In 1937, an order of 30 Class S-2s was delivered from Baldwin. These were given road numbers 201 through 230. A second order of 10 Class S-2s were delivered from Baldwin in 1940 (road numbers 231 through 240). The Class S-2 Northerns weighed 490,450 lbs, had 74" drivers, 26 x 32 cylinders, 285 lbs psi and had a tractive effort of 70,800 lbs.
Because of wartime needs, another order of 10 (road numbers 260 through 269) Class S-3 Northerns was delivered in 1943 from the American Locomotive Company. This class was designed to have 74" drivers, 26 x 32 cylinders, 250 lbs psi boiler pressure and weighed 460,000 lbs and had a tractive effort of 62,040 pounds.
There are two survivors: number 261, which is operational and number 265 at the Illinois Railway Museum in Union, IL. When 261 is not running, it is stored at the old GN Shops near Minneapolis Junction in Minneapolis, MN.
|Class||Road Numbers||Year Built||Builder|
|S-1||250 (ex 9700)||1930||Baldwin|
As with most Class 1 locomotives built in this period, the firebox's heating surface area included a variety of structures and supplements. The combustion chamber contributed 122 sq ft (11.3 sq m), NIcholson thermic syphons (two in the firebox, one in the combustion chamber) 116.5 sq ft (10.8 sq m) and arch tubes 16.5 sq ft (1.5 sq m). The boiler's Coffin feedwater heater was to be "applied in recess provided in smoke box.". In addition, the firebox was fitted with a "smoke consuming device".
The 14" piston valves had 9" of travel.
This was the proof-of-concept Northern for the Milwaukee Road. Glischinski's account says that 9700 (works number was 61176 in December 1929) 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. Baldwin called it a "Modified Mountain".
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.)
Engines 203 and 231-240 used 105.5 sq ft (9.8 sq m) of circulators to supplement firebox heating surface instead of the 147 sq ft (13.65 sq m) of thermic syphons installed in the rest. See the photo provided on 16 September 2008 by "Mark D" to the Chaski Forum http://www.chaski.org/railfan/viewtopic.php?f=2&t=835; it illustrates splendidly the arrangement of the tubes and the firebricks that lay on top of them. The firebox also had a combustion chamber.
These forty S-2s operated mostly as freight haulers from Bensenville to Council Bluffs, Iowa or St. Paul, Minn. Occasionally they'd hook up to the westbound Olympian if it trailed more than twelve cars.
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
147 sq ft (13.66 sq m) of thermic syphons contributed to the firebox heating surface as did the combustion chamber. They had 14" (356 mm) piston valves with 7 1/2" (191 mm) of travel. Their backbones were one-piece cast steel beds from General Steel Castings Corporation. Boxpok drivers turned on Timken roller bearings, as did the front truck's wheels; rear truck and tender wheels used American Steel Foundries roller bearings.
Engines 203 and 231-240 used 105 sq ft (9.75 sq m) of circulators to supplement firebox heating surface; see Locobase 248 for the data.
These 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 twelve cars.
Firebox heating surface included 80.5 sq ft (7.48 sq m) 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. Like the 1940 batch from Baldwin, the boiler used circulators in place of thermic syphons. Glischinski's account says of this batch "...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 with retirements coming in 1954-1956.
|Specifications by Steve Llanso of Sweat House Media|
|Class||S1||S2 - circulator||S2 - thermic syphon||S3|
|Railroad||Milwaukee Road (CMStP&P)||Milwaukee Road (CMStP&P)||Milwaukee Road (CMStP&P)||Milwaukee Road (CMStP&P)|
|Number in Class||2||11||29||10|
|Road Numbers||9700/250||203, 231-240||201-202, 204-230||260-269|
|Locomotive Length and Weight|
|Driver Wheelbase (ft)||19.75||19.25||19.25||19.75|
|Engine Wheelbase (ft)||46.25||47.33||47.33||46.59|
|Ratio of driving wheelbase to overall engine wheebase||0.43||0.41||0.41||0.42|
|Overall Wheelbase (engine & tender) (ft)||88.33||92.04||96.04||95.50|
|Axle Loading (Maximum Weight per Axle) (lbs)||65,136|
|Weight on Drivers (lbs)||258,818||282,320||282,320||259,300|
|Engine Weight (lbs)||450,840||490,450||490,450||460,000|
|Tender Loaded Weight (lbs)||289,169||323,000||397,000||364,100|
|Total Engine and Tender Weight (lbs)||740,009||813,450||887,450||824,100|
|Tender Water Capacity (gals)||15,000||20,000||20,000||25,000|
|Tender Fuel Capacity (oil/coal) (gals/tons)||20||25||25||20|
|Minimum weight of rail (calculated) (lb/yd)||108||118||118||108|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in)||74||74||74||74|
|Boiler Pressure (psi)||230||285||285||250|
|High Pressure Cylinders (dia x stroke) (in)||28" x 30"||26" x 32"||26" x 32"||26" x 32"|
|Tractive Effort (lbs)||62,137||70,816||70,816||62,119|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.17||3.99||3.99||4.17|
|Firebox Area (sq ft)||549||536||578||505.50|
|Grate Area (sq ft)||103||106||106||96.20|
|Evaporative Heating Surface (sq ft)||5400||5468||5509||4478|
|Superheating Surface (sq ft)||2403||2336||2336||1438|
|Combined Heating Surface (sq ft)||7803||7804||7845||5916|
|Evaporative Heating Surface/Cylinder Volume||252.57||278.07||280.16||227.73|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||23,690||30,210||30,210||24,050|
|Same as above plus superheater percentage||31,034||39,273||39,273||29,822|
|Same as above but substitute firebox area for grate area||165,414||198,588||214,149||156,705|