The Norfolk & Western had a large fleet of 2-8-8-2s. The first of them was built in 1910. The wheel arrangement was in use on the N&W as late as 1960. The last batch was built between 1942 and 1952 and represented one of the most advanced Mallet locomotives in the USA.
Steam locomotives employing compound compression have been around since the 1880s. One of the main advantages of using compound compression is to extract more energy out of the steam thus increasing efficiency. Superheating was another method used to increase efficiency with less maintenance but compound Mallets continued to be built as late as the early 1950s by the Norfolk & Western.
When starting a stationary compound locomotive, the high-pressure cylinders will receive the initial steam and perform all of the work while the larger, low-pressure cylinders have yet to receive any steam (exhausted from the high-pressure cylinders). To alleviate this imbalance, compound locomotives were equipped with an intercepting valve (sometimes called a sampling valve). The intercepting valve was used to temporarily switch the locomotive from compound expansion mode (normal) to simple expansion mode for starting. It was like an on/off switch that would allow high pressure to the front cylinders. It could only be set one way or the other.
The Norfolk & Western also used a reducing valve in their compound locomotives. The reducing valve was used to automatically regulate the steam pressure supplied to the low-pressure cylinders. When run in simple mode, the reducing valve would control how much pressure was supplied to the low-pressure cylinders. If desired, when running in compound mode, the reducing valve could be manually adjusted to allow a small amount of superheated boiler steam to the receiver, thus raising the pressure and temperature of the steam sent to the low-pressure cylinders. Instead of being driven with steam at a pressure of 85 to 90 psi, the low-pressure cylinders would operate with steam at 100 to 110 psi. On the Norfolk & Western, this valve was commonly called the "booster" valve. Of course, using the reducing valve in this way made the locomotive a bit less efficient. Another drawback of using this valve to admit more high-pressure steam to the low-pressure cylinders was that it made the front, low-pressure engine, more slippery. As a result, lead weight was added to the front bed casting of the Y5/Y6 to provide better traction.
Data from Record of Recent Construction #67 (Baldwin Locomotive Works, 1910), p.28-29. See also DeGolyer, Volume 34, pp. 124+. (Thanks to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10.). Works numbers were 34671-34672 and 34696-34698 in May 1910.
Baldwin was experimenting with all kinds of moderate-superheat systems, claiming to believe that such designs were kinder to the locomotive than the higher-temperature kinds. Thus, the heating surface number in the first class of Mallets for the N & W include some uncommon devices that did not contribute anything like the supplemental power that the Schmidt superheater made available.
Between the Baldwin smokebox reheater (which was credited with 586 sq ft/54.44 sq m) and the firetubes themselves was Baldwin's feed water heater in a "separable" boiler. This was a bundle of 450 2 1/4" (57 mm) tubes that filled the boiler's cross-section; water surrounded the tubes and thus was pre-heated before being admitted to the rear boiler to be turned to steam. The reheater in the smokebox intercepted the steam as it left the HP cylinders, dried it out to some degree, and admitted to the LP cylinders.
All four cylinders were fed by large 15" (381 mm) diameter piston valves. The N&W calculated compound tractive effort as 66,892 lb (30,383 kg or 297.55 kN) and starting tractive effort with all cylinders fed live steam 83,615 lb (37,927 kg or 371.94 kN).
See Locobase 13802 for an extended look at the Y-1s' rival, the Alco-Schenectady-built X1 0-8-8-0s. Locobase lifts a paragraph from that entry as a summary in this one:
Which design better suited the purpose of moving freight over the road? Well, according to Drury (1993), "Tests showed the X1 was the better performer, but the leading and trailing trucks of the Y1 gave it better riding stability." He also points out that the Y1s were retired in 1924 because of their complicated separable boilers, while the N&W superheated the X1s and raised their boiler pressures to 230 psi..
Data from "Norfolk & Western's Mallet", Railway Journal, Volume 24 (August 1918), pp. 19-20; "N&W 267-ton Mallet Locomotive", Railway Mechanical Engineer, Volume 92, No 8 (August 1918), pp. 445-450 and "Results of Road Tests of N&W Mallet Locomotive," Volume 92, No 9 (September 1918), pp. 502-503. (Thanks to Chris Hohl for his 21 November 2013 email that noted the sale of fifteen Y-2/Y-2as to the Denver & Rio Grande Railway in 1943; see below. Thanks also to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10.
(Special thanks to Eric Bott for his 13 November 2023 email describing some confusing information in these comments caused by Locobase's misunderstanding of what locomotives came when. Our interaction led to the use of two entries to differentiate between the original Y-2s and their upgrades to Y-2a (Locobase 3560 ).
The first of a long line of compound Mallet Consolidations, Y2s appeared in several batches. Roanoke designed and built eleven (works numbers 224-258 in 1918, 226 in 1919, 227-228 in 1921, and 229 in January 1921, 230-232 in February, and 233-234 in April).
All cylinders used piston valves, the HP diameter taking 14" (356 mm) and the LP cylinders 17" (432 mm). The N&W calculated compound tractive effort as 104,300 lb (47,310 kg or 463.95 kN) and starting tractive effort with all cylinders fed live steam 123,960 lb (56,227 kg or 551.40 kN).
Baldwin supplied twenty in 1918-1919 to USRA standards (Locobase 330) as shown in the spec above.They had works numbers 51036 in January 1919, 51341 in February; 51514, 51557 in March; 51678, 51699, 51700 in April, 51813 in May,;51866, 51880, 51936-51937 in June; 52298, 52317-52319, 52351 in September; 52469 in October; and 52676, 52707 in December.
Heating surface area in the electrically welded firebox included 45 sq ft (4.2 sq m) in five arch tubes and 134 sq ft (12.45 sq m) in the combustion chamber. All cylinders used 14" (356 mm) piston valves. The fireman must welcomed the Duplex mechanical stoker that came standard.
RME noted that many of the components and other aspects of the design were sized to deliver the most power within a limited set of clearances. For example, using a thinner plate (13/16"/20.6 mm) in the fourth boiler ring over the combustion chamber saved over 3,000 lb (1,361 kg). RME also notes the use of a Sentinel low-water alarm, which was intended to reduce the tendency to carry too high a water level in the boiler (as a conservative measure to avoid boiler explosions) and thus compromise the efficiency of the superheater.
Roanoke followed with six more in 1924; works numbers were 229-234. The earlier engines were all upgraded to the Y2a configuration and all eventually used 25" (635 mm) diameter HP cylinders. Other than that, the Y2as were not much changed throughout their careers.
One of the class--1702--was fitted in 1927 with Franklin reversible boosters in its two tender trucks. Starting tractive effort was calculated at 33,900 lb (15,377 kg or 138.48 kN).
As the N&W added more modern articulateds, the railway sold half of its Y-2/Y-2as in 1943 to the Denver & Rio Grande Western to boost their power in the face of wartime demands. Classed by the D&RGW as L-109s, the engines were numbered 3550-3594 as follows:
Road numbers D&RGW former N&W Month transferred
3550 1701 April
3551 1722 April
3552 1724 April
3553 1728 April
3554 1729 June
3555 1730 June
3556 1710 August
3557 1727 June
3558 1706 May
3559 1709 May
3560 1713 May
3561 1714 May
3562 1719 May
3563 1725 May
3564 1726 May
Data from Richard Prince, Norfolk & Western Railway, Pocahontas Coal Carrier (Millard, NE: Richard E Prince, 1980).
Prince also reports that the Utah Copper Company bought 1721 and 1723 for the Bingham & Garfield in June 1943. The B&G did not renumber the pair.
The remaining thirteen locomotives were scrapped in 1948-1945
Data from "Mallets Built in Norfolk & Western Shops", Railway Journal (June 1924), pp. 30-31; and N&W 3-1955 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Special thanks to Eric Bott for his 13 November 2023 email describing some confusing information in these comments caused by Locobase's misunderstanding of what locomotives came when. Our interaction led to the use of two entries to differentiate between the original Y-2s (Locobase 16662) and their upgrades shown here.)
Locobase 16662 describes the original Y-2 design as produced by Roanoke and Baldwin in 1918-1919. Although successful , Roanoke's shops took account of the Y-2s' operating experience to update a variety of components "[M]ain and side rods, knuckle pins, guides, crossd heads, guide yokes, lubricators, water glasses, nozzles, cylinder cocks, etc." all were reworked to be "much more substantial and serviceable, in the interest of reducing failure on the road."
One of the class--1702--was fitted in 1927 with Franklin reversible boosters in its two tender trucks. Starting tractive effort was calculated at 33,900 lb (15,377 kg or 138.48 kN). Others had Bethlehem tender boosters.
Over their careers, Y-2a boiler pressures increased to 265 and 270 psi (18.28 bar and 18.62 bar).and their tender water capacity increased by 50% and coal by 30%.
As the N&W added more modern articulateds, the railway sold half of its Y-2/Y-2as in 1943 to the Denver & Rio Grande Western to boost their power in the face of wartime demands. Classed by the D&RGW as L-109s, the engines were numbered 3550-3594 as follows:
Road numbers D&RGW former N&W Month transferred
3550 1701 April
3551 1722 April
3552 1724 April
3553 1728 April
3554 1729 June
3555 1730 June
3556 1710 August
3557 1727 June
3558 1706 May
3559 1709 May
3560 1713 May
3561 1714 May
3562 1719 May
3563 1725 May
3564 1726 May
Data from Richard Prince, Norfolk & Western Railway, Pocahontas Coal Carrier (Millard, NE: Richard E Prince, 1980).
Prince also reports that the Utah Copper Company bought 1721 and 1723 for the Bingham & Garfield in June 1943. The B&G did not renumber the pair.
The remaining thirteen locomotives were scrapped in 1948-1945
Data from N&W 3-1955 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "N& W Applies Power Tender Trucks for Hump Yard Service", Railway Age, Volume 85, (14 July 1928), pp. 59-60; and American Locomotive Company, "Standardized Locomotive Built for the United States Railroad Administration, Pamphlet No 10049 (New York: American Locomotive Company, 1919), reprinted 1973 by Specialty Press (Ocean [sic, should be Ocean Township), New Jersey
(Thanks to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10. Thanks, too, to Chris Hohl whose earlier email provided the post-N&W details of this class's history. Thanks as well to Eric Bott, whose 13 November 2023 email cleared up some confusing comments about how production was apportioned. Thanks to Chris Hohl for his 21 June 2023 email correcting the adhesion, engine, and total wheelbases.)
Alco-Schenectady works numbers were 61073-61088 in April 1919, 61089-61112 in May. Alco-Richmond's works numbers were 64070-64079 in March 1923, 64080-64089 in April, 64090-64091 in May, 64092-64099 in June. Baldwin's works numbers were 52157, 52189, 52226, 52250-52251 in August 1919.
This design first came to the N&W as an example of the USRA heavy articulated design (Locobase 330), which itself was based on Norfolk & Western's Y2. Firebox heating surface then included 134 sq ft (12.45 sq m) of arch pipes and syphons, boiler pressure was set at 240 psi (16.5 bar), and the piston valves measured 14" (356 mm) in diameter. The N&W calculated compound tractive effort as 114,154 lb (51,779 kg or 507.78 kN) and starting tractive effort with all cylinders fed live steam 136,985 lb (62,135 kg or 609.34 kN).
The original tender weighed 80,000 lb (36,287 kg) tare and 209,100 lb (94,946 kg) when loaded with 12,000 US gallons (45,420 litres) of water and 16 tons (14.45 metric tons) of coal. in 1918, total engine & tender wheelbase measured 94 ft 6 in (28.80 m).
2006 received a tender with Bethlehem side-rod-driven tender boosters on each of the two trucks in 1927; combined additional tractive effort measured 34,500 lb (15,650 kg/153.46 kN).
Alco-Schenectady built 45, Baldwin added 5. In 1923, Alco-Richmond delivered 30 more Y3a, which were similar except for a larger tender. Over time the Y3s received a Worthington feed water heater and a different boiler with 30 fewer tubes, but higher boiler pressure, more superheat and a firebox with 65 sq ft (6.04 sq m) of arch tubes. That version is the one shown in the specifications.
Most of both classes that remained with the Norfolk & Western served until 1957-1959.
During World War Two, the N&W sold several Y-3s to other railroads who needed big freight locomotives, but couldn't build them because of wartime production constraints. The Santa Fe bought eight in 1943-- N&W road numbers 2021-2022, 2015, 2026, 2014, 2029, 2035, 2042--which they renumbered 1790-1797 and put to work as helpers on the Raton Pass that crossed the Colorado-New Mexico border.
After the war, the Santa Fe scrapped the 1797 (ex-2042), and sold the other seven to the Virginian as their class USE, road numbers 736-742. The Virginian operated all seven for another seven-eight years before retiring them in 1954-1955.
The Pennsylvania bought class leader 2000 as well as 2008, 2027, 2034, 2036, and 2046 in 1943. (The 2046 was the only Baldwin-built Y-3 sold; the others all came from Alco.) Redesignating them HH1 and numbering 373-378, the Pennsy operated the sextet on drag freights between Hagerstown, Md and Harrisburg, Pa. After World War Two ended, the HH1s were reassigned to the Columbus, Ohio area until they were retired in 1947-1949.
Union Pacific bought five in June 1945--N&W 2030, 2020, 2025, 2041, 2013--which they redesignated MC-57 and numbered 3670-3674. After they operated for two years in Wyoming, the UP scrapped the class.
Data from N&W 12-1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for the valve gear ID. Thanks also to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10.). Works numbers were 67130-67139 in January 1927.
Firebox had combustion chamber. All four piston valves measured 10" (254 mm) each. Mallet compounds built in a total of eight batches. The ten Y-4s were originally classed as Y-3bs. The large LP cylinders posed some problems in steam exhausting due to the internal design of steam lines, ports, and valves. The N&W calculated compound tractive effort as 114,154 lb (51,779 kg or 507.78 kN) and starting tractive effort with all cylinders fed live steam 136,985 lb (62,135 kg or 609.34 kN).
Updates later in their careers included a Worthington 4 1/2 BL feed water heater, and an increase in boiler pressure to 270 psi (18.6 bar). Tender capacity increased considerably to 24,000 US gallons (90,480 litres) and 27 tons (24.5 of coal
Later N&W engines were built to a larger design; see the Y-6 record.
Data from N&W 3-1955 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10.). Works numbers 246-254 were delivered as Y-4a in 1930, 255-264 arrived as Y-5 in 1931.
Continuation of the N&W series of large Mallet compounds, the Y-5s were first introduced in 1930 as the first "modern" 2-8-8-2s, according to EL King in Drury (1993). In addition to the 300-psi boiler, these engines had the "waffle-iron" nozzles for the low-pressure cylinder exhaust that reduced back pressure. They also had a prominent external steam bridge pipe that formed a shallow, inverted V between the two fron cylinders. Beginning with the Y5s, the railway's calculated compound tractive effort was 126,838 lb (57,533 kg or 564.2 kN) and 152,206 lb (69,040 kg or 677.0 kN) working simple.
The Y4s' outdated fabricated frames couldn't handle the immense power generated by the boiler and cylinder combination and at first they ate up maintenance time. In 1940-1941, however, ten of the remaining Y-4as--2094, 2090, 2098, 2096, 2095, 2100, 2091, 2097, 2099, and 2093--were rebuilt with cast-steel frames and cylinders. They also received Worthington BL feed water heaters.
This fixed the wracking problem and the Y-5s, now virtually identical to the later Y-6s, served out steam on the Norfolk & Western.
Data from N&W 3-1955 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10. Thanks also to Chris Hohl for his 12 November 2020 email noting the original tender's fuel capacity.) Y-6 works numbers were 268-272, 281-310 in 1973-1940. Y-6a continued with 316-331 in 1942.
Continuation of the N&W series of large Mallet compound with the final signficant change in the basic design Y-6 series engines had integrally cast cylinders in cast-steel frames, Beginning with the Y5s, the railway's calculated compound tractive effort was 126,838 lb (57,533 kg or 564.2 kN) and 152,206 lb (69,040 kg or 677.0 kN) working simple.
Timken roller bearings on all axles, Worthington feed water heater, and piston valves as large as 18" (457 mm) in diameter. The 2154-2170 engines' Baker valve gear used McGill multirol bearings. When delivered, the Y-6s trailed tenders carrying 26 tons of coal fuel; tender soon increased to the 30 tons shown in the specs. All engines soon received 58" drivers (1,473 mm).
Unlike some of the earlier classes of 2-8-8-2s, none of the Y-6 Mallets left the N&W. All continued to operate until they were retired and scrapped in 1959-1960.
Data from N&W 3-1955 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also William Withuhn, American Steam Locomotives: Design and Development 1880-1950 (Indianapolis and Pflugerville, TX: Indiana University Press and Railway & Locomotive Historical Society, 2019), pp. 391-399.(Thanks to Chris Hohl for his 3 January 2018 email pointing out the Y-6b's 58" diameter drivers. Thanks also to Greg Mills for his series of March 2018 emails commenting on the N&W's series of 2-8-8-2 and providing the publishing cite for William E Warden, Norfolk & Western's Magnificent Mallets (Lynchburg, VA:TLC Publishing, 1996), see especially page 10.). Works numbers were 363-379 in 1948-1949, 391-396 in 1950, and 397, 414-415 in 1951, and 416-419 in 1952.
Beginning with the N&W Y5s, the railway's calculated compound tractive effort was 126,838 lb (57,533 kg or 564.2 kN) and 152,206 lb (69,040 kg or 677.0 kN) working simple. HP piston valves measured 14" (356 mm) in diameter while the LP valves had an 18" (457 mm) bore.
Greg Mills noted in his 30 March 2018 email that the Y6b used "variable valve plumbing" in the LP cylinders to allow simple-expansion steaming in all four cylinders at all speeds, "not just at startup." He adds that the railway "had to add some 26 tons of lead to the front engine frame to prevent slipping." Despite the extra weight, the engine's factor of adhesion operating simple dropped to 3.60.
Heating surface data from N&W diagram book in Allen Stanley's large Rail Data Exchange. Stanley also includes data on the extended combustion chamber variant. The tube and flue areas remained the same, but the superheater was reduced by 60 sq ft (5.57 sq m) and the arch tubes by 41 sq ft (3.81 sq m) while adding 100 sq ft (9.29 sq m) of circulators. The engine also used a Worthington 6 SA feed water heater.
Last in a series of compound articulated locomotives that ranked as the best. See earlier entries on the Y-3, Y-4, Y-5, and Y-6 (Locobases 1421, 323, 4396, and 324). All axles had Timken roller bearings and the valve gear used McGill multirol bearings.
Pulling a load of 13,500 tons (12,273 tonnes) on the level at 25 mph, the Y-6b developed 5,500 indicated horsepower (cut-off of the HP cylinders of 60% and in the LP cylinders 55%). In his 30 March 2018 email, Mills directly compares the Y6bs and the Union Pacific's Big Boys (Locobases 346 and 13026) and concludes: "Considering weight on the rails, power to weight ratios, overall length, practical speeds (which nearly doubled that of the earlier compound Y series), economy of operation, and quantity built, this appears to be the most successful articulated locomotive ever built."
E W King, Jr. (in Drury, 1993) summarizes the story: "In tinkering with the design over a period of 33 years, the road wound up with a locomotive capable of producing 5,600 drawbar horsepower at 25 mph (40 km/h) with a top speed of 50 mph (81 km/h) -- perfect matches for N&W's tonnage, grades, and curves ... while retaining the economies of compound operation and in a locomotive that weighed 100,000 lb less than either the [C&O's] 2-6-6-6 or [UP's] 4-8-8-4 [Big Boy]."
These engines were carefully maintained and well-designed, yielding to diesels only because the N&W could no longer afford to be the "odd man out" in the diesel parade. The last Y-6 was completed in 1952, and the last one ran in April 1960..
| Principal Dimensions by Steve Llanso of Middle Run Media | |||||
|---|---|---|---|---|---|
| Class | Y-1 | Y-2 | Y2a | Y3/Y3a (USRA) | Y3b/Y4 |
| Locobase ID | 10991 | 16662 | 3560 | 1421 | 323 |
| Railroad | Norfolk & Western (N&W) | Norfolk & Western (N&W) | Norfolk & Western (N&W) | Norfolk & Western (N&W) | Norfolk & Western (N&W) |
| Country | USA | USA | USA | USA | USA |
| Whyte | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 |
| Number in Class | 5 | 31 | 31 | 80 | 10 |
| Road Numbers | 995-999 | 1700-1730 | 1700-1730 | 2000-2079 | 2080-2089 |
| Gauge | Std | Std | Std | Std | Std |
| Number Built | 5 | 31 | 31 | 80 | 10 |
| Builder | Baldwin | several | several | Several | Alco-Richmond |
| Year | 1910 | 1918 | 1923 | 1919 | 1927 |
| Valve Gear | Walschaert | Baker | Baker | Baker | Baker |
| Locomotive Length and Weight | |||||
| Driver Wheelbase (ft / m) | 31 / 9.45 | 31 / 9.45 | 31 / 9.45 | 31.50 / 9.60 | 31.50 / 9.60 |
| Engine Wheelbase (ft / m) | 55.50 / 16.92 | 57.33 / 17.47 | 57.33 / 17.47 | 58 / 17.68 | 58 / 17.68 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.56 | 0.54 | 0.54 | 0.54 | 0.54 |
| Overall Wheelbase (engine & tender) (ft / m) | 83.28 / 25.38 | 101.02 / 30.79 | 101.02 / 30.79 | 102.02 / 31.10 | 98.23 / 29.94 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 65,500 / 29,710 | ||||
| Weight on Drivers (lbs / kg) | 360,000 / 163,293 | 472,000 / 214,096 | 472,000 / 214,096 | 485,200 / 220,083 | 508,500 / 230,652 |
| Engine Weight (lbs / kg) | 390,000 / 176,901 | 535,000 / 242,672 | 526,000 / 238,590 | 539,000 / 244,487 | 567,000 / 257,187 |
| Tender Loaded Weight (lbs / kg) | 170,000 / 77,111 | 212,000 / 96,162 | 312,700 / 141,839 | 312,700 / 141,839 | 271,200 / 123,014 |
| Total Engine and Tender Weight (lbs / kg) | 560,000 / 254,012 | 747,000 / 338,834 | 838,700 / 380,429 | 851,700 / 386,326 | 838,200 / 380,201 |
| Tender Water Capacity (gals / ML) | 9000 / 34.09 | 12,000 / 45.45 | 18,000 / 68.18 | 20,000 / 75.76 | 16,000 / 60.61 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 14 / 13 | 20 / 18 | 26 / 24 | 26 / 23.60 | 23 / 21 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 75 / 37.50 | 98 / 49 | 98 / 49 | 101 / 50.50 | 106 / 53 |
| Geometry Relating to Tractive Effort | |||||
| Driver Diameter (in / mm) | 56 / 1422 | 56 / 1422 | 56 / 1422 | 57 / 1448 | 57 / 1448 |
| Boiler Pressure (psi / kPa) | 200 / 1380 | 230 / 1590 | 240 / 1830 | 270 / 1860 | 240 / 1650 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 24.5" x 30" / 622x762 | 24.5" x 32" / 622x813 | 25" x 32" / 635x813 | 25" x 32" / 635x813 | 25" x 32" / 635x813 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 39" x 30" / 991x762 | 39" x 32" / 991x813 | 39" x 32" / 991x813 | 39" x 32" / 991x813 | 39" x 32" / 991x813 |
| Tractive Effort (lbs / kg) | 78,394 / 35558.96 | 96,163 / 43618.85 | 103,277 / 46845.71 | 114,148 / 51776.72 | 101,465 / 46023.80 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.59 | 4.91 | 4.57 | 4.25 | 5.01 |
| Heating Ability | |||||
| Tubes (number - dia) (in / mm) | 350 - 2.25" / 57 | 285 - 2.25" / 57 | 285 - 2.25" / 57 | 244 - 2.25" / 57 | 260 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 53 - 5.5" / 140 | 53 - 5.5" / 140 | 53 - 5.5" / 140 | 53 - 5.5" / 140 | |
| Flue/Tube length (ft / m) | 21 / 6.40 | 24 / 7.32 | 24 / 7.32 | 24.08 / 7.34 | 24.09 / 7.34 |
| Firebox Area (sq ft / m2) | 210 / 19.51 | 482 / 44.78 | 468 / 43.48 | 453 / 42.08 | 426 / 39.58 |
| Grate Area (sq ft / m2) | 75.20 / 6.99 | 96 / 8.92 | 96.30 / 8.95 | 96 / 8.92 | 96 / 8.92 |
| Evaporative Heating Surface (sq ft / m2) | 5908 / 549.07 | 6316 / 586.77 | 6308 / 586.25 | 5753 / 534.47 | 5932 / 551.30 |
| Superheating Surface (sq ft / m2) | 586 / 54.46 | 1510 / 140.28 | 1567 / 145.63 | 1582 / 146.97 | 1582 / 147.03 |
| Combined Heating Surface (sq ft / m2) | 6494 / 603.53 | 7826 / 727.05 | 7875 / 731.88 | 7335 / 681.44 | 7514 / 698.33 |
| Evaporative Heating Surface/Cylinder Volume | 360.88 | 361.83 | 347.05 | 316.52 | 326.37 |
| Computations Relating to Power Output (More Information) | |||||
| Robert LeMassena's Power Computation | 15,040 | 22,080 | 23,112 | 25,920 | 23,040 |
| Same as above plus superheater percentage | 16,394 | 26,275 | 27,734 | 31,622 | 27,878 |
| Same as above but substitute firebox area for grate area | 45,780 | 131,923 | 134,784 | 149,218 | 123,710 |
| Power L1 | 5505 | 10,827 | 11,518 | 12,903 | 11,492 |
| Power MT | 269.70 | 404.57 | 430.39 | 469.02 | 398.59 |
| Principal Dimensions by Steve Llanso of Middle Run Media | |||
|---|---|---|---|
| Class | Y4a/Y5 | Y6, Y6a | Y6b |
| Locobase ID | 4396 | 324 | 1422 |
| Railroad | Norfolk & Western (N&W) | Norfolk & Western (N&W) | Norfolk & Western (N&W) |
| Country | USA | USA | USA |
| Whyte | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 |
| Number in Class | 10 | 51 | 30 |
| Road Numbers | 2101-2109, 2110-2119 | 2120-2170 | 2171-2200 |
| Gauge | Std | Std | Std |
| Number Built | 10 | 51 | 30 |
| Builder | N&W | N&W | N&W |
| Year | 1930 | 1942 | 1948 |
| Valve Gear | Baker | Baker | Baker |
| Locomotive Length and Weight | |||
| Driver Wheelbase (ft / m) | 31.50 / 9.60 | 31.50 / 9.60 | 31.50 / 9.60 |
| Engine Wheelbase (ft / m) | 58 / 17.68 | 58 / 17.68 | 58 / 17.68 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.54 | 0.54 | 0.54 |
| Overall Wheelbase (engine & tender) (ft / m) | 102.75 / 31.32 | 103.85 / 31.65 | 103.69 / 31.60 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |||
| Weight on Drivers (lbs / kg) | 522,850 / 237,161 | 522,850 / 237,161 | 548,500 / 248,796 |
| Engine Weight (lbs / kg) | 582,900 / 264,399 | 582,900 / 264,399 | 611,520 / 277,381 |
| Tender Loaded Weight (lbs / kg) | 378,600 / 171,730 | 378,600 / 171,730 | 378,600 / 171,730 |
| Total Engine and Tender Weight (lbs / kg) | 961,500 / 436,129 | 961,500 / 436,129 | 990,120 / 449,111 |
| Tender Water Capacity (gals / ML) | 22,000 / 83.33 | 22,000 / 83.33 | 22,000 / 83.33 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 30 / 27 | 30 / 27 | 30 / 27 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 109 / 54.50 | 109 / 54.50 | 114 / 57 |
| Geometry Relating to Tractive Effort | |||
| Driver Diameter (in / mm) | 57 / 1448 | 57 / 1448 | 58 / 1473 |
| Boiler Pressure (psi / kPa) | 300 / 2070 | 300 / 2070 | 300 / 2070 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 25" x 32" / 635x813 | 25" x 32" / 635x813 | 25" x 32" / 635x813 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 39" x 32" / 991x813 | 39" x 32" / 991x813 | 39" x 32" / 991x813 |
| Tractive Effort (lbs / kg) | 126,831 / 57529.64 | 126,831 / 57529.64 | 124,644 / 56537.63 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.12 | 4.12 | 4.40 |
| Heating Ability | |||
| Tubes (number - dia) (in / mm) | 252 - 2.25" / 57 | 223 - 2.25" / 57 | 223 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 53 - 5.5" / 140 | 60 - 5.5" / 140 | 60 - 5.5" / 140 |
| Flue/Tube length (ft / m) | 24 / 7.32 | 24 / 7.32 | 20.05 / 6.11 |
| Firebox Area (sq ft / m2) | 430 / 39.95 | 430 / 39.95 | 555 / 51.56 |
| Grate Area (sq ft / m2) | 106.20 / 9.87 | 106.20 / 9.87 | 106.20 / 9.87 |
| Evaporative Heating Surface (sq ft / m2) | 5822 / 541.08 | 5647 / 524.81 | 4915 / 456.78 |
| Superheating Surface (sq ft / m2) | 1582 / 147.03 | 1775 / 164.96 | 1478 / 137.36 |
| Combined Heating Surface (sq ft / m2) | 7404 / 688.11 | 7422 / 689.77 | 6393 / 594.14 |
| Evaporative Heating Surface/Cylinder Volume | 320.31 | 310.69 | 270.41 |
| Computations Relating to Power Output (More Information) | |||
| Robert LeMassena's Power Computation | 31,860 | 31,860 | 31,860 |
| Same as above plus superheater percentage | 38,551 | 39,506 | 39,188 |
| Same as above but substitute firebox area for grate area | 156,090 | 159,960 | 204,795 |
| Power L1 | 14,307 | 15,313 | 13,759 |
| Power MT | 482.61 | 516.54 | 442.42 |
