The Milwaukee Road Class "A" was a class of high-speed,
streamlined
Streamlines, streaklines and pathlines are field lines in a fluid flow.
They differ only when the flow changes with time, that is, when the flow is not steady.
Considering a velocity vector field in three-dimensional space in the framework of ...
4-4-2 "
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
" type
steam locomotive
A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...
s built by the
American Locomotive Company
The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer of locomotives, diesel generators, steel, and tanks that operated from 1901 to 1969. The company was formed by the merger of seven smaller locomo ...
(ALCO) from 1935 to 1937 to haul the
Milwaukee Road's ''
Hiawatha
Hiawatha ( , also : ), also known as Ayenwathaaa or Aiionwatha, was a precolonial Native American leader and co-founder of the Iroquois Confederacy. He was a leader of the Onondaga people, the Mohawk people, or both. According to some account ...
'' express
passenger train
A passenger train is a train used to transport people along a railroad line. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) hauled by one or more locomotives, or may be self-propelled; self pr ...
s. Numbered from No. 1 to No. 4, they were among the last Atlantic type locomotives built in the United States, and certainly the largest and most powerful. The class were the first locomotives in the world built for daily operation at over , and the first class built completely streamlined, bearing their casings their entire lives. Although partially supplanted by the larger
class "F7" Hudson
Hudson may refer to:
People
* Hudson (given name)
* Hudson (surname)
* Henry Hudson, English explorer
* Hudson (footballer, born 1986), Hudson Fernando Tobias de Carvalho, Brazilian football right-back
* Hudson (footballer, born 1988), Hudso ...
s from 1937, they remained in top-flight service until the end. Locomotive No. 3 was taken out of service in 1949 and cannibalized for spare parts to keep the other three running until 1951.
History
![Hiawatha streamlined steam locomotive 1951](https://upload.wikimedia.org/wikipedia/commons/9/97/Hiawatha_streamlined_steam_locomotive_1951.JPG)
Designed for a 6½ hour schedule between
Chicago
(''City in a Garden''); I Will
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and St. Paul, the class proved capable of handling nine cars on a 6¼ hour schedule. The only change over the years, except bumps and dents in the casing, was the addition of a
Mars Light
Mars Lights are signal-safety lights used in the United States and built by Mars Signal Light Company for railroad locomotives and firefighting apparatus. Mars Lights used a variety of means to cause the light to oscillate vertically, horizontally ...
beneath the winged emblem on the nose in 1947.
They hauled the fastest scheduled steam-powered trains in the world. Running at 100 mph or greater was required to keep these schedules; the class A locomotives were designed to cruise at over and be able to achieve . A run with a
dynamometer car
A dynamometer car is a railroad maintenance of way car used for measuring various aspects of a locomotive's performance. Measurements include tractive effort (pulling force), power, top speed, etc.
History
The first dynamometer car was probably ...
behind the locomotive was made on May 15, 1935, by locomotive No. 2 between
Milwaukee
Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee is ...
and
New Lisbon, Wisconsin
New Lisbon is a city in Juneau County, Wisconsin, United States. The population was 1,748 at the 2020 census.
History
The site of New Lisbon was used as a seasonal winter encampment by Ho-Chunk people, who called it (anglicized to ''Wa Du Shuda ...
. Over a stretch the speed of was recorded. This was the fastest authenticated speed reached by a steam locomotive at the time, making No. 2 the rail speed record holder for steam and the first steam locomotive to top . There are reports, without evidence or accurate records, that these locomotives could exceed . Such speeds would have placed the class A in contention with the
LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable, ...
and German
BR 05 for the crown of fastest steam locomotive until that time, but no records have been unearthed. The successor
Milwaukee Road class F7
The Milwaukee Road's class "F7" comprised six (#100–#105) high-speed, streamlined 4-6-4 "Baltic" (Hudson) type steam locomotives built by the American Locomotive Company (ALCO) in 1937–38 to haul the Milwaukee's ''Hiawatha'' express passeng ...
was even more powerful, with a claimed top speed of .
The design was fairly conventional but unusual in some aspects. One goal was reducing reciprocating mass, which could not be completely balanced. This was the reason for the high boiler pressure of , which allowed smaller pistons. Reciprocating mass of the connecting rods was also reduced with the use of four, rather than the more usual six, driving wheels. The main rods connected to the first pair of driven wheels rather than the (more conventional) second; again, this reduced the reciprocating mass as well as providing more even power throughout the stroke. The large diameter
driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled ...
s reduced piston speed and made high speed less taxing on the machinery. The streamlined casings were designed to open easily for servicing; the front end had clamshell doors ahead of the
smokebox
A smokebox is one of the major basic parts of a steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is e ...
.
References
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External links
*{{commons category-inline, Milwaukee Road class A
Streamlined steam locomotives
A
ALCO locomotives
4-4-2 locomotives
Passenger locomotives
Railway locomotives introduced in 1935
Steam locomotives of the United States
Scrapped locomotives