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


Class Details by Steve Llanso of Sweat House Media

Class 828 (Locobase 2852)

See 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+.. 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.


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.


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.

These high-stepping Pacifics arrived with Walschaert gear and 14"-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.


Class F3 (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.


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, nine inches were lopped 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 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.


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.

The F4 repeated the F3 design (Locobase 9890), but rolled it 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


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.


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 in 1912. Six more F5s were derived from F4s (Locobase 2786) in 1914-1926. A few F5s became F5-bs with the mounting of 69" 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.


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.

Specifications by Steve Llanso of Sweat House Media
Class828F1F3F3F3-as/F1
Locobase ID2852 9894 9890 2785 9889
RailroadMilwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class3170702
Road Numbers828-830796/60001502-1551/6500-6549, 6100-61696500-49, 6100-69 /150-198151-152
GaugeStdStdStdStdStd
Number Built3170
BuilderRhode IslandSchenectadyAlco-BrooksMilwaukeeMilwaukee
Year18931889191019201940
Valve GearStephensonStephensonWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.48 / 4.1112.50 / 3.8114 / 4.2714 / 4.2714 / 4.27
Engine Wheelbase (ft / m)29.79 / 9.0827.75 / 8.4635.58 / 10.8435.58 / 10.8435.58 / 10.84
Ratio of driving wheelbase to overall engine wheebase 0.45 0.45 0.39 0.39 0.39
Overall Wheelbase (engine & tender) (ft / m)50.56 / 15.4149.94 / 15.2267.15 / 20.4767.39 / 20.5467.39 / 20.54
Axle Loading (Maximum Weight per Axle) (lbs / kg)28,660 / 13,00029,100
Weight on Drivers (lbs / kg)88,500 / 40,14390,000 / 40,823157,200 / 71,305169,380 / 76,830191,400 / 86,818
Engine Weight (lbs / kg)143,000 / 64,864131,000 / 59,421247,300 / 112,174263,866 / 119,688284,300 / 128,956
Tender Loaded Weight (lbs / kg)74,957 / 34,000116,764 / 52,963138,000 / 62,596156,000 / 70,760156,000 / 70,760
Total Engine and Tender Weight (lbs / kg)217,957 / 98,864247,764 / 112,384385,300 / 174,770419,866 / 190,448440,300 / 199,716
Tender Water Capacity (gals / ML)6000 / 22.737000 / 26.528500 / 32.208500 / 32.20
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.1010 / 9.1011 / 1013 / 11.80
Minimum weight of rail (calculated) (lb/yd / kg/m)49 / 24.5050 / 2587 / 43.5094 / 47106 / 53
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)78 / 198169 / 175379 / 200779 / 200779 / 2007
Boiler Pressure (psi / kPa)200 / 13.80180 / 12.40200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x660 (1)19" x 24" / 483x61023" x 28" / 584x71123.5" x 28" / 597x71123.5" x 28" / 597x711
Low Pressure Cylinders (dia x stroke) (in / mm)31" x 26" / 787x660 (1)
Tractive Effort (lbs / kg)17,129 / 7769.5919,211 / 8713.9731,874 / 14457.8233,275 / 15093.3033,275 / 15093.30
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.17 4.68 4.93 5.09 5.75
Heating Ability
Firebox Area (sq ft / m2)204.50 / 19153 / 14.22266 / 24.72266 / 24.72275 / 25.56
Grate Area (sq ft / m2)32.30 / 330.40 / 2.8348.80 / 4.5448.80 / 4.5459.80 / 5.56
Evaporative Heating Surface (sq ft / m2)1789 / 166.201745 / 162.173923 / 364.592897 / 269.242804 / 260.59
Superheating Surface (sq ft / m2)620 / 57.62620 / 57.62
Combined Heating Surface (sq ft / m2)1789 / 166.201745 / 162.173923 / 364.593517 / 326.863424 / 318.21
Evaporative Heating Surface/Cylinder Volume343.28221.56291.36206.10199.48
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation646054729760976011,960
Same as above plus superheater percentage64605472976011,51714,113
Same as above but substitute firebox area for grate area40,90027,54053,20062,77664,900
Power L16437659710,27418,37318,283
Power MT481.06484.80432.26717.42631.77

Specifications by Steve Llanso of Sweat House Media
ClassF4F4F5F5an/F2
Locobase ID9891 2786 2787 9888
RailroadMilwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)
CountryUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-2
Number in Class2525652
Road Numbers6600-66246600-66246300-6364801, 812
GaugeStdStdStdStd
Number Built2565
BuilderAlco-BrooksMilwaukee RoadseveralMilwaukee
Year1910192019111941
Valve GearWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14 / 4.2714 / 4.2714 / 4.2714 / 4.27
Engine Wheelbase (ft / m)35.50 / 10.8235.50 / 10.8235.33 / 10.7735.33 / 10.77
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.40 0.40
Overall Wheelbase (engine & tender) (ft / m)67.06 / 20.4467.40 / 20.5467.29 / 20.5167.29 / 20.51
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)160,100 / 72,620160,000 / 72,575160,000 / 72,575176,500 / 80,059
Engine Weight (lbs / kg)248,800 / 112,854253,000 / 114,759253,000 / 114,759281,300 / 127,596
Tender Loaded Weight (lbs / kg)134,550 / 61,031156,000 / 70,760156,000 / 70,760156,000 / 70,760
Total Engine and Tender Weight (lbs / kg)383,350 / 173,885409,000 / 185,519409,000 / 185,519437,300 / 198,356
Tender Water Capacity (gals / ML)7000 / 26.528500 / 32.208500 / 32.208500 / 32.20
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.1011 / 1011 / 1013 / 11.80
Minimum weight of rail (calculated) (lb/yd / kg/m)89 / 44.5089 / 44.5089 / 44.5098 / 49
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)79 / 200769 / 175373 / 185473 / 1854
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)23" x 28" / 584x71123" x 28" / 584x71125" x 28" / 635x71123.5" x 28" / 597x711
Tractive Effort (lbs / kg)31,874 / 14457.8236,493 / 16552.9740,753 / 18485.2736,010 / 16333.88
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.02 4.38 3.93 4.90
Heating Ability
Firebox Area (sq ft / m2)259 / 24.07259 / 24.07232 / 21.56232 / 21.56
Grate Area (sq ft / m2)48.80 / 4.5448.80 / 4.5448.85 / 4.5448.85 / 4.54
Evaporative Heating Surface (sq ft / m2)3910 / 363.383010 / 279.742977 / 276.672977 / 276.67
Superheating Surface (sq ft / m2)620 / 57.62620 / 57.62620 / 57.62
Combined Heating Surface (sq ft / m2)3910 / 363.383630 / 337.363597 / 334.293597 / 334.29
Evaporative Heating Surface/Cylinder Volume290.39223.55187.14211.79
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9760976097709770
Same as above plus superheater percentage976011,41911,43111,431
Same as above but substitute firebox area for grate area51,80060,60654,28854,288
Power L110,18016,88614,86316,821
Power MT420.54698.01614.39630.32

Photos

Reference