Class S1 (Locobase 247)

Data from 1930 Locomotive Cyclopedia tables. Also see Steve Glischinski's article on the MIlwaukee's generations of 4-8-4s at http://www.261.com/history/generations.shtml, last accessed 23 September 2007.

Firebox fitted with combustion chamber and thermic syphon, boiler had feedwater heater. This was the proof-of-concept Northern for the Milwaukee Road, Glischinski's account says that 9700 (works #61176) entered service in 1930 from Baldwin as a trial horse against the powerful F6 4-6-4s then in service. He contends that the S1 was a stretched F6 in any case.

For the moment, the Milwaukee's passenger trains made do with the F6 and the 9700 was put to work pulling 5,000-ton freights on its own. In 1934, the 9700 began working passenger trains between Avery, Idaho and Othello, Washington. In February 1938, the West Milwaukee shops duplicated the 9700, by then renumbered 250, and rolled out the 251. (Glischinski notes that it was the last new locomotive from that facility.)

Class S2 (Locobase 248)

Data from 1947 Locomotive Cyclopedia tables.

Firebox heating surface included 105 sq ft of circulators. Even before theWest Milwaukee shops produced the 251 (see Locobase 247), the Milwaukee Road had gone to Baldwin for its definitive Northerns. The first 28 were produced in October 1937 through February 1938 (62089-62117). Ten more (62344-62353) came in March-April 1940.

These forty S-2s operated mostly as freight haulers from Bensenville (West Milwaukee) to Council Bluffs, Iowa or St. Paul, Minn. Occasionally they'd hook up to the westbound Olympian if it trailed more than 12 cars.

Retired 1953-1956.

Class S3 (Locobase 249)

Data from 1947 Locomotive Cyclopedia tables. Also see Steve Glischinski's article on the MIlwaukee's generations of 4-8-4s at http://www.261.com/history/generations.shtml, last accessed 23 September 2007.

Firebox heating surface included 80.5 sq ft of circulators.

The last of the Milwaukee Road's Northerns, this design pieced together a Rock Island frame, a Delaware & Hudson boiler, and a Union Pacific tender. One change in the boiler was the use of circulators in place of thermic syphons. Glischinski's account says of these "...an Alco ad touted them as 'the last word in 4-8-4 design.' They featured roller bearings, special compensating lateral driving-box devices, and precision firing equipment."

Four were later converted to oil-burning and the engines saw out steam in both freight and passenger service.