Northern Pacific 4-6-2 "Pacific" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class Q (Locobase 917)

Data from "Heavy 4-6-2 Engine for the Northern Pacific", Railway & Locomotive Engineering, Volume XVI [16], No 8 (August 1903), p. 357. Works numbers were 27317-27322 in December 1902 and 27323-27336 in April 1903.

Firebox heating surface included 22.9 sq ft (2.13 sq m) of arch tubes. Drury (1993) noted that these were among the first Pacifics anywhere and that they set the tone for the next several batches. A note on the Q diagram hosted at the NP Research site AT ([], last accessed 25 April 2008) shows that the first seven were delivered with piston valves, the next eight with slide valves, and the last with Davis counter-balanced slide valves.

R&LE added an aesthetic appraisal: "The wheel spacing and the disposition of the vertical and horizontal lines in its design, [sic] gives to this machine a symmetrical and well balanced appearance."

See Locobase 16369 for the superheated updates that began in 1913.


Class Q - superheated (Locobase 16369)

Data from NP 1 -1929 Locomotive Diagrams, NP Locomotive Datacards, NP Miscellaneous Diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection.

Locobase 917 shows the Northern Pacific's very first class of Pacifics. This entry describes the class when modified with a 32" (813 mm) combustion chamber and superheater, which was first applied in the early 'teens. Installing the combustion chamber required moving the front tubeplate 11" (279 mm) forward, which repositioned the smokebox. In addition, the four-wheel truck had a longer wheelbase. It may be a coincidence that the first batch of updates was appplied to the seven engines delivered with 12" (305 mm) piston valves. But the boiler's substantial makeover may have cost enough to cause the NP to limit the cost by excluding the slide-valve locomotives.

In order of update, the first seven were:

2081 7/13, 2085 8/13, 2086 5/14, 2080 9/15, 2083 4/16, 2082 9/17 , 2084 6/18

The other eight were updated in the late teens and 1920s. After the makeover, 2087, 2089, 2093-2094 had piston valves while 2088, 2095, 2097 used the Universal steam chest adaptation of the slide valve chest.

Those engines not made over were scrapped in the early 1930s. Most of the rest remained in service into the 1940s, five of which (2080-2081, 2084, 2087, and 2093 ran throughout World War II.


Class Q-1 - 2118 (Locobase 16371)

Data from NP Locomotive Data Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. Works numbers were 39488-39507 in May 1906, 39999-40000 in November; 42492-42501 in August 1907

Compared to the first 18 Q-1s (Locobase 918) delivered by Schenectady, these 30 engines had about the same number of tubes as the earlier Qs (Locobase 917)


Class Q-1 - 300 (Locobase 918)

Data from NP Locomotive Data Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. Works numbers were 30228-30233 in April 1903; 31073-31084 in June 1905.

According to Drury (1993), these engines differed from the Qs (Locobase 917) in having larger boilers with a noticeable taper, outside frames on the trailing trucks, and 20,000 lb more engine weight. These first 18 engines had 46 more small tubes of a smaller diameter and shorter length than the Qs.

All Q-1s were delivered with 12" (305 mm) piston valves.


Class Q-1 - superheater (Locobase 16370)

Data from NP Locomotive Data Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. Works numbers were 30228-30233 in April 1903; 31073-31084 in June 1905; 39488-39507 in May 1906, 39999-40000 in November; 42492-42501 in August 1907

The saturated boilers of the Q-1s shown in Locobase 918 were modified with superheaters and combustion chambers in a long program. The 2107 was first in 1910. The result was nearly identical to the updates applied to the immediately preceding Q class (Locobase 16369).

2107-2110 were converted to oil-burning using the Von Boden-Ingles burner. 2137, which was completed with a Cole superheater, had it replaced in December 1914.

After the 2107, the next engines - 2132 and 2138 -- underwent conversion almost three years later in May 1913. Several more of the later locomotives were also modified in 1913. The remainder were upgraded over the next decade.

2147 was sent to the Minnesota & International as their 600 in 1931 and returned a decade a decade later. The Du Pont Company (officially E. I du Pont de Nemours) set up the nuclear processing facility in Hanford, Wash, a mammoth effort that included construction of 158 miles (254 km) of railroad. The facility leased the 2127 and 2139 in June 1943 and the 2122 in September of that year. The 2127 was wrecked in January 1944.


Class Q-2 (Locobase 919)

Data from NP TO 1944 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "Cole Four Cylinder Balanced Compound - Northern Pacific Railway", American Engineer and Railroad Journal, Volume 80, No 11 (November 1906), p. 411-414. Works numbers were 39999-40000 in November 1911. (Locobase is struck by the royal quality of the two works numbers. One had four 9s and finished off a 10,000 series, and the next had four 0000s and started the next 10,000.)

Firebox heating surface included 8.9 sq ft (0.83 sq m) of arch tubes. Built as Cole balanced compounds in 1906 and celebrated as such in Railway Age, these engines had inside admission for the high-pressure piston valves, outside for the low-pressure ones. All of piston valves measured 14" (356 mm) in diameter each. The inside HP cylinders were set at an incline to clear the lead truck.

One advantage claimed for the four-cylinder compound was the reduction of hammer-blow on the rails. Also, tests suggested an increase in horsepower through compounding without an increase in boiler size.

Obviously, these advantages either were illusory or not worth the trouble as these engines were rebuilt as simple-expansion types in 1909. See Q-3, Q-4 for results.


Class Q-3 (Locobase 920)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004); and DeGolyer, Volume 33, pp. 332+. Baldwin's share ran from 2148 to 2157 (works numbers were 33248-33251, 33277-33282 in March 1909; 33568-33569, 33588-33591 in July 1909 and 33622-33627.

Essentially repeats of the later Q-1s (Locobase 16370), these introduced Walschaert outside radial valve gear to actuate the 12" (305 mm) piston valves. In addition to 8 sq ft (0.74 sq m) in one arch tube, firebox heating surface area included 46.5 sq ft (4.32 sq m) in the combustion chamber.

www.mtmuseum.org/roster/np2156.html (6 June 2005) says that the Q-3s operated primarily on the St. Paul-Duluth section although some were assigned to the North Coast Limited between Livingston and Butte, Montana.

According to the museum, "They were well-liked by the crews, capable of cruising at 95 mph."

But see Locobase's assessment of that claim at entry 6568, the superheated upgrade


Class Q-3 (Locobase 2804)

Data from NP TO 1944 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Three of the Q-3s had larger cylinders, added after they came on the road. Two of these were part of the 10-locomotive batch supplied by Baldwin, the other came from Alco-Schenectady's delivery.

See Locobase 920 for more information and 6568 for the superheated upgrade.


Class Q-3 - superheated (Locobase 6568)

Data from Form 7310 specification/improvement card available on [] (visited 6 June 2005).

This is the superheated version of all converted Q-3 Pacifics (see Locobase 920 & 2804), which differed from the Q-1s shown in Locobases by substituting Walschaert for Stephenson valve gear. According to the spec card, 8 sq ft of firebox heating surface was represented by an arch tube. Steam admission came through 12"(305 mm) piston valves.

An early example of superheating an existing design, this class had a relatively low degree of superheat. A somewhat unusual result of the exercise was a boiler still pressed to the original psi (many such conversions would reduce pressure) and containing more combined heating surface than before.

Locobase skeptically repeats a comment from 920 because it seems more likely with the superheated version: "They were well-liked by the crews, capable of cruising at 95 mph."

Locobase thinks that's a pretty high speed for 69" drivers. At that pace, they were whirling around at 463 rpm and the piston speed topped 2,000 fpm. And while the ratio between heating surface and cylinder volume runs toward the higher end of similar locomotives, it wasn't the highest.


Class Q-4 (Locobase 923)

Data confirmed by locomotive diagrams from 1900 hosted on [] (7 February 2004). See also DeGolyer, Volume 33, pp. 338+; and NP Locomotive Cards supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 33568-33569, 33588-33591 in July 1909; 33619, 33622-33627 in August; 33796-33797, 33847-33850 in September; 33888-33891, 33919-33923, 33944 in October; 33971, 34079-34083 in November; and 34110-34112, 34118-34119, 34136-34137, 34143-34144 in December.

This set of Q-4s were Baldwin's supplement to the Q-3s and were the first to be completed with superheaters installed. All were produced in 1909:

The last two months' of production featured cylinders bored out to 24 1/2". Although some were later relined to reduce their diameters to 23", all would eventually have 24 1/2" cylinders. And all cylinders were supplied through 12" (305 mm) piston valves. The firebox had one arch tube contributing 8 sq ft (0.74 sq m) to heating surface area--a mere pittance--but the combustion chamber added a bit more, adding 46.5 sq ft (4.32 sq m).


Class Q-4 (Locobase 2805)

Alco versions of the larger-cylinder Q-3s. Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004).

Further supplemented by reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's [] (accessed 16 June 2006). 48186-48203 in August 1910.

Firebox heating surface included 8 sq ft of arch tubes. Note how low (14.1%) is the superheat ratio, indicative of how early in the era this design was produced.

In Northern Pacific's Tell Tale (June, 1950) ([]), R. V. Nixon gave the following account of the Q-4 2222.

ORDER NO 222

NO 222 ENG 2222 RUN 2 HOURS LATE TOWNSEND TO LOGAN

DSC

Yes, that's a lot of deuces. but this train order actually was issued on the Rocky Mountain Division when Q-4 engine 2222 was assigned to [T]rains 221 and 222.

The four deuces has had a strenuous career with the N.P. Built by the Schenectady Works of ALCO in 1910, the 2222 was assigned immediately to the North Coast Limited out of Missoula, in which service it remained for nearly 15 years. It was a rugged job. Many enginemen will recall the scenic, but back-breaking run on No. 2 from Paradise to Missoula in the pre-stoker days. It took a first class fireman to keep a full head of steam on the steadily ascending grade from Paradise to Evaro, even though a helper was added at Arlee for the tough 2.2 [percent] grade to the top of the mountain. Needless to say, the 2222 worked at full capacity for the entire distance.

Quite a contrast to the effortless manner in which the present day Diesel-powered No. 2 slithers from Paradise to Evaro, almost oblivious of any climb. But we doubt if a Diesel could present anything as breath-taking and dramatic as the old 2222 barreling around a curve along the Pend d'Oreille River, throttle wide open, rods flashing in the sunlight, and the sharp exhaust emitting a plume of smoke into the clear, mountain air.

On the 50th anniversary of the North Coast Limited it is interesting to note that Q-4 power was standard on the train for a longer period than any other class of locomotive. The N.P. purchased a total of 49 Q-4s from Baldwin and Alco. Of these, 25 still remain in service, including the 2222 which is now taking it easy as a protection engine at Spokane


Class Q-5 (Locobase 925)

Data from "Heavy Power for the Northern Pacific," Railway Age Gazette, Volume 71, No. 17 (22 October 1929), pp.767-769, confirmed and supplemented by NP TO 1944 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

4 arch tubes of 3 1/2" diameter supported the firebox's brick arch; these contributed 35 sq ft to the firebox's heating surface. 14" piston valves supplied steam to the cylinders.

According to Drury (1993) these twenty engines were designed to weigh 296,000 lb with no more than 62,500 lb on an axle. They were also to cost no more than current engines of similar size. A year after their delivery, RAG explained that they were intended for the Dilworth, Minn -Missoula, Mont. section of the road, which included 2.3% grades and 16-deg curves. On that section, the Q-5 would have 12-car trailing load with 17-car trains not unheard of. RAG claimed that weight on the drivers came to 181,000 lb and total engine weight to 314,000 lb. RAG calculated that these engines developed their maximum horsepower at 46.5 mph.

Drury contends that when Brooks delivered the Q-5s in 1920, however, axle load had grown to 65,433 lb, total weight to 323,700 lb and the price to $70,916. Also, they were seen as more complicated and harder to maintain. Variable-lead valve gear proved so daunting to adjust at first that the NP set the maximum speed at 55 mph, considerably less than hoped. NP soon worked out the bugs and the railroad ordered another 20 as Q-6s.


Class Q-6 (Locobase 926)

Data from "Extensive Order for New Locomotives for the Northern Pacific Railway Company," Railway and Locomotive Engineering, Vol XXXV, No. 2 (February 1922), pp. 35-36. Data confirmed by locomotive diagrams from 1900 hosted on [] (7 Feb 2004).

2261-2265 differed only in the use of oil as a fuel; they had 3,500-gal oil capacity tenders. Six (2252-2257) had 11,000-lb boosters.

Diagram shows 14" (356 mm) diameter piston valves. RLE noted that Brooks welded the boiler seams instead of riveting and formed the crown and side sheets as a single piece (which obviated either welding or riveting). The combustion chamber also consisted of one piece of steel that was butt-welded along the bottom and to the crown sheet at the top. The entire frame, save for the tender, was made of cast steel.

Locobase likes to reproduce the "specialty" suppliers when he encounters such a list as it portrays the network of components and companies that contributed to steam-locomotive manufacture in the US. For these Pacifics, RLE reported the following:

American Arch Co.'s brick arch in five sections, supported on four 3 1/2 in. tubes

coal pusher on tender

Franklin Railway Supply Co.'s No. 8 butterfly fire-door

Commonwealth Steel Co.'s cradle at rear of frames

Hunt-Spiller gun iron cylinder and valve chamber bushings

cylinder cocks operated by Hancock pneumatic operating cylinders

driving axles+hammered open-hearth, oil heat treated steel+hollow bored

Elvin grease cellars

Hancock non-lifting injectors

Pyle National back-up lamp

Adams & Westlake marker lamps equipped with tungsten marker lamps

Hancock line checks and strainers

Detroit lubricators

Ohio Injector Company's Chicago flange lubricators on front drivers

Adreon-Campbell graphite lubricators

Hancock guide oil cups

Brunker force feed air piping attachment connected to oil supply pipes between sight feed and air cylinder of compressor

King type U. S. metallic packing on piston rods and valve stem

Wilbert grease lubricators on piston rods

Mellin reverse gear with oil piston

Barco automatic smoke box blower fittings

double sanders equipped with Viloco duplex sander valve

three 3 1/2 in. Consolidated safety valve with the encased pops

balanced throttle valve top opening with drifting valve in dome

Hancock 2 l/2 in. double vertical check valve with double stop valve

Smith adjustable hub liners on all driving wheels

Smith adjustable hub plates on trailing truck wheels

Principal Dimensions by Steve Llanso of Sweat House Media
ClassQQ - superheatedQ-1 - 2118Q-1 - 300Q-1 - superheater
Locobase ID917 16,369 16,371 918 16,370
RailroadNorthern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class2015304848
Road Numbers280-299/2080-20992080-2086, 2094,2118-2147300-317/2100-21472100-2147
GaugeStdStdStdStdStd
Number Built203048
BuilderAlco-SchenectadyNPAlco-SchenectadyAlco-SchenectadyNP
Year19031903190619041913
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6612 / 3.6612 / 3.6612 / 3.6612 / 3.66
Engine Wheelbase (ft / m)33 / 10.0633 / 10.0632.50 / 9.9132.50 / 9.9132.50 / 9.91
Ratio of driving wheelbase to overall engine wheebase 0.36 0.36 0.37 0.37 0.37
Overall Wheelbase (engine & tender) (ft / m)58.37 / 17.7958.37 / 17.7962.04 / 18.9162.04 / 18.9162.04 / 18.91
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)132,000 / 59,874132,600 / 60,146146,300 / 66,361142,500 / 64,637144,000 / 65,317
Engine Weight (lbs / kg)196,000 / 88,904205,000 / 92,987223,000 / 101,151219,000 / 99,337225,500 / 102,285
Tender Loaded Weight (lbs / kg)123,400 / 55,973123,400 / 55,973128,500 / 58,287128,500 / 58,287128,800 / 58,423
Total Engine and Tender Weight (lbs / kg)319,400 / 144,877328,400 / 148,960351,500 / 159,438347,500 / 157,624354,300 / 160,708
Tender Water Capacity (gals / ML)6000 / 22.736000 / 22.737000 / 26.526000 / 22.736000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.9012 / 10.9012 / 10.9012 / 10.9012 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)73 / 36.5074 / 3781 / 40.5079 / 39.5080 / 40
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175369 / 175369 / 175369 / 175369 / 1753
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 26" / 559x66022" x 26" / 559x66022" x 26" / 559x66022" x 26" / 559x66022" x 26" / 559x660
Tractive Effort (lbs / kg)31,004 / 14063.1931,004 / 14063.1931,004 / 14063.1931,004 / 14063.1931,004 / 14063.19
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.26 4.28 4.72 4.60 4.64
Heating Ability
Firebox Area (sq ft / m2)198.20 / 18.41248 / 23.04241 / 22.39188.40 / 17.51241 / 22.39
Grate Area (sq ft / m2)47.20 / 4.3847.20 / 4.3843.50 / 4.0443.50 / 4.0443.50 / 4.04
Evaporative Heating Surface (sq ft / m2)3463 / 321.722399 / 222.872926 / 271.833549 / 329.832398 / 222.78
Superheating Surface (sq ft / m2)444 / 41.25444 / 41.25
Combined Heating Surface (sq ft / m2)3463 / 321.722843 / 264.122926 / 271.833549 / 329.832842 / 264.03
Evaporative Heating Surface/Cylinder Volume302.73209.72255.79310.25209.63
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation94409440870087008700
Same as above plus superheater percentage944010,9508700870010,092
Same as above but substitute firebox area for grate area39,64057,53648,20037,68055,912
Power L1895515,3518306903015,279
Power MT448.69765.68375.49419.11701.76

Principal Dimensions by Steve Llanso of Sweat House Media
ClassQ-2Q-3Q-3Q-3 - superheatedQ-4
Locobase ID919 920 2804 6568 923
RailroadNorthern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class22032331
Road Numbers2175-21762148-21702153, 2161, 21692148-21702177-2207
GaugeStdStdStdStdStd
Number Built220331
BuilderAlco-SchenectadyseveralseveralNPBaldwin
Year19061909190919141909
Valve GearWalschaertWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6612 / 3.6612 / 3.6612 / 3.6612 / 3.66
Engine Wheelbase (ft / m)33.41 / 10.1832.50 / 9.9132.50 / 9.9132.50 / 9.9132.50 / 9.91
Ratio of driving wheelbase to overall engine wheebase 0.36 0.37 0.37 0.37 0.37
Overall Wheelbase (engine & tender) (ft / m)62.83 / 19.15
Axle Loading (Maximum Weight per Axle) (lbs / kg)53,800
Weight on Drivers (lbs / kg)157,000 / 71,214150,000 / 68,039150,000 / 68,039146,200 / 66,315141,900 / 64,365
Engine Weight (lbs / kg)240,000 / 172,592236,000 / 107,048236,000 / 107,048236,000 / 107,048237,600 / 107,774
Tender Loaded Weight (lbs / kg)141,500 / 64,115141,350 / 64,115141,350 / 64,115141,350 / 64,115145,300 / 65,907
Total Engine and Tender Weight (lbs / kg)381,500 / 236,707377,350 / 171,163377,350 / 171,163377,350 / 171,163382,900 / 173,681
Tender Water Capacity (gals / ML)7000 / 26.527000 / 26.527000 / 26.527000 / 26.527000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.9012 / 10.9012 / 10.9012 / 10.9012 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)87 / 43.5083 / 41.5083 / 41.5081 / 40.5079 / 39.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175369 / 175369 / 175369 / 175369 / 1753
Boiler Pressure (psi / kPa)220 / 15.20200 / 13.80200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)16.5" x 26" / 419x66022" x 26" / 559x66024.5" x 26" / 622x66022" x 26" / 559x66023" x 26" / 584x660
Low Pressure Cylinders (dia x stroke) (in / mm)27.5" x 26" / 699x660
Tractive Effort (lbs / kg)28,211 / 12796.3131,004 / 14063.1938,451 / 17441.1031,004 / 14063.1933,887 / 15370.90
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.57 4.84 3.90 4.72 4.19
Heating Ability
Firebox Area (sq ft / m2)241.80 / 22.47242 / 22.48242 / 22.49241 / 22.40235 / 21.83
Grate Area (sq ft / m2)43.50 / 4.0443.50 / 4.0443.50 / 4.0443.50 / 4.0443.50 / 4.04
Evaporative Heating Surface (sq ft / m2)2909 / 270.352926 / 271.832926 / 271.932620 / 243.492450 / 227.61
Superheating Surface (sq ft / m2)444 / 41.26391 / 36.32
Combined Heating Surface (sq ft / m2)2909 / 270.352926 / 271.832926 / 271.933064 / 284.752841 / 263.93
Evaporative Heating Surface/Cylinder Volume452.09255.79206.25229.04195.96
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation95708700870087008700
Same as above plus superheater percentage95708700870099189918
Same as above but substitute firebox area for grate area53,19648,40048,40054,94853,580
Power L158298316670515,72513,142
Power MT245.56366.67295.64711.37612.54

Principal Dimensions by Steve Llanso of Sweat House Media
ClassQ-4Q-5Q-6
Locobase ID2805 925 926
RailroadNorthern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSA
Whyte4-6-24-6-24-6-2
Number in Class182020
Road Numbers2208-22252226-22452246-2265
GaugeStdStdStd
Number Built182020
BuilderAlco-SchenectadyAlco-BrooksAlco-Brooks
Year191019201922
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6614 / 4.2713.17 / 4.01
Engine Wheelbase (ft / m)32.50 / 9.9135.59 / 10.8536.75 / 11.20
Ratio of driving wheelbase to overall engine wheebase 0.37 0.39 0.36
Overall Wheelbase (engine & tender) (ft / m)61.92 / 18.8771.30 / 21.73
Axle Loading (Maximum Weight per Axle) (lbs / kg)65,433 / 29,68064,100 / 29,075
Weight on Drivers (lbs / kg)155,100 / 70,352196,300 / 89,040199,900 / 90,673
Engine Weight (lbs / kg)237,000 / 107,502318,900 / 144,651323,900 / 146,919
Tender Loaded Weight (lbs / kg)145,300 / 65,907199,600 / 90,537198,500 / 90,038
Total Engine and Tender Weight (lbs / kg)382,300 / 173,409518,500 / 235,188522,400 / 236,957
Tender Water Capacity (gals / ML)7000 / 26.5210,000 / 37.8810,000 / 37.88
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.9014 / 12.7014 / 12.70
Minimum weight of rail (calculated) (lb/yd / kg/m)86 / 43109 / 54.50111 / 55.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175373 / 185473 / 1854
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)24.5" x 26" / 622x66026" x 28" / 660x71126" x 28" / 660x711
Tractive Effort (lbs / kg)38,451 / 17441.1044,079 / 19993.9244,079 / 19993.92
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.03 4.45 4.54
Heating Ability
Firebox Area (sq ft / m2)240 / 22.30335 / 31.13335 / 31.12
Grate Area (sq ft / m2)43.50 / 4.0470.30 / 6.5370.30 / 6.53
Evaporative Heating Surface (sq ft / m2)2455 / 228.163419 / 317.753461 / 321.53
Superheating Surface (sq ft / m2)404 / 37.55928 / 86.25928 / 86.21
Combined Heating Surface (sq ft / m2)2859 / 265.714347 / 4044389 / 407.74
Evaporative Heating Surface/Cylinder Volume173.05198.71201.15
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation870014,06014,060
Same as above plus superheater percentage991817,01317,013
Same as above but substitute firebox area for grate area54,72081,07081,070
Power L111,82019,01619,075
Power MT504.03640.70631.11

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