatively meager supplementary heating surface areas. Boiler had Elesco H-5 feedwater heater and 44 sq ft (4.1 sq m) of arch tubes contributing to the direct heating surface. Steam was admitted through 15" (381 mm) piston valves.

4115 was delivered with a boiler designed to be pressed to 250 psi (17.25 bar) with a cutoff set to 68%. This combination of stroke length and boiler pressure yielded the same tractive effort as the others, but the piston load was calculated to increase by 15%. Other slight differences included a valve travel of 9 1/2" (241 mm), 1/2" (12.7 mm) longer than the valves in the others.

Chris Hohl reports an increase to 275 psi in boiler pressure that was applied first to the 4115 and later to the entire class; calculated tractive effort rose to 86,554 lb (39,260 kg or 385 kN). Also, he notes that the entire class was converted to oil burning, which required oil tankage. He explains his reasoning as follows:

"The 4101 class 2-8-4s & the 3751, 3752, & 3761 class 4-8-4s (#3751-3764) were all built with the same tenders (Baldwin tender drawing #1670, 20 tons of coal, 15,000 gallons of water, weighed 283,000 lbs. loaded, and had a wheelbase of 31' 3_"). Furthermore, when #3751 & #3762-3764 were converted to oil ...they had inserts put into their original tenders that would carry 5,000 gallons of oil." Power system (engine & tender) wheelbase increased slightly to 81' 10 1/8" (24.94 m).

Class 4193-modified (Locobase 16668)

Data from ATSF 1953 Locomotive Diagrams Steam Assorted supplied in 2016 by Allen Stanley from his extensive Rail Data Exchange collection. See also George H Drury, Guide to North American Steam Locomotives-Revised edition (Waukesha, WI: 1993, rev ed 2015), p. 85 (Thanks to Leo Drake for his 26 February 2024 suggesting the addition of a Locobase entry dedicated to the 1947-1948 changes to the 4197 and 4193; and to Chris Hohl, whose 27 April 2020 email supplied information and a spreadsheet providing details on the 4197 .) .

The B&M's sold seven of its T-1 2-8-4 Berkshires (Locobase 47) to the Santa Fe in 1945. The Santa Fe's shops updated two of the class beginning in 1947. When modified, the boiler now sported the distinctive cylindrical feedwater heater mounted above the smokebox and in front of the stack. Valve motion used limited cutoff.

Seven of these were sold to the Santa Fe in July and August 1945 as that railroad's 4193 class. Some sources say the class was converted to oil-burning but the Santa Fe diagrams available to Locobase show all seven as coal burners. All but one remained unmodified and left service in 1949.

The Santa Fe rebuilt the 4197 at the Topeka Shop in1948. Differences included an Elesco feed water heater, boiler pressed to 270 psi (18.62 bar), smaller 27" (686 mm) diameter and longer 32" (813 mm) stroke. The cylinder volume and boiler pressure matched the Santa Fe's own 4101 class and may reflect a reuse of 4101 components.

The 4197 used cast steel cylinders,and multiple-bearing crosshead. The new combination of boiler pressure and cylinder volume raised tractive effort to a calculated 84,980 lb (378.01 kN). The Santa Fe, however, rated the engine at 70,100 lb (31,797 kg or 311.89 kN) tractive effort, which suggests a much lower operating pressure of about 225 psi (15.52 psi) for the 4197. Chris Hohl's review of several Santa Fe diagrams determined that the Santa Fe "generally used a constant ranging from 70%-75%" as part of its tractive effort calculation, which would have resulted in the lower tractive effort.

The unconverted engines lasted only a short time on the Santa Fe and were sent to the ferro-knacker in October and November 1949. The 4197's rebuild gave her more life; she was scrapped with the other 2-8-4s in 1954.