View source for 2-8-8-4

{{Short description|Articulated locomotive wheel arrangement}}
{{More footnotes|date=May 2010}}
[[Image:Duluth Missabe and Iron Range 2-8-8-4 locomotive.jpg|thumb|Duluth, Missabe & Iron Range 2-8-8-4 "Yellowstone" No. 229, as preserved in 1987]]
A '''2-8-8-4''' steam locomotive, under the [[Whyte notation]], has two [[leading wheel]]s, two sets of eight [[driving wheel]]s, and a four-wheel [[trailing truck]]. The type was generally named the ''Yellowstone'', a name given it by the first owner, the [[Northern Pacific Railway]], whose lines ran near [[Yellowstone National Park]]. Seventy-two Yellowstone-type locomotives were built for four U.S. railroads.

Other equivalent classifications are:
*[[UIC classification]]: '''1DD2''' (also known as [[UIC classification of locomotive axle arrangements|German classification]] and [[Italian classification]])
*[[French classification]]: '''140+042'''
*[[Turkish classification]]: '''45+46'''
*[[Swiss classification]]: '''4/5+4/6'''
*[[:ru:Осевая формула паровоза#Русский|Russian classification]]: '''1-4-0+0-4-2'''

The equivalent UIC classification is, refined for simple articulated locomotives, '''(1′D)D2′'''.

A locomotive of this length must be an [[articulated locomotive]]. All Yellowstones had fairly small drivers of {{Convert|63|to|64|in|m|sigfig=3}}. (For greater speeds, the [[Union Pacific Railroad]] chose a four-wheel leading truck and drivers of {{Convert|68|in|m|sigfig=3}} for its [[Union Pacific Big Boy|Big Boy]] 4-8-8-4 class.)

Several classes of Yellowstone, especially the [[Duluth, Missabe and Iron Range]]'s locomotives, are among the largest steam locomotives, with the exact ranking depending on the criteria used.

==Northern Pacific==
The [[Northern Pacific Railway]] was the first railroad to order a 2-8-8-4. The first was built in 1928 by [[American Locomotive Company]]; at the time, it was the largest locomotive ever built. It had the largest [[Firebox (steam engine)|firebox]] ever applied to a steam locomotive, some {{Convert|182|ft2|m2}} in area, to burn Rosebud coal, a cheap low-quality coal. But the firebed was too large for the available draft and the fire burned poorly and developed under 5,000 horsepower. The problem was mitigated by blocking off the first few feet of the grates. [[Baldwin Locomotive Works]] built 11 more for the Northern Pacific in 1930. No examples have been preserved.

==Southern Pacific==
The [[Southern Pacific Railroad|Southern Pacific Railroad's]] famous "[[cab forward]]" articulated steam locomotives were effectively a Yellowstone in reverse ([[4-8-8-2]]). This was done to spare the crew from the heavy smoke output of the large engines on the former Central Pacific, where tunnels and snow sheds were common and lengthy. [[Southern Pacific 4294|One is on display]] at the [[California State Railroad Museum]] in Sacramento. The ready availability of fuel oil in California made them possible. The SP also owned some conventional 2-8-8-4s for use in areas where coal was plentiful and snow sheds were rare. [[Lima Locomotive Works]] built 12 [[Southern Pacific class AC-9|AC-9 class locomotives]] in 1939; they had skyline casings with striped [[pilot (locomotive attachment)|pilot]]s. At first, they burned coal but were later converted to oil. None were saved.

==Duluth, Missabe and Iron Range==
{{Infobox locomotive
|image           = DM&IR Mallet Engine 227- 2-8-8-4 Yellowstone, Baldwin, 1941.jpg
|caption         = DM&IR 227 at the Lake Superior Railroad Museum.
|name            = DM&IR Yellowstones
|powertype       = Steam
|builder         = [[Baldwin Locomotive Works]]
|builddate       = 1941 (8) 1943 (10)
|totalproduction = 18
|whytetype       = 2-8-8-4
|uicclass        = (1′D)D2′
|gauge           = {{RailGauge|ussg}} [[standard gauge]]
|leadingdiameter = 
|driverdiameter  = {{Convert|63|in|mm|0|abbr=on}}
|trailingdiameter= 
|wheelbase       = {{Convert|113.49|ft|6.7|in|m|2|abbr=on}}
|length          = 
|width           = 
|height          = 
|axleload        = {{convert|70032|lb|kg t|abbr=in|sp=us}}
|weightondrivers = {{Convert|560257|lb|kg t|abbr=on}}
|locoweight      = {{Convert|695040|lb|kg t|abbr=on}}
|tenderweight    = {{Convert|438000|lb|kg t|abbr=on}}
|locotenderweight= {{Convert|1133040|lb|kg t|abbr=on}}
|fueltype        = [[Coal]]
|fuelcap         = {{Convert|26|ST|t LT}} 
|watercap        = {{Convert|25000|USgal|m3|abbr=on}}
|consumption     = {{convert|10|t|abbr=on}} to {{convert|12|t|abbr=on}} of coal per hour<br/>{{convert|12000|usgal|abbr=on}} of water per hour
|boiler          = {{Convert|108|in|mm|0|abbr=on}}
|boilerpressure  = {{Convert|240|psi|MPa|abbr=on}}
| firearea  = {{Convert|125|sqft|m2|abbr=on}}
| fireboxarea  = 
| superheatertype  = 
| feedwaterheater = 
|cylindercount   = Four
|cylindersize    = {{Convert|26|by|32|in|mm|0|abbr=on}}
|maxspeed        = {{convert|45|mph|abbr=on}} (limited with ore trains)
|poweroutput     = {{convert|6250|hp|abbr=on}} @ about 40 mph
|tractiveeffort  = {{Convert|140093|lbf|kN|abbr=on}}
|factorofadhesion  = 4.00
|operator        = [[Duluth, Missabe & Iron Range Railway]] (DM&IR)
|operatorclass   = M-3, M-4
|fleetnumbers = ''220–237''
|retiredate      = 1958-1963
|preservedunits  = 3 (225, 227 & 229)
|disposition     = Three preserved and on display, remainder scrapped.
}}
The [[Duluth, Missabe and Iron Range Railway]] hauled iron ore in [[Minnesota]]. Iron ore is heavy and the DM&IR operated long trains of ore cars, requiring maximum power. These locomotives were based upon ten [[2-8-8-2]]s that Baldwin had built in the 1930s for the [[Western Pacific Railroad]]. The need for a larger, coal-burning firebox and a longer, all-weather cab led to the use of a four-wheel trailing truck, giving them the "Yellowstone" wheel arrangement. They were the most powerful Yellowstones built, producing {{Convert|140000|lbf|kN|abbr=on}} of [[tractive effort]], and had the most weight on drivers so that they were less prone to slipping.

Eight locomotives (class M-3) were built by Baldwin in 1941. The Yellowstones met or exceeded the DM&IR specifications, so 10 more were ordered (class M-4). The second batch was completed in late 1943 after the Missabe's seasonal downturn in ore traffic, so some of the new M-4s were leased to and delivered directly to the [[Denver and Rio Grande Western Railroad]].

The next winter, the D&RGW again leased the DM&IR's Yellowstones as [[Bank engine|helpers]] over [[Tennessee Pass (Colorado)|Tennessee Pass, Colorado]], and for other freight duties. The Rio Grande returned the Yellowstones after air-brake failure caused No. 224 to wreck on the Fireclay Loop.{{sfn|LeMassena|2000}}{{page needed|date=February 2017}} This was despite the Rio Grande's earlier assessment that these Yellowstones were the finest engines ever to operate there.

DM&IRs were the only Yellowstones to have a high-capacity pedestal or [[centipede tender]], and had [[roller bearing]]s on all axles. Some of the locomotives had a cylindrical Elesco [[feedwater heater]] ahead of the [[chimney|smoke stack]], while others had a Worthington unit with its rectangular box in the same location.

Only one Yellowstone was retired before [[dieselization]] took place on the Missabe; No. 237 was sold for scrap after a wreck. The rest of the 2-8-8-4s were retired between 1958 and 1963 as diesel locomotives took over.

Of the eighteen built, three survive and are on display in Minnesota: No. 225 at [[Proctor, Minnesota|Proctor]], No. 227 at the [[Lake Superior Railroad Museum]] in [[Duluth, Minnesota|Duluth]] and No. 229 at [[Two Harbors, Minnesota|Two Harbors]].
{{Clear}}

==Baltimore and Ohio==
{{Infobox locomotive
| name = B&O EM-1 2-8-8-4 Yellowstone
| image = Baltimore and Ohio Railroad (B&O) No. 7600, Class EM-1, 2-8-8-4 (Yellowstone).tif
| caption = 
| powertype = Steam
| builder = [[Baldwin Locomotive Works]]
| builddate = 1944 (20) 1945 (10)
| totalproduction = 30
| whytetype = 2-8-8-4
| uicclass = (1′D)D2′
| gauge = {{RailGauge|ussg}} [[standard gauge]]
| leadingdiameter = {{Convert|30|in|mm|0|abbr=on}}
| driverdiameter = {{Convert|64|in|mm|0|abbr=on}}
| trailingdiameter = {{Convert|38|in|mm|0|abbr=on}}
| wheelbase = {{Convert|81|ft|6.7|in|m|2|abbr=on}}
| length = Locomotive: {{Convert|83|ft|2.9|in|m|2|abbr=on}}<br />Overall: {{Convert|128|ft|8|in|m|2|abbr=on}}
| width = {{Convert|11|ft|m|3|abbr=on}}
| height = {{Convert|16|ft|m|3|abbr=on}}
| weightondrivers = {{Convert|485000|lb|kg t|abbr=on}}
| locoweight = {{Convert|627000|lb|kg t|abbr=on}}
| tenderweight = {{Convert|328000|lb|kg t|abbr=on}}
| locotenderweight = {{Convert|1010700|lb|kg t|abbr=on}}
| fueltype = [[Coal]]
| fuelcap = {{Convert|25|ST|t LT}}
| watercap = {{Convert|22000|USgal|m3|abbr=on}}
| boiler = {{Convert|100|in|m|2|abbr=on}} dia.
| boilerpressure = {{Convert|235|psi|MPa|abbr=on}}
| firearea = {{Convert|117.5|sqft|m2|abbr=on}}
| fireboxarea = {{Convert|228|by|96|in|m|2|abbr=on}} with a {{Convert|90|in|m|2|abbr=on|adj=on}} long combustion chamber
| superheatertype = Type "E"
| feedwaterheater = Worthington
| cylindercount = Four
| cylindersize = {{Convert|24|by|32|in|mm|0|abbr=on}}
| poweroutput = {{convert|6000|hp|abbr=on}}
| tractiveeffort = {{Convert|115000|lbf|kN|abbr=on}}
| factorofadhesion = 4.22
| operator = [[Baltimore and Ohio Railroad]] (B&O)
| operatorclass = EM-1
| fleetnumbers = ''7600–7629'' later ''650–679''
| lastrundate = April 19, 1960
| disposition = All thirty scrapped by 1961
}}
When the U.S. entered World War II The American railroads saw increases in traffic. The [[Baltimore and Ohio Railroad]], along with other railroads, wanted to purchase more [[diesel locomotive|diesel]], as the technology was rapidly improving to the point that it would soon surpass steam locomotives. But the War Production Board regulated the production of steam and diesel locomotives until the war emergency was over. So, alongside the production of 40 new class T-3 4-8-2 type locomotives built at the railroad's own Mt. Clare shops, the B&O ordered 30 [[Baltimore and Ohio Railroad locomotives|class EM-1]] Yellowstones from Baldwin in 1944 and 1945, becoming the smallest, most numerous, and most modern of this type.

The EM-1 produced {{convert|115000|lbf|kN}} of tractive effort on {{convert|64|in|m|adj=on}} drivers with {{convert|235|psi|MPa}} steam pressure and four {{convert|24|by|32|in|m|adj=on}} cylinders.  The tender carried {{convert|22000|USgal|m3}} of water and 25 tons of coal. The engine weighed {{convert|627000|lb|t}} while the tender weighed {{convert|328000|lb|t}} for a combined {{convert|1010700|lb|t}}. Nothing bigger could operate within the tunnel clearances and track restrictions on the B&O's main line.

They were equipped with the newest technology of the time. They featured the Worthington feedwater heater, superheater with front-end throttle, Cyclone front end, thermic syphons, a lateral cushioning device in the front pair of drivers on both engines and the front wheels and the trailing truck, and roller bearings on all axles, engine and tender. The latter gave them the reputation of "yard creepers", because three men could move one on a level track with the cylinder cocks open.

B&O's president, Roy B. White, after inspecting the first one delivered, said to the general superintendent of motive power and equipment, A.K. Galloway, "Well, I must say, they have everything!"

Fleet numbers 7600–7619 were built and delivered in 1944 and 7620–7629 in 1945, all by the Baldwin Locomotive Works of Philadelphia, Pennsylvania. They went to work on the Cumberland Division's rugged West End subdivision with its more than 2% grades and tight curves, where they supplemented older 2-8-8-0 EL classes on West Virginia coal and freights. Since the EM-1s had roller bearings throughout, they handled mail and express trains too, replacing two T-3s in this role. In January 21, 1947, when, near Oakland, Maryland, train 29 with engine 7625 derailed with the locomotive rolling onto the engineer's side, killing the engineer. After this accident, the EM-1s were restricted to coal and freight trains in regular service for the rest of their working lives. However, the B&O would use EM-1 No. 7600 for railfan trips in the late 1950s.{{sfn|Roberts|2001}}{{page needed|date=February 2017}}

The EM-1s also ran on the Pittsburgh Division over Sand Patch Grade near Meyersdale, Pennsylvania. While they mainly hauled general freight workings here, they were best known for pulling loads of iron ore or dolomite westbound, or coal eastbound. In the late 1950s, the B&O used EM-1 No. 7600 for railfan trips mostly between Cumberland, MD, and Connellsville, PA. Well-known photographer and Cumberland, MD native William P. Price captured, on still pictures and 8mm films, the EM-1s on the east side of Sand Patch pulling heavy trains with two of the B&O's 2-10-2 class S1 and S1a Big Sixes on the rear as helpers dispatched from Hyndman, PA. 
 
Near the end of steam they were all sent out to Fairmont and Wheeling, West Virginia, and Lorain, Ohio, with lake-bound coal trains as well as runs between Willard, OH and Garrett, Indiana, until the B&O retired them from 1957. Two engines, 650 (7600) and 659 (7609), were subjects of preservation attempts, but neither succeeded. No. 650 (7600) was earmarked for preservation by the [[B&O Railroad Museum]] in [[Baltimore]], but a yard master mistakenly interpreted the order for the engine's move to the museum as one for the engine to be taken to the scrapyard. No. 650 was broken up, and the yard master was fired soon after. No. 659 (7609) was offered to the city of [[Wheeling, West Virginia|Wheeling]], [[West Virginia]] for static display. The city turned down the offer, and the engine was scrapped soon after. Thus, none of the EM-1s survive today.

==Outside the United States==

The [[Metre-gauge railway|metre-gauge]] [[Estrada de Ferro Central do Brasil|Central Railway of Brazil]] took delivery of four 2-8-8-4s from the [[Germany|German]] firm of [[Henschel]] in 1937. They were the only narrow gauge locomotives of this [[wheel arrangement]]. They had the largest boilers ever used on a narrow-gauge simple expansion locomotive.
[[File:Parovoz 38 razmeri.jpg|thumb|Class P38 locomotive elevation]]
Soviet Russia constructed two 2-8-8-4 locomotives at the [[Kolomna Locomotive Works]]. These were the [[:ru:П38|P38]] Class numbers P38.001 and P38.002. The first locomotive carried partial casings over the boiler and smokebox typical of the 1950s. P38.002 bore no such adornments and had a more conventional appearance. Both engines had tenders with part bogie and part fixed frame similar to the American 'centipede' tenders.{{sfn|Rakov|1995}}{{page needed|date=February 2017}}

==Notes==
{{Reflist}}
{{Refbegin}}
* {{cite web| last=Barris| first=W.| title=The Yellowstone Type Locomotive| access-date=January 4, 2003| url=http://www.steamlocomotive.com/yellowstone/| website=SteamLocomotive.com| archive-url=https://web.archive.org/web/20030203053537/http://www.steamlocomotive.com/yellowstone/| archive-date=2003-02-03| url-status=dead}}
* {{cite book| last=Brown| first=John K.| title=The Baldwin Locomotive Works - A Study in American Industrial Practice| publisher=Johns Hopkins University Press| year=1995}}
* {{cite book| last1=Dixon| first1=Thomas W. Jr.| last2=Withers| first2=Bob| title=Baltimore and Ohio's Magnificent 2-8-8-4 EM-1 Articulated Locomotive| year=2007| publisher=TLC Publishing| location=Forest, VA| isbn=978-0-939487-83-7}}
* {{cite journal| last=LeMassena| first=R.| date=2000| title=David Moffat's Double Dilemma| journal=The Railway & Locomotive Historical Society Newsletter| volume=20| issue=2| location=Sacramento| publisher=Railway & Locomotive Historical Society}}
* {{cite book| last=Rakov| first=V.A.| title=Locomotives of the Russian and Soviet Railways - Vol 1 - 1845 to 1955| location=Moscow| publisher = M. Transjeldorizdat | year=1995}}
* {{cite book| last=Roberts| first=Charles S.| title=West End, Cumberland to Grafton 1848–1991| location=Baltimore, MD| publisher=Barnard, Roberts & Co. Inc.| edition=Second| year=2001| isbn=0-934118-18-3}}
* {{cite book| last1=Sagle| first1=Larry| last2=Stauffer| first2=Alvin| title=B&O Power, Steam, Diesel and Electric Power on the Baltimore and Ohio Railroad| edition=Eighth printing| year=1984| lccn=64023526}}
* {{cite book| editor-last=Westcott| editor-first=L.| year=1960| title=Model Railroader Cyclopedia Volume 1: Steam Locomotives| location=Milwaukee, WI| publisher=Kalmbach| oclc=19985835}}
{{Refend}}

==External links==
* [http://www.toytrains1.com/yellowstone.htm Web Site of ToyTrains1 2-8-8-4 Yellowstone Steam Locomotives]
* [https://books.google.com/books?id=T-QDAAAAMBAJ&dq=Popular+Science+1930+plane+%22Popular+Mechanics%22&pg=-PA96 "Is This Monster Locomotive a HE or SHE?" ''Popular Mechanics Monthly'', July 1930]

{{Whyte types}}
{{Rolling stock of Russia}}
{{Authority control}}

[[Category:2-8-8-4 locomotives| ]]
[[Category:Whyte notation|88,2-8-8-4]]
[[Category:simple articulated locomotives]]