On July 14, 2017, Santa Fe No. 3751 prepares to leave the Amtrak L.A. maintenance yard for a final public appearance until 2020. Click to enlarge.

(By Fanlon verdoe - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=83235818)



Under the Whyte notation for the classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles. The type was first used by the Northern Pacific Railway, and initially named the Northern Pacific, but railfans and railroad employees have shortened the name since its introduction. It is most-commonly known as a Northern.


A diagram of the 4-8-4 wheel arrangement. Front of locomotive on the left. Click to enlarge.

(Gwernol, Public domain, via Wikimedia Commons)



The 4-8-4 wheel arrangement was a progression from the 4-8-2 Mountain type and, like the 2-8-4 Berkshire and 4-6-4 Hudson types, an example of the "Super Power" concept in steam locomotive design that made use of the larger firebox that could be supported by a four-wheel trailing truck, which allowed greater production of steam. The four-wheel leading truck gave stability at speed and the eight driving wheels gave greater adhesion. The evolution to the 4-8-4 type occurred in the United States of America soon after the Lima Locomotive Works introduced the concept of "Lima Super Power" in 1925, making heavy 2-8-2 and 2-8-4 locomotives. The prototype was built by American Locomotive Company (ALCO) for the Northern Pacific Railway (NP) in 1926, with a very large firebox with a 100-square-foot (9.3 m2) grate, designed to burn low quality lignite coal. The four-wheel trailing truck weighed about 15,000 pounds (6.8 t) more than two-wheel trucks of the time and could carry an additional 55,000 pounds (25 t) of engine weight; the difference of 40,000 pounds (18 t) was available for increased boiler capacity.

The 4-8-4 type arrived when nearly all the important steam locomotive design improvements had already been proven, including Superheaters, mechanical stokers, outside valve gear and the Delta trailing truck. One-piece, cast steel bed-frames with integrally cast cylinders gave the strength and rigidity to use Roller bearings. In 1930, the Timken Company used the Timken 1111, a 4-8-4 built by ALCO with roller bearings on all axles, to demonstrate the value of their sealed roller bearings. The Timken 1111 was subsequently sold to the NP, where it became NP No. 2626, their sole Class A-1 locomotive.

The stability of the 4-8-4 wheel arrangement meant that driving wheels up to 80 inches (2.0 m) diameter could be used for high speed passenger and fast freight operation. Lateral control devices allowed these locomotives to traverse relatively sharp curves despite their eight-coupled drivers. The increased boiler size possible with this type, together with the high axle loads permitted on mainlines in North America, resulted in the design of some massive locomotives, some of which weighed as much as 450 tons, including the tender. The 4-8-4 was suitable for both express passenger and fast freight service, though it was not suited to heavy drag freight trains.

Although locomotives of the 4-8-4 wheel arrangement were used in a number of countries, those that were developed outside North America included various design features which set them apart from North American practice. Scaled down examples of the type were exported by two American builders, ALCO and Baldwin Locomotive Works, for 1,000 mm (3 ft 3+3⁄8 in) meter gauge lines in Brazil.


The Northern name

Since the 4-8-4 was first used by the Northern Pacific Railway, the type was named "Northern". Most North American railroads used this name, but some adopted different names.


Timken 1111, the experimental steam engine built for the Timken Roller Bearing Company by ALCO. Click to enlarge.

(Great Northern Railway, Public domain, via Wikimedia Commons)



The big-wheeled 4-8-4 was at home on heavy passenger trains and quite capable of speeds over 100 miles per hour (160 km per hour), but freight was the primary revenue source of the railroads; in that service the Northern had limitations. The adhesive weight on a 4-8-4 was limited to about 60% of the engine's weight, not including the dead weight of the tender. Henry Bowen, the Chief Mechanical Engineer of the Canadian Pacific Railway (CPR) from 1928 to 1949, tested the first two CPR K-1a Northerns introduced by his predecessor, then he designed a 2-10-4 Selkirk type using the same boiler. The resulting T-1a Selkirk locomotive had the same number of axles as the Northern, but the driving wheels were reduced from 75 to 63 inches (1.9–1.6 m) in diameter, while the additional pair of driving wheels increased the tractive effort by 27%. In a later variant, Bowen added a booster to the trailing truck, enabling the Selkirk to exert nearly 50% more tractive effort than the similar-sized K-1a Northern.

When it was demonstrated that a three-unit EMD F3 diesel-electric consist that weighed slightly less than the total engine and tender mass of a CPR K-1a Northern could produce nearly three times its tractive effort, high-powered steam locomotives were retired as quickly as finance allowed.


Lima-built Southern Pacific 4-8-4 class GS-4 No. 4449. Click to enlarge. (Jerry Gaiser (en:User:Jerryg) https://creativecommons.org/licenses/by-sa/2.5/deed.en via Wikimedia Commons)

Union Pacific 844 is the only steam locomotive never retired by a North American Class I railroad. Shown here at Painted Rocks, NV in 2009. Click to enlarge. (04_15_09_162xp_-_Flickr_-_drewj1946.jpg: Drew Jacksich from San Jose, CA, The Republic of California, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons)


United States

The American 4-8-4 was a heavy locomotive, with nearly all examples in the United States having axle loads of more than 30 short tons (27 tonnes). On railroads with rail of 130 to 133 pounds per yard (64 to 66 kg per meter), axle loads of more than 36 tons (33 tonnes) were permitted. Exceptionally heavy 4-8-4s were therefore introduced on the Atchison, Topeka and Santa Fe (Santa Fe), Chicago and North Western (CNW), Chesapeake and Ohio (C&O), Milwaukee Road (MILW), Northern Pacific (NP), Norfolk and Western (N&W), Spokane, Portland and Seattle (SP&S) and Western Maryland (WM) railroads. The Santa Fe Class 2900 had the heaviest axle load of all at 38.75 tons (35.15 tonnes) as well as being the heaviest 4-8-4s ever built, weighing 974,850 lb (442,180 kg) total. The lightest 4-8-4s in the United States were the six H-10 class locomotives of the Toledo, Peoria and Western (TPW), with an axle load of 23 tons (21 tonnes).

Some 4-8-4s were used on exceptionally long runs.

The Santa Fe Heavy Mountains were rostered to haul the Chief and Fast Mail trains between La Junta, Colorado and Los Angeles across 1,255 miles (2,020 km), and also handled the Grand Canyon Limited between Los Angeles and Wellington, Kansas, across 1,534 miles (2,469 km). From 1942, they ran through from Los Angeles to Kansas City via the Belen Cutoff and Amarillo, Texas, a distance of 1,789 miles (2,879 km), setting a new record for through steam locomotive rosters.
The Niagaras of the New York Central Railroad (NYC) also accomplished long runs on New York to Chicago passenger trains, including the Chicagoan and the Commodore Vanderbilt.
The Northern Pacific 4-8-4s hauled the North Coast Limited across 1,008 miles (1,622 km) from St. Paul, Minnesota, to Livingston, Montana.
The Great Northern S-2 Class of 4-8-4s hauled the Empire Builder across 1,306 miles (2,102 km) from St. Paul, Minnesota to Wenatchee, Washington and possibly as far west to Seattle, a maximum distance of 1,400 miles (2,300 km).
Several of the earlier 4-8-4 locomotive models were modified or rebuilt during their service lives.

Santa Fe developed their 4-8-4s for years, and named the classes based on the number of the first locomotive in the class. The fourteen 3751 class locomotives that were introduced in 1927 and 1928 were of conservative design, with 73 inches (1,854 mm) diameter driving wheels and a boiler pressure of 210 pounds per square inch (1,400 kPa). In 1938, these locomotives were rebuilt with more modern features, including new 80 inches (2,032 mm) diameter Boxpok driving wheels, increased size steam passages to and from the cylinders, the boiler pressure raised to 230 pounds per square inch (1,600 kPa) and roller bearings on all engine axles. This gave them a maximum drawbar power of 3,600 horsepower (2,700 kw) at 50 miles per hour (80 km per hour). Engine no. 3752 was equipped with Franklin rotary cam poppet valve gear and achieved the very low steam rate of 13.5 lb per indicated horsepower-hour (2.28 mg/J). These locomotives were permitted to run at 90 miles per hour (140 km per hour), but they were alleged to have exceeded 100 miles per hour (160 km per hour) several times.
The heavy Class H Northerns of the Chicago and Northwestern Railroad were rebuilt in 1940 with lightweight rods, Boxpok driving wheels and roller bearings on all axles, and the boiler pressure was raised from 250 to 275 pounds per square inch (1,720 to 1,900 kPa). Some years later, 24 of them underwent another rebuild which included new nickel-steel frames, new cylinders, pilot beams and air reservoirs, new fireboxes and other minor improvements. These were reclassified as Class H-1.

The S-2 Class Northerns of the Great Northern Railway were rebuilt to have Timken roller bearings on every axle in 1945, replacing their original plain bearings. Vestibule cabs were added to engine 2577 in the early 1930s and engines 2582, 2586, 2587 and 2588 by the late 1940s.

Some Northern locomotives were also rebuilt from older engines. Between 1945 and 1947, the Reading Railroad rebuilt thirty of their heavy I-10 class 2-8-0 Consolidations to booster-fitted 4-8-4 Northern locomotives with 70 inches (1,778 mm) diameter driving wheels. An additional ring was added at the smokebox end of the boiler, which increased the length of the boiler tubes from 13 feet 6 inches (4.11 m) to 20 feet (6.1 m), and a larger smokebox was installed which increased the distance between the tube plate and the chimney center line from 34 inches (0.86 mm) to 111 inches (2.8 m). Steam pressure was raised from 220 to 240 pounds per square inch (1,500 to 1,700 kPa). Four syphons were fitted, three in the firebox proper and one in the combustion chamber. A twelve-wheeled tender was attached, weighing 167 tons in working order, with a capacity of 23.5 tons of coal and 19,000 US gallons (72,000 liters) of water. A new cast-steel frame was used, with the cylinders cast integral and roller bearings on all axles. They were reclassified to T1 and numbered 2100 to 2129. Two of these locomotives, preserved for hauling special trains, were still in use in 1963.

Southern Pacific class GS-4
The Northerns were workhorses that went without much public recognition, with a few exceptions. The Class GS-4 Golden State locomotives of Southern Pacific (SP), of which 36 were built by Lima Locomotive Works in 1941 and 1942, were semi-streamlined and were given a striking livery with a broad orange valence over the wheels below a narrow red band that came halfway up the cab windows. The locomotives headed the Coast Daylight train on the railroad's Coast Line between Los Angeles and San Francisco. The television program The Adventures of Superman was introduced with a shot of an SP GS-4 as the announcer declared that Superman was "more powerful than a locomotive." One of them, Southern Pacific 4449, has been restored and is in operating condition. Even after the demise of steam, the Northern type has been in the spotlight of publicity and, along with Union Pacific 844 of the Union Pacific FEF Series and Norfolk and Western 611 of the Norfolk and Western Class J series, among other Northerns, have been the favored type to provide mainline excursions in the United States. The former is the only steam locomotive of a Class I railroad never to have been retired.

North American production
Most North American 4-8-4s were built by ALCO, Lima and the Baldwin Locomotive Works, while Canadian National Railway's fleet was built by Montreal Locomotive Works. Only the Canadian Pacific Railway, the Norfolk and Western Railway, the St. Louis Southwestern Railway (Cotton Belt) and the Reading Railroad built or rebuilt their own. The Missouri Pacific rebuilt one class of their 4-8-4s from their class BK-63 2-8-4s.

The Northern type was used by 37 railroads in the Americas, including 31 railroads in the United States, three in Canada, one in Mexico and two in Brazil. In all, there were fewer than 1,200 locomotives of this type in North America, compared to the approximately 2,500 4-8-2 Mountain types and 6,800 4-6-2 Pacific types. By far the largest fleet was owned by the CN and its subsidiary, the Grand Trunk Western Railroad, with altogether 203 locomotives. To see a list of North American produced 4-8-4s, click HERE.


Canadian National Railways U-4-a class 4-8-4 Northern 6400, shown here at the 1939 New York World's Fair.

(Gottscho-Schleisner, Public domain, via Wikimedia Commons)



Since the Canadian mainlines were generally laid with 115-pound-per-yard (57 kg/m) rail, Canadian 4-8-4s were heavy and weighed in with axle loads up to 31.3 short tons (28.4 t).

When the Canadian National Railway (CN) introduced its first 4-8-4 in 1927, it used the name "Confederation" for the type, to celebrate the 60th anniversary of the Canadian Confederation. The CN employed a total of 160 Confederation locomotives.

Altogether forty locomotives were delivered in 1927, twenty Class U-2-a from the Canadian Locomotive Company and twenty Class U-2-b from the Montreal Locomotive Works (MLW).

Another twenty Class U-2-c came from MLW in 1929 and another five Class U-2-d, also from MLW, in 1936.

The CN U-4a was one of the few streamlined Confederation types, with five locomotives built by MLW and also introduced in 1936. U-4a No. 6400 achieved fame in 1939 by heading the Royal Train and being exhibited at the New York World's Fair in the same year.
Between 1940 and 1944, a total of ninety more Confederation locomotives, built in four batches, were added to the CN roster.

The Canadian Pacific Railway (CPR) experimented with the 4-8-4 wheel arrangement in 1928, when two K-1a class locomotives were built in its Angus shops in Montreal, the first locomotives to be built with a one-piece cast-steel frame in Canada. However, since the CPR mainlines were built to high standards, the railway preferred to develop the 4-6-4 Hudson type for passenger work since it gave adequate power and was cheaper to maintain, while a ten-coupled type, the 2-10-4 Selkirk, was adopted for heavy-duty work.

Nevertheless, although the two CPR Northerns remained orphans, they proved their worth continuously for 25 years on overnight passenger trains between Montreal and Toronto. Before their retirement in 1960, they were converted to oil-burners and worked freight trains in the prairie provinces.


NdeM 4-8-4 Niagara No. 3049 working in Valle de Mexico yards, Tlalnepantla, Mexico on September 13, 1966.

See more HERE.

(Photo by Roger Puta via Marty Bernard from U.S.A., Public domain, via Wikimedia Commons)



In 1946, the Ferrocarriles Nacionales de México (N de M) placed orders with American Locomotive Company and Baldwin Locomotive Works for sixty Niágara locomotives for use on its principal express passenger services on upgraded lines, but the order was reduced to 32 in favor of diesel-electric locomotives. These QR-1 class locomotives were used mainly on lines north of Mexico City and were nicknamed La Maquina. All were taken out of service in the late 1960s. Most survived and No. 3028, although not in operating condition, was stored on the deadline at the New Hope and Ivyland Railroad in New Hope, Pennsylvania.


Preserved Units

United States

Atchison, Topeka & Santa Fe 2903: On display at the Illinois Railway Museum in Union, Illinois.
Atchison, Topeka & Santa Fe 2912: On static display in Pueblo, Colorado.
Atchison, Topeka & Santa Fe 2913: On display in Fort Madison, Iowa.
Atchison, Topeka & Santa Fe 2921: On display at the Amtrak Station in Modesto, California.
Atchison, Topeka & Santa Fe 2925: On display at the California State Railroad Museum in Sacramento, California.
Atchison, Topeka & Santa Fe 2926: Currently under restoration for excursion service in Albuquerque at a site leased from the GSA near 8th Street and Haynes Avenue. More information at New Mexico Steam Locomotive and Railroad Historical Society.
Atchison, Topeka & Santa Fe 3751: Restored in 1991, owned by the San Bernardino Railroad Historical Society, and is operated in excursion service. It is the oldest surviving 4-8-4, the first one to be built by the Baldwin Locomotive Works and the first 4-8-4 to be built for the Santa Fe.
Atchison, Topeka & Santa Fe 3759: On Display in Kingman, Arizona.
Atchison, Topeka & Santa Fe 3768: On display at the Great Plains Transportation Museum in Wichita, Kansas.
Chesapeake and Ohio 614: Restored in 1980 and again in 1995, owned by Iron Horse Enterprise, Clifton Forge, Virginia.
Chicago, Burlington and Quincy 5614: On display at Patee Park in St. Joseph, Missouri.
Chicago, Burlington, and Quincy 5629: On display at the Colorado Railroad Museum in Golden, Colorado.
Chicago, Burlington, and Quincy 5631: On display at Rotary Park in Sheridan, Wyoming.
Chicago, Burlington, and Quincy 5633: On display at the Douglas Railroad Interpretive Center, Douglas, Wyoming.
Grand Trunk Western 6323: On display at the Illinois Railway Museum in Union, Illinois.
Great Northern 2584: On display at the Havre depot in Havre, Montana.
Milwaukee Road 261: Restored in 1993, owned, maintained, and operated by the Friends of the 261 in Minneapolis, Minnesota.
Milwaukee Road 265: On display at the Illinois Railway Museum in Union, Illinois.
Nashville, Chattanooga, and St. Louis 576, Nashville, Tennessee - Presently undergoing Restoration.
Norfolk and Western 611: Ran frequent excursions in the 1980s and early 1990s, then placed on static display at the Virginia Museum of Transportation, Roanoke, Virginia. The second restoration to operational condition completed in mid 2015 at the North Carolina Transportation Museum, Spencer, North Carolina.
Reading 2100: Restored in 1988 and 1998, converted to burn oil in the Early 2000s. On long-term lease to the American Steam Railroad. Currently under restoration to operating condition.
Reading 2101: On display at the B&O Railroad Museum in Baltimore, Maryland.
Reading 2102: Reading & Northern Railroad, Port Clinton, Pennsylvania, has been restored to operating condition in April 2022.
Reading 2124: Used on the "Reading Rambles" in the late 1950s and 1960s. On display at Steamtown National Historic Site in Scranton, Pennsylvania.
St. Louis Southwestern No. 819: Built in 1943, it was the last locomotive built by the Cotton Belt and the last Cotton Belt steam locomotive built. Restored to service in 1986 and housed at the Arkansas Railroad Museum in Pine Bluff, Arkansas.
St. Louis-San Francisco 4500: As the Frisco Meteor, ran overnight passenger service between St. Louis, Tulsa and Oklahoma City. Cosmetically restored and relocated in 2011 to the Route 66 Historical Village at 3770 Southwest Blvd in Tulsa, Oklahoma.
St. Louis-San Francisco 4501: Built in 1942, ran overnight passenger service as the Frisco Meteor between St. Louis, Tulsa, and Oklahoma City. Donated to the Dallas Museum of the American Railroad in September 1964.
St. Louis-San Francisco 4516: On display at the Missouri State Fairgrounds in Sedalia, Missouri.
St. Louis-San Francisco 4524: On display at Grant Beach Park in Springfield, Missouri. This was the last steam locomotive built for the Frisco.
Spokane, Portland and Seattle 700: Restored in 1990 by the Oregon Rail Heritage Foundation, and is operated in excursion service. No. 700 is stored at the Oregon Rail Heritage Center in Portland, Oregon, along with SP 4449. It is the only surviving original Spokane, Portland and Seattle railway steam locomotive.
Southern Pacific 4449: Still in operation, served as the locomotive for the Bicentennial American Freedom Train. Stored at the Oregon Rail Heritage Center in Portland, Oregon along with SPS 700.
Southern Pacific 4460: On display at the National Museum of Transportation in St. Louis, Missouri. This was the last steam locomotive used in revenue service by SP. Full Restoration unlikely to happen due to boiler being sandblasted.
Union Pacific 814: On display at the Rock Island Depot Museum in Council Bluffs, Iowa.
Union Pacific 833: On display at the Utah State Railroad Museum in Ogden, Utah.
Union Pacific 838: Union Pacific Railroad, stored in Cheyenne, Wyoming. Used solely as a source of spare parts for sister engine 844.
Union Pacific 844: Formerly Union Pacific 8444 is the last steam locomotive built for Union Pacific Railroad (12/1944). Part of UP heritage fleet, often used for running in excursion service, and on occasion revenue service. Never retired, it is the longest continuously operating steam locomotive on a Class 1 Railroad. Kept at Cheyenne, Wyoming, when not on excursion.


Canadian National 6153: On static display at the Canadian Railway Museum in Delson, Quebec.
Canadian National 6167: On static display in downtown Guelph, Ontario.
Canadian National 6200: Canadian Science & Technology Museum, Ottawa, Ontario.
Canadian National 6213: On static display in downtown Toronto, Ontario, at the Toronto Railway Heritage Centre.
Canadian National 6218: Fort Erie Railroad Museum, Fort Erie, Ontario. Used by the CN on excursions in the 1960s and 1970s.
Canadian National 6400: Canadian Science & Technology Museum, Ottawa, Ontario.
Canadian Pacific 3100: Canadian Science & Technology Museum, Ottawa, Ontario.
Canadian Pacific 3101: On display at EVRAZ (formerly IPSCO Steel), Regina, Saskatchewan.
Grand Trunk Western 6323: On display at the Illinois Railway Museum in Union, Illinois.
Grand Trunk Western 6325: Restored in 2001 by the Ohio Central Railroad, owned by Age of Steam Roundhouse, Sugarcreek, Ohio. Currently, the locomotive needs valve and running gear work.


N de M 3027: Guadalajara, Jalisco.
N de M 3028: Retired in 1966, acquired by the Great North Eastern Railroad Foundation, and displayed at the Altamont, New York, fairgrounds until 1983. On lease to the New Hope and Ivyland Railroad.
N de M 3030: Zacatecas, Zacatecas.
N de M 3031: Huehuetoca, Mexico.
N de M 3033: Pachuca, Hidalgo.
N de M 3034: Puebla, Puebla.
N de M 3035: Aguascalientes, Aguascalientes.
N de M 3036: Leon, Guanajuato.
N de M 3038: Mexico City.
N de M 3039: Monterrey, Nuevo Leon.
N de M 3040: Oriental, Puebla.
N de M 3056: Tequisuiapan, Queretaro.


Spokane, Portland and Seattle No. 700 at Vancouver, WA in 2008.

(Christopher Chen from Portland, Oregon, United States, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons)



Equivalent classifications:
UIC class 2′D2′
French class 242
Turkish class 48
Swiss class 4/8
Russian class 2-4-2
First known tender engine version
First use: 1926
Country: United States
Locomotive: NP class A
Railway: Northern Pacific Railway
Designer: American Locomotive Company
Builder: American Locomotive Company
Evolved from: 4-8-2, 4-6-4
Benefits: Deeper firebox than the 4-8-2.