Milwaukee Road class EP-2
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Milwaukee Road The Chicago, Milwaukee, St. Paul and Pacific Railroad (CMStP&P), often referred to as the "Milwaukee Road" , was a Class I railroad that operated in the Midwestern United States, Midwest and Pacific Northwest, Northwest of the United States fr ...
's class EP-2 comprised five
electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or gas ...
s built by
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
in 1919. They were often known as Bipolars, which referred to the
bipolar electric motor A bipolar electric motor is an electric motor with only two (hence ''bi-'') poles to its stationary field. They are an example of the simple brushed DC motor, with a commutator. This field may be generated by either a permanent magnet or a field ...
s they used. Among the most distinctive and powerful electric locomotives of their time, they epitomized the modernization of the Milwaukee Road. They came to symbolize the railroad during their nearly 40 years of use, and remain an enduring image of mainline electrification.


Design

In 1917, following the tremendous success of the 1915 electrification of the Mountain Division, the Milwaukee Road decided to proceed with electrifying the Coast Division. As part of this project it ordered five new electric locomotives from General Electric for $200,000 apiece. Their design was radically different from the
boxcab A boxcab, in railroad terminology, is a locomotive in which the machinery and crew areas are enclosed in a box-like superstructure (from boxcar). It is a term mostly used in North America while in Victoria (Australia), such locomotives have been ...
locomotives previously provided by General Electric for the initial electrification of the Mountain Division two years earlier. The Milwaukee Road was the only railroad to order this design of locomotive from GE. The most remarkable mechanical improvement was arguably the traction motors used on the new locomotives. They were known as
bipolar motor A bipolar electric motor is an electric motor with only two (hence ''bi-'') poles to its stationary field. They are an example of the simple brushed DC motor, with a commutator. This field may be generated by either a permanent magnet or a field ...
s, because each of the locomotive's 12 motors had only two field poles, mounted directly to the locomotive
frame A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...
beside the
axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...
. The motor armature was mounted directly on the axle, providing an entirely gearless design. This design was almost entirely noiseless, as it eliminated not only gear tooth growl, but also the whine of higher-RPM electric motors typically used in standard nose-mounted applications. The EP-2s were not the first electric locomotives to use bipolar motors, which had first been designed by Asa F. Batchelder for the
New York Central The New York Central Railroad was a railroad primarily operating in the Great Lakes and Mid-Atlantic regions of the United States. The railroad primarily connected greater New York and Boston in the east with Chicago and St. Louis in the Midw ...
S-motors over a decade earlier, but at the time they were the largest. The layout of the bipolars was unusual as well. The locomotive carbody consisted of three sections. A small center section contained a
boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central h ...
for heating passenger cars, while the larger end sections contained the locomotive's electrical equipment and operator cabs in distinctive round-topped hoods. The locomotive's frame was split into four sections, hinged at the joints, with the two middle sections attached to the end sections of the locomotive body. There were twelve sets of
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, plus a single idler axle at each end, for a 1B-D+D-B1 wheel arrangement. All buffering forces were transmitted through the locomotive frame. The bipolars were designed to be able to pull any Milwaukee Road passenger train singly, and were originally delivered without
multiple unit A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train contr ...
controls. General Electric claimed a top speed of for the locomotives, but the Milwaukee Road rated them at . They were rated at continuous with a continuous
tractive effort As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. In railway engineering, the term tr ...
of and a starting tractive effort of .


Service history

When the Bipolars were introduced, their modernity and distinctive design made them the most famous of the Milwaukee Road's electric locomotives. They came to symbolize the '' Olympian'', the railroad's premier train from
Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...
to
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. Their unique appearance and power made them ideal for publicity purposes, and there was a series of demonstrations in which a Bipolar was able to out-pull contemporary
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. During a short period of testing on the Mountain Division, the EP-2s were shown to be less expensive to operate than the GE and Westinghouse electric locomotives then in use. The five EP-2s, numbered 10250-10254, were placed into regular service in 1919 on the Coast Division. The Milwaukee Road saw immediate cost savings over the steam locomotives previously in use, as the Bipolars could run from Tacoma to
Othello ''Othello'' (full title: ''The Tragedy of Othello, the Moor of Venice'') is a tragedy written by William Shakespeare, probably in 1603, set in the contemporary Ottoman–Venetian War (1570–1573) fought for the control of the Island of Cypru ...
without stopping for servicing and could haul trains up
grades Grade most commonly refers to: * Grade (education), a measurement of a student's performance * Grade, the number of the year a student has reached in a given educational stage * Grade (slope), the steepness of a slope Grade or grading may also r ...
that had required
double-heading In railroad terminology, double heading indicates the use of two locomotives at the front of a train, each operated individually by its own crew. The practice of triple-heading involves the use of three locomotives. The practice of multi-headin ...
steam engines. The Bipolars operated on the Coast Division from 1919 to 1953, for most of that period without any serious rebuilding. In 1939 they were renumbered E1-E5. In 1953 all five of the EP-2s, which were 35 years old and worn out from heavy wartime service, were heavily rebuilt by the Milwaukee Road at a cost of about $40,000 per locomotive. The rebuild included additional traction motor shunts for increased speed,
roller bearings In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing (mechanical), bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, Groove (engineering), g ...
, multiple unit capability, flash boilers, and streamlining. The E5, rebuilt in the Tacoma Shops as the prototype, performed as advertised, but went
over budget A cost overrun, also known as a cost increase or budget overrun, involves unexpected incurred costs. When these costs are in excess of budgeted amounts due to a value engineering underestimation of the actual cost during budgeting, they are known ...
, so the Milwaukee Shops were tasked with rebuilding the other four Bipolars. Unfortunately the Milwaukee Shop forces, unaccustomed to working on electric locomotives, did a "poor job" in the opinion of Electrification Department Head Laurence Wylie. (Wylie's successor, T. B. Kirk, stated that he saw a group of disconnected wires in a newly rebuilt EP-2 bundled together and tagged with a written message, "We don't know where these go".) Afterwards the Bipolars were prone to electrical fires and failures, despite repeated attempts by Tacoma Shops to correct them. Between 1954 and 1957 the Bipolars saw decreased use, and in mid-1957 were transferred off the Coast Division to the Mountain Division. Their problems persisted; moreover, passenger train speeds in the Rockies (over in some locations) were generally in excess of the Coast's top speed of , further exacerbating these problems. Between 1958 and 1960 all five were gradually retired, by which time they had received the
Union Pacific The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...
-inspired yellow and gray passenger paint scheme. In 1962 all except for E2 were towed to Seattle and scrapped. Locomotive E2 was donated to the
National Museum of Transportation The National Museum of Transportation (NMOT) is a private, 42-acre transportation museum in the Kirkwood suburb of St. Louis, Missouri. Founded in 1944, it restores, preserves, and displays a wide variety of vehicles spanning 15 decades of Americ ...
in
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in 1962 and moved there that year. It has remained on static display ever since, and has been fully restored to its appearance immediately after its 1953 rebuilding.


References

* * * * * {{GE electrics 3000 V DC locomotives EP-2 General Electric locomotives Passenger locomotives Electric locomotives of the United States Preserved electric locomotives Railway locomotives introduced in 1919 Gearless electric drive Standard gauge locomotives of the United States