Milwaukee Road 4-6-2 "Pacific" Locomotives in the USA

Class 828 (Locobase 2852)

Data from "Compound Passenger Locomotive for the Chicago, Milwaukee & St Paul", Railroad Gazette, Volume 25 (29 September 1893), p. 715. See also Paul T Warner, "The Chicago, Milwaukee, St. Paul & Pacific Railroad," published by Baldwin Locomotives; and James Dredge, A Record of the Transportation Exhibits at the World's Columbian Exposition of 1893 (New York: John Wiley & Sons, 1894), pp. 261+. (Thanks to Chris Hohl for his 13 January 2020 email and well-drafted spreadsheet, the latter correcting grate area, wheelbases, and weights as well as providing detailed data as well as sources.) Works numbers were 2880, 2912-2913 in April 1893 (road numbers 830, 828, and 829, respectively).

These were "Pacifics", but the trailing truck doesn't seem to have borne much of the firebox's weight. Indeed, the firebox was only 33 3/8" (848 mm) wide (a standard width for inside-the-frame fireboxes in those days). They were a cross-compound design that was displayed at the 1893 Columbian Exposition in Chicago. Warner reports that the design's career "...was comparatively short-lived, as it failed to measure up to service requirements" on the 85-mile expressway between Chicago and Milwaukee.

All three wound up on the Savannah, Florida & Western in March 1900 as their 104, 106, and 105, respectively. When the Atlantic Coast Line took over the SF&W, they placed the three in class J and numbered them 287, 289, and 288. All were rebuilt as class K-13 in May 1912 and all served until scrapped in May 1934.

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Class F1 (Locobase 9894)

Data from 1930ca Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and from Schenectady Locomotive Works, Illustrated Catalogue of Simple and Compound Locomotives (Philadelphia: J B Lippincott, 1897), pp. 80-81, and Paul T Warner, "The Chicago, Milwaukee, St. Paul & Pacific Railroad," published by Baldwin Locomotives.

This 4-6-2 wasn't really a "Pacific". Its trailing axle did not support much of the firebox and the boiler certainly wasn't in the same class as the 20th-Century engines that would bear the name.

Schenectady explained that this locomotive was "...designed to meet the requirements of limited weight on each driver." In other words, not intended to carry the bigger firebox and tall drivers of an express engine. The catalogue also noted "The forward truck has swing motion, while the trailing truck has swing motion and radius bar and is equalized with the drivers." So, clearly, another goal was the ability to negotiate a tight curve.

Warner reports that the engine "...rendered good service." He adds that later strengthening of the track allowed the railroad to remove the rear truck.

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Class F2 (Locobase 16626)

Data from "CM&StP Pacific Type Engine", Railway and Locomotive Engineering, Volume , No 5 (May 1905), p. 209; and MILW 1930ca Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange collection. See also Jim Scribbins, "Chicago, Milwaukee, St Paul & Pacific (Milwaukee Road) in George H Drury, Guide to North American Steam Locomotives (revised edition), (Waukesha, WI: Kalmbach Publishing,, 2015), p 136.

Superintendent of Motive Power A E Manchester and Mechanical Engineer J F De Voy designed this one-locomotive class, presumably to assess proportions of cylinder volume, firebox and grate, and driver diameter. Its inside link motion actuated 12" (305 mm) piston valves. Although the firebox seemed quite large when the short combustion chamber was included, the 851 could present only a relatively narrow grate.

Jim Scribbins indirectly confirmed the impression that this was a prototype by reporting that the Milwaukee ordered 50 Pacifics from Brooks (Locobase 9890) with considerably larger boilers, grate, 2" (50.8 mm) longer cylinder stroke, and taller drivers.

Never superheated, this lone engine went to the scrapper in 1929.

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Class F3 (Locobase 9890)

Data from 1930 & 1945 Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "Pacific Locomotives for the St. Paul," Railway Age Gazette, Volume 48 (13 June 1910), p. 1639. Works numbers were 47442-47471 in January 1910, 47472-47481 in February, 47482-47491 in March, 48714-48733 in September.

These high-stepping Pacifics arrived with Walschaert gear and 14" (356 mm)-diameter piston valves. According to the RAG report, they addressed a power shortage:

"Between Chicago and Milwaukee, 420 miles, two of the most important passenger trains are often composed of thirteen to fourteen cars, seldom less than ten, weighing 508 tons. The lighter through trains between Chicago and Omaha, 492 miles, carry seven cars of an aggregate weight of 372 tons. On the Chicago and Milwaukee division, 85 miles, trains of 750 tons, composed of fourteen cars, are common, and as many as sixteen cars have been run in one train.

"Till within the last year, a heavy class of Atlantic engine, having a total weight in working order of 210,400 lbs. and a tractive power of 22,200 lbs. was used in this service. The performance of the Atlantic engine, with these trains, considering its limitations of weight and power, was very creditable; but in ordering new passenger equipment last winter, the management adopted the Pacific engine "

They retained their saturated boilers for only a little while as the Milwaukee was quick to incorporate the advantages of superheat. See Locobase 2785.

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Class F3-as/F1 (Locobase 9889)

Data from 1930 & 1945 Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

These two engines were modified from the superheated F3 (Locobase 2785) in several important ways. First, the firebox saw a 20% growth in grate area by widening the firebox (but only a small increase in overall direct heating surface). Second, the shops lopped nine inches off the tubes and flues, which reduced overall evaporative heating surface area. Third, two of the three received a Hiawatha-like streamline casing based on the F7's (Locobase 183). The light porthole centered in a convex smokebox cover and sported a comb on its upper edge which served as the leading edge of a skyline casing that ran in a straight line over the swell of the boiler to the rear of the cab. The retractable coupler and skirts over the cylinders completed the Art Deco look.

These were placed on the Chippewa Hiawatha which ran from Chicago through Milwaukee and Green Bay to Ontagon, Michigan in the Upper Peninsula.

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Class F3-superheated (Locobase 2785)

Data from 1930 & 1945 Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

This first large class of Pacifics for the Milwaukee Road were among the first to use the DeVoy lateral-motion trailing truck; see Locobase 9890 for the saturated version.

When superheated, the class surrendered 178 small tubes for 28 large flues, but were otherwise not significantly modified. A few (154, 159, 167, 170, 173, 185) did eventually receive 24"-diameter cylinders.

The balance of the basic design was such that these engines shone in passenger service. Jim Scribbins (in Drury, 1993) comments these engines "were among the best of the road's passenger power. They could run 90 mph when worked to the utmost, and the last of them outlived all the Hudsons."

Three, including the two shrouded in a streamline casing for the Chippewa, were modified with larger grates; see Locobase 9889.

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Class F4 (Locobase 2786)

Data from 1930 & 1945 Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

OS Nock (RWC IV, pl 38) says these were identical to the F3s (Locobase 2785), except that they had 69" drivers for mountain sections. The tractive effort figure given by Jim Scribbins (in Drury, 1993) bears out that analysis.

Scribbins' roster shows 25 engines, as does his commentary. All the F4s soon were superheated and 6 were rebuilt with the larger 24" cylinders of the F5, which suggests that the boiler and grate dimensions in the basic design were more than ample. Retirements began in 1935 and continued in small numbers to 1954.

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Class F4 (Locobase 9891)

Data from 1930 & 1945 Milwaukee Road locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were

The F4 repeated the F3 design (Locobase 9890), but came out of the Milwaukee's own shops on relatively small drivers that made it more suitable for the more mountainous western sections. The Milwaukee was quick to incorporate the advantages of superheat. See Locobase 2786

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Class F5 (Locobase 2787)

Data from 1945 Milwaukee Road locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

This was the last big group of Pacifics for the Chicago, Milwaukee, St. Paul & Pacific and the first to be built with superheaters already installed. Jim Scribbins (in Drury, 1993) says that although they were delivered using 185 psi in the boiler, most eventually pressed their boilers to 200 psi as shown in the specifications. The Milwaukee's own shops built the first 15 F5s and Brooks supplied 50 more (works numbers 51134- 51139 in April 1912; 51140-51163 in May; 51331-51347 in June)..

Six more F5s were derived from F4s (Locobase 2786) in 1914-1926. A few F5s became F5-bs with the mounting of 69" (1,753 mm) drivers and developed 43,116 lb of tractive effort.

Like the other Pacifics, retirements began in the mid 1930s, but most endured until well after World War II.

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Class F5an/F2 (Locobase 9888)

Data from 1945 Milwaukee Road locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for spotting a typo that compared the F2 to the ...er ....F2.)

The F5s described in Locobase 2787 underwent many upgrades and detail tweaks. Two in particular joined the streamliner parade and are profiled in this entry. The streamlining profile resembled that of the F1 (Locobase 9889), which took its inspiration from the F7 4-6-4s (Locobase 183).

In addition to a higher weight than the other members of the class, changes included reducing the diameter of the cylinders by an inch and a half. The casing over the boiler and the front end shrouded the cylinders and Locobase wonders if cutting the cylinder size was necessary have it present a smooth line. (It wouldn't be the first time in railroading that practicality was sacrificed for vanity.)

The two engines served the Midwest Hiawatha's Manilla, Iowa to Sioux Falls, SD section through World War II. Afterward, the tandem was reclassified F2 and moved to the Wisconsin Valley line where they pulled the Northwest Hiawatha until their retirement in 1950.