Editing 2-8-8-4 (section)

==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}}