Montana Union / Northern Pacific / Oregon & Washington Territory / Seattle & International 2-8-0 "Consolidation" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class F (Locobase 827)

Data from Baldwin Locomotive Works Specification for Engines, as digitized by the DeGolyer Library of Southern Methodist University Volume 12, p. 2. Works numbers were 6591 in January 1883; 6594 in February; 6744 in May; 6796, 6817-6818 in June; and 6988, 7000, and 7002 in October.

With drivers as small as these, it's not really surprising that this class was later converted to G-class 0-8-0s.


Class F-1 (Locobase 829)

Data from DeGolyer, Volume 14, p. 220 and Volume 15,pp. 103 and 148. See also John K Brown, The Baldwin Locomotive Works, 1831-1915: A Study in American Industrial Practice (Baltimore: Johns Hopkins University Press, 1995), pp. 78-80. Works numbers were 9505-9508, 9511, 9514-9516, 9518, 9520, 9524 in August 1888; 9526, 9529 in October; 10000 in May 1889; 10440-10441, 10444-10448, 11305-11306, 11320, 11847, 11914, 11916, 11920, 11948 in November.

John Brown cites this class as an example of Baldwin's ability to take a new design used by one railroad and adapt it to another, often with mutually beneficial results. As noted in Locobase 9424, G W Cushing, new manager of the Reading, ordered this class in 1888. The design broke precedent on the Reading both for its size and for the use of conventional layout. The boiler in particular was quite large for the time. Brown reports (p. 78):

"Baldwin built the custom order and then sold thirteen more engines of Cushing's original design to the Northern Pacific. Here a western line, completed only six years earlier, took advantage of the technical expertise of the fifty-year-old Philadelphia & Reading."

Brown's chronology, as presented on p 78 and on the caption of Locomotive 10000 on p 80 skips the first set of thirteen, which were ordered in June 1888. His point stands, however, as that order came after Cushing's earlier request. In the caption, Brown also supplies the useful addendum that the order included the Westinghouse air brake, Eames vacuum brake, and Westinghouse's train signal.

Three (50-52) were converted to Vauclain compounds for three years (1899-1902), then converted back to simple-expansion engines. As compounds, they had 15 x 28 HP cylinders, 25 x 28 LP cylinders.

Seven were sold in November 1925 to the Spokane, Portland & Seattle as their N-4 class and number 300-305, 315.


Class F-2 (Locobase 830)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004). See also Baldwin Locomotive Works Specification for Engines, 1888, as digitized by the DeGolyer Library of Southern Methodist University Vol 14, 204. Works numbers were 9614 and 9625 in November 1888.

These Consolidations went to the Washington & Columbia River when that railroad bought the O & WT in November 1892. The W & CR folded into the Northern Pacific in July 1907 and these locomotives were renumbered 498-499, then 100-101, and finally 82-83. 82 was rebuilt as an 0-8-0 switcher while 83 was scrapped in July 1928.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class F-3 (Locobase 832)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004).

NY Loco builder information from JF Webber's compilation as supplied by Allen Stanley in March 2004. The first of MU's class of Consolidations was works #455 (February 1889). Six months later the rest of the class rolled out of the Rome shops as works #498-503.

Once the Northern Pacific took over, these 2-8-0s were renumbered frequently, many 3 times over. One - works #501 - was operated by the Seattle & International as their #10, then served with the Northern Pacific, and finally on the Frisco (St Louis-San Francisco).

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class F-4 (Locobase 828)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004). The diagram notes that #94 had 19 1/2" cylinders. Works numbers were 1714-1716 in 1887.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class F-5 (Locobase 837)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004) and supplemented by NP to 1944 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Boiler pressure later increased to 165 psi.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class F-6 (Locobase 834)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004), later http://research.nprha.org/Lists/Class%20List/DispForm.aspx?ID=56. (Thanks to Chris Hohl for his 27 July 2015 email supplying the missing boiler pressure (a Locobase oversight of many years standing) and a typo correction of tender water capacity.)

This single Consolidation was converted to an 0-8-0 switcher in 1912.


Class F-7 (Locobase 831)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004). This is an unusual design with longer tubes.


Class F-8 (Locobase 833)

Data from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

This is an ex-Pennsylvania Railroad locomotive class.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class Y (Locobase 835)

Data from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 4900-4906, 4913-4919 in 1898.

Delivered as compounds in 1898, all of the class was rebuilt and superheated in 1917 (at a total cost of $3,384.55 for each engine) to the dimensions shown. Firebox heating surface area included 15 sq ft (1.39 sq m).


Class Y-1 (Locobase 6559)

Data from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

These were Alco's first tandem-compound locomotives. Each side's HP and LP cylinders were cast as a single unit with the HP cylinder immediately ahead of the larger LP cylinder. The piston valve used for HP steam used internal admission while its LP counterpart used external admission. They had the same diameter and like the pistons below shared the same rod.

The long stroke meant that the LP volume could never be large enough to make full use of the HP exhaust.

Simpled and superheated in 1917; see Locobase 833.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class Y-1 - superheated (Locobase 836)

Data from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Delivered as compounds in 1900, rebuilt 1917 to the dimensions shown. Very similar to the Y-class rebuilds with slightly longer tubes but the same superheater.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class Y-2 (Locobase 838)

Data from "Schenectady Four-Cylinder Tandem Compound Locomotives for the Northern Pacific", Railroad Gazette, VolumeXXXIII [33], No 35 (30 August 1901), pp. 598-599. Schenectady's works numbers were 5881-5892 in 1901. (Thanks to Don Black for his 22 March 2019 email noting the two builders for this class.) Richmond, now part of American Locomotive Company, which was formed in late 1901, supplied the rest as works numbers 25815-25832 in July 1902.

These followed the Y-1s described in Locobase 6559. A big difference was the provision of taller drivers and the use of fewer, but longer boiler tubes. Virtually identical Y-3s with smaller drivers appear in Locobase 839.

Another was the adoption of a tandem compound power system in which the two cylinders on each side laid out with the smaller, high-pressure cylinder in front, the larger, low-pressure cylinder immediately behind. A single piston valve rested on the cylinders and served each in turn. In the production units, the engine saddle was a single unit, but only the LP cylinders and valve chambers were cast integrally with their half saddles. The HP cylinders and valves were cast separately and bolted to the fronts of the LP cylinders.

The first of the class, road number 17, used piston valves on the HP cylinders, slide valves on the LP cans. Superintendent of motive power Alfred Lovell tested the 17 and ordered twelve of this class and fourteen more Y-3s. Both valves per side were 12" (305 mm) pistons.

"The synopsis ...of these parts", said the RG report, "is that, taking the engine saddle as the base of support for steam-acting parts, the high-pressure cylinders and valve. chambers stand as extensioins of the low-pressure parts and with the continuous piston rods and valve rods give a very simple and direct forecast [sic] of operation." RG noted that Schenectady devoted a good deal of effort to simplifying both HP and LP cylinder maintenance

Firebox heating surface area included 26 sq ft (2.42 sq m) in four 3" (76.2 mm) arch tubes.

The NP took its time converting these engines to simple expansion. See Locobase 16420 for the result.

The 1251, 1255, 1260-1261 were not converted, but instead were sold to the Spokane, Portland & Seattle as N-6 class engines. 1255 and 1260 were sold in June 1925 and took road numbers 325-326 and the 1251 and 1261 in October 1936 with road numbers 327-328. They were withdrawn and scrapped in the late 1940s.

The 1257 remained a compound until it was cut up on September 1933.


Class Y-2 - superheated (Locobase 16420)

Data from Northern Pacific Locomotive Data Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. (Many thanks to Don Black for his 22 March 2019 email noting the absence of an entry on this superheated upgrade.)

As noted in Locobase 838, the NP took longer than most North American railroads to remove the balanced compound power system in favor of two simple-expansion cylinders.

According to the data card, the NP simpled the Y-2s at the same time they added a superheater. (The card recorded the cost for the 1250's fitment: $1,635.78; total cost of the update was about $2,500.) The new cylinders had a four-inch (102 mm) shorter stroke. The firebox was unchanged, with four 3" (76.2 mm) arch tubes that contributing 26 sq ft (2.42 sq m) to the firebox heating surface total.


Class Y-3 (Locobase 839)

Data from Data from "Schenectady Four-Cylinder Tandem Compound Locomotives for the Northern Pacific", Railroad Gazette, VolumeXXXIII [33], No 35 (30 August 1901), pp. 598-599. Works numbers were 5893-5906 in 1901.

Four-cylinder tandem compounds built for low-speed drag freight that were substantially larger than the Y-2s delivered at the same time (Locobase 838). Firebox heating surface included 28 sq ft of arch tubes.

Apparently the low-drivered Y-3s did not benefit as much from the tandem compound setup as the NP began simpling and superheating the class in 1914.


Class Y-3 - superheated (Locobase 16421)

Data from Northern Pacific Locomotive Data Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection.

When the NP chose to convert the Y-3 tandem compound drag-freight Consolidations to simple-expansion, the shops modified all fourteen in July 1914. (The locomotive cards show a price of $1,215 for the Schmidt superheater.) Compared to the Y-2 upgrades applied several years later (Locobase 16420), the changes were limited to the superheater conversion and low-pressure cylinder removal.


Class Y-4 (Locobase 840)

Data from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Somewhat smaller than the earlier Y classes, but fitted with much taller drivers.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class Y-4 (Locobase 10272)

4-cylinder tandem compounds built for low-speed drag freight. As such they differed from the Y-2s delivered at the same time, according to RG 30 August 1901. Additional data from AERJ June 1903. Firebox heating surface included 28 sq ft of arch tubes.

These were soon converted to 2-cylinder simple locomotives.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.


Class Y-5 (Locobase 841)

Data from NP 1 -1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley.

The last of the Y series of Consolidations, this set was delivered with two simple-expansion cylinders.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface from the baldwin_steam site.


Class Y-5 (Locobase 10273)

Data from NP Locomotive Cards pdf supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. Works numbers were 27337-27346 in May 1903.

Firebox heating surface area included 24 sq ft (2.23 sq m) of arch tubes, most likely added in a later refit.

1217 was first to leave the roster, being bought by Minnesota Transfer in February 1927 as their #20; it ws scrapped in September 1937. 1216 and 1223 were sold in February 1928 to the Chicago, Springfield & Saint Louis. The 1216 was retired the next year, but 1223 remained on the roster until January 1941, which marked the closing of the CS&StL.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassFF-1F-2F-3F-4
Locobase ID827 829 830 832 828
RailroadNorthern Pacific (NP)Northern Pacific (NP)Oregon & Washington Territory (NP)Montana Union (NP)Montana Union (NP)
CountryUSAUSAUSAUSAUSA
Whyte2-8-02-8-02-8-02-8-02-8-0
Number in Class932283
Road Numbers461-469 / 95-103470-492, 460, 493-497, 650-452/50-817-8 / 498-499 / 100-101 / 82-83154 / 84-91151-152/135-137/110-112/92-94
GaugeStdStdStdStdStd
Number Built932283
BuilderBurnham, Parry, Williams & CoBurnham, Parry, Williams & CoBurnham, Parry, Williams & CoNew York (Rome)Grant
Year18831888188818891887
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)14 / 4.2714 / 4.2714.25 / 4.3415.58 / 4.7514.75 / 4.50
Engine Wheelbase (ft / m)21.50 / 6.5522.17 / 6.7622.33 / 6.8123.17 / 7.0622.75 / 6.93
Ratio of driving wheelbase to overall engine wheebase 0.65 0.63 0.64 0.67 0.65
Overall Wheelbase (engine & tender) (ft / m)49.17 / 14.9949.75 / 15.1648.79 / 14.8747.25 / 14.40
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)96,000 / 43,545135,000 / 61,235122,000 / 55,338113,000 / 51,256100,000 / 45,359
Engine Weight (lbs / kg)108,000 / 48,988150,000 / 68,039136,000 / 61,689125,000 / 56,699113,500 / 51,483
Tender Loaded Weight (lbs / kg)77,500 / 35,15377,600 / 35,19990,000 / 40,82390,000 / 40,823
Total Engine and Tender Weight (lbs / kg)185,500 / 84,141227,600 / 103,238226,000 / 102,512215,000 / 97,522
Tender Water Capacity (gals / ML)3500 / 13.263500 / 13.264244 / 16.082900 / 10.983250 / 12.31
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)7 / 6.407 / 6.409 / 8.206 / 5.506 / 5.50
Minimum weight of rail (calculated) (lb/yd / kg/m)40 / 2056 / 2851 / 25.5047 / 23.5042 / 21
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)49 / 124550 / 127051 / 129551 / 129551 / 1295
Boiler Pressure (psi / kPa)130 / 9150 / 10.30150 / 10.30150 / 10.30140 / 9.70
High Pressure Cylinders (dia x stroke) (in / mm)20" x 24" / 508x61022" x 28" / 559x71121" x 26" / 533x66020" x 24" / 508x61020" x 24" / 508x610
Tractive Effort (lbs / kg)21,649 / 9819.8334,558 / 15675.2628,665 / 13002.2424,000 / 10886.2322,400 / 10160.48
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.43 3.91 4.26 4.71 4.46
Heating Ability
Firebox Area (sq ft / m2)185 / 16.26163 / 15.15148 / 13.75241 / 22.40
Grate Area (sq ft / m2)30.70 / 2.8535.29 / 3.2832.70 / 3.0426.60 / 2.4728 / 2.60
Evaporative Heating Surface (sq ft / m2)2340 / 215.711986 / 184.571868 / 173.612000 / 185.87
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2340 / 215.711986 / 184.571868 / 173.612000 / 185.87
Evaporative Heating Surface/Cylinder Volume189.95190.54214.06229.18
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation39915294490539903920
Same as above plus superheater percentage39915294490539903920
Same as above but substitute firebox area for grate area27,75024,45022,20033,740
Power L13313342638104370
Power MT216.41247.64297.33385.37

Principal Dimensions by Steve Llanso of Sweat House Media
ClassF-5F-6F-7F-8Y
Locobase ID837 834 831 833 835
RailroadSeattle & International (NP)Seattle & International (NP)Seattle & International (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSAUSA
Whyte2-8-02-8-02-8-02-8-02-8-0
Number in Class212614
Road Numbers45-468/4748-49(4-6)30-43
GaugeStdStdStdStdStd
Number Built2126
BuilderSchenectadyRichmondRhode IslandJuniataNP
Year19001895188818911898
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)14 / 4.2714 / 4.2716.08 / 4.9013.67 / 4.1714.67 / 4.47
Engine Wheelbase (ft / m)21.33 / 6.5021.61 / 6.5923.37 / 7.1221.17 / 6.4523.25 / 7.09
Ratio of driving wheelbase to overall engine wheebase 0.66 0.65 0.69 0.65 0.63
Overall Wheelbase (engine & tender) (ft / m)49.12 / 14.9746.41 / 14.1546.42 / 14.15
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)120,250 / 54,545112,000 / 50,802109,000 / 49,44285,300 / 38,691173,300 / 78,608
Engine Weight (lbs / kg)135,000 / 61,235128,000 / 58,060124,000 / 56,24697,600 / 44,271191,000 / 86,636
Tender Loaded Weight (lbs / kg)90,200 / 40,91493,000 / 42,18471,500 / 32,43230,270 / 13,730112,000 / 50,802
Total Engine and Tender Weight (lbs / kg)225,200 / 102,149221,000 / 100,244195,500 / 88,678127,870 / 58,001303,000 / 137,438
Tender Water Capacity (gals / ML)4350 / 16.483835 / 14.533500 / 13.263090 / 11.705500 / 20.83
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)11 / 108 / 7.308 / 7.3010 / 9.1010 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)50 / 2547 / 23.5045 / 22.5036 / 1872 / 36
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)51 / 129551 / 129555 / 139751 / 129555 / 1397
Boiler Pressure (psi / kPa)150 / 10.30150 / 10.30150 / 10.30140 / 9.70200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 24" / 508x61020" x 24" / 508x61020" x 24" / 508x61020" x 24" / 508x61020" x 34" / 508x864
Tractive Effort (lbs / kg)24,000 / 10886.2324,000 / 10886.2322,255 / 10094.7122,400 / 10160.4842,036 / 19067.23
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.01 4.67 4.90 3.81 4.12
Heating Ability
Firebox Area (sq ft / m2)197 / 18.31167164.50 / 15.29228 / 19.24
Grate Area (sq ft / m2)31 / 2.8830 / 2.7926 / 2.4224.90 / 2.3135 / 3.25
Evaporative Heating Surface (sq ft / m2)1984 / 184.391828 / 169.831284 / 119.332151 / 200.84
Superheating Surface (sq ft / m2)468 / 43.49
Combined Heating Surface (sq ft / m2)1984 / 184.391828 / 169.831284 / 119.332619 / 244.33
Evaporative Heating Surface/Cylinder Volume227.35209.47147.14173.99
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation46504500390034867000
Same as above plus superheater percentage46504500390034868260
Same as above but substitute firebox area for grate area29,55025,05023,03053,808
Power L143383891287311,127
Power MT318.13306.36297.02566.20

Principal Dimensions by Steve Llanso of Sweat House Media
ClassY-1Y-1 - superheatedY-2Y-2 - superheatedY-3
Locobase ID6559 836 838 16,420 839
RailroadNorthern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSAUSA
Whyte2-8-02-8-02-8-02-8-02-8-0
Number in Class1313303014
Road Numbers17-2917-291250-12791250-12791200-1213
GaugeStdStdStdStdStd
Number Built13302614
BuilderAlco-SchenectadyAlco-SchenectadySchenectadyNPSchenectady
Year19001917190119181901
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.5715 / 4.5717 / 5.1817 / 5.1815 / 4.57
Engine Wheelbase (ft / m)23.58 / 7.1923.58 / 7.1926.17 / 7.9826.17 / 7.9823.67 / 7.21
Ratio of driving wheelbase to overall engine wheebase 0.64 0.64 0.65 0.65 0.63
Overall Wheelbase (engine & tender) (ft / m)53.87 / 16.4253.87 / 16.4252.37 / 15.96
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)170,000 / 77,111172,500 / 78,245175,000 / 79,379176,400 / 80,014185,500 / 84,141
Engine Weight (lbs / kg)195,000 / 88,451192,300 / 87,226198,000 / 89,811199,000 / 90,265209,500 / 95,028
Tender Loaded Weight (lbs / kg)112,000 / 50,80294,000 / 42,638114,950 / 52,141114,950 / 52,141114,950 / 52,141
Total Engine and Tender Weight (lbs / kg)307,000 / 139,253286,300 / 129,864312,950 / 141,952313,950 / 142,406324,450 / 147,169
Tender Water Capacity (gals / ML)5500 / 20.834350 / 16.485500 / 20.835500 / 20.835500 / 20.83
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.109 / 8.2010 / 9.1010 / 9.1010 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)71 / 35.5072 / 3673 / 36.5074 / 3777 / 38.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55 / 139755 / 139763 / 160063 / 160055 / 1397
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80225 / 15.50210 / 14.50200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)15" x 34" / 381x86420" x 34" / 508x86415" x 34" / 381x86422" x 30" / 559x76215" x 34" / 381x864
Low Pressure Cylinders (dia x stroke) (in / mm)28" x 34" / 711x86428" x 34" / 711x86428" x 34" / 711x864
Tractive Effort (lbs / kg)36,745 / 16667.2742,036 / 19067.2336,089 / 16369.7141,140 / 18660.8136,745 / 16667.27
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.63 4.10 4.85 4.29 5.05
Heating Ability
Firebox Area (sq ft / m2)208.50 / 19.38214.70 / 19.95182.07 / 14.46182 / 16.91201 / 18.68
Grate Area (sq ft / m2)35 / 3.2535 / 3.2552.30 / 4.8652.30 / 4.8652.30 / 4.86
Evaporative Heating Surface (sq ft / m2)3075 / 285.782219 / 206.232997 / 278.532154 / 200.113646 / 338.85
Superheating Surface (sq ft / m2)468 / 43.49485 / 45.06
Combined Heating Surface (sq ft / m2)3075 / 285.782687 / 249.722997 / 278.532639 / 245.173646 / 338.85
Evaporative Heating Surface/Cylinder Volume442.19179.49430.97163.19524.30
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7000700011,76810,98310,460
Same as above plus superheater percentage7000819011,76812,96010,460
Same as above but substitute firebox area for grate area41,70050,24040,96645,10040,200
Power L1311511,129381012,4113519
Power MT161.59568.93191.99620.44167.29

Principal Dimensions by Steve Llanso of Sweat House Media
ClassY-3 - superheatedY-4Y-4Y-5Y-5
Locobase ID16,421 840 10,272 841 10,273
RailroadNorthern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSAUSA
Whyte2-8-02-8-02-8-02-8-02-8-0
Number in Class1414141010
Road Numbers1200-12131280-12931280-12931214-12231214-1223
GaugeStdStdStdStdStd
Number Built14141010
BuilderNPAlco-SchenectadyAlco-SchenectadyAlco-SchenectadyAlco-Schenectady
Year19141903190319031903
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.5717 / 5.1817 / 5.1815 / 4.5715 / 4.57
Engine Wheelbase (ft / m)23.67 / 7.2126.17 / 7.9826.17 / 7.9823.67 / 7.2123.67 / 7.21
Ratio of driving wheelbase to overall engine wheebase 0.63 0.65 0.65 0.63 0.63
Overall Wheelbase (engine & tender) (ft / m)52.37 / 15.9652.37 / 15.96
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)183,000 / 83,008172,000 / 78,018172,000 / 78,018178,500 / 80,966178,500 / 80,966
Engine Weight (lbs / kg)205,000 / 92,987194,000 / 87,997194,000 / 87,997198,000 / 89,811198,000 / 89,811
Tender Loaded Weight (lbs / kg)114,950 / 52,141114,950 / 52,141114,950 / 52,141114,950 / 52,141114,950 / 52,141
Total Engine and Tender Weight (lbs / kg)319,950 / 145,128308,950 / 140,138308,950 / 140,138312,950 / 141,952312,950 / 141,952
Tender Water Capacity (gals / ML)5500 / 20.835500 / 20.835500 / 20.835500 / 20.835500 / 20.83
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.1010 / 9.1010 / 9.1010 / 9.1010 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)76 / 3872 / 3672 / 3674 / 3774 / 37
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55 / 139763 / 160063 / 160055 / 139755 / 1397
Boiler Pressure (psi / kPa)175 / 12.10200 / 13.80200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 34" / 508x86422" x 30" / 559x76222" x 30" / 559x76222" x 30" / 559x76222" x 30" / 559x762
Tractive Effort (lbs / kg)36,782 / 16684.0539,181 / 17772.2239,181 / 17772.2244,880 / 20357.2544,880 / 20357.25
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.98 4.39 4.39 3.98 3.98
Heating Ability
Firebox Area (sq ft / m2)200 / 18.58188 / 17.47188 / 17.47194 / 18.03194.50 / 18.07
Grate Area (sq ft / m2)52.30 / 4.8652.30 / 4.8652.30 / 4.8652.30 / 4.8652.30 / 4.86
Evaporative Heating Surface (sq ft / m2)2541 / 236.063418 / 317.663418 / 317.663652 / 339.413652 / 339.28
Superheating Surface (sq ft / m2)510 / 47.38
Combined Heating Surface (sq ft / m2)3051 / 283.443418 / 317.663418 / 317.663652 / 339.413652 / 339.28
Evaporative Heating Surface/Cylinder Volume205.54258.96258.96276.69276.69
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation915310,46010,46010,46010,460
Same as above plus superheater percentage10,70810,46010,46010,46010,460
Same as above but substitute firebox area for grate area40,95037,60037,60038,80038,900
Power L110,5516934693464206423
Power MT508.44355.51355.51317.17317.32

  • NP 1256 (1930s Yesteryear Depot photo by Paul Eilenburger)
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