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) and the firetubes themselves was Baldwin's feed water heater in a "separable" boiler. This was a bundle of 450 2 1/4" 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" diameter piston valves.
See Locobase 13802 for an extended look at the Y1s' 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..
The first of a long line of compound Mallet Consolidations, Y2s appeared in several batches. Roanoke built five, Baldwin twenty in 1918-1919. 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 piston valves, the HP diameter taking 14" (356 mm) and the LP cylinders 17" (432 mm). The fireman must welcomed the Duplex mechanical stoker that came standard.
RME notes 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. 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.
Both classes served until 1957-1959.
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.
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 different boiler with thirty fewer tubes, but more superheat and a firebox with 65 sq ft (6 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.
Nineteen were sold to other railroads during World War Two. Thanks to Chris Hohl for his tabulation of the following transfers:
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.
Firebox had combustion chamber. Mallet compounds built in a total of 8 batches. The first in the series were five N&W-built Y-2s, built in 1918 and adopted by the USRA as the basis for their heavy articulated design. 50 Y-3 (USRA heavies) followed in 1919 and 30 more Y-3a were built in 1923.
The 10 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.
Later N&W engines were built to a larger design; see the Y-6 record.
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.
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, the 19 remaining Y-4as were rebuilt with cast-steel frames and cylinders. This fixed the wracking problem and the Y-5s, now virtually identical to the later Y-6s, served out steam on the Norfolk & Western.
Continuation of the N&W series of large Mallet compounds, the Y-5s were first introduced in 1930. Y-6 series engines had integrally cast cylinders in cast-steel frames, roller bearings on all axles, and piston valves as large as 18 inches in diameter.
HP piston valves measured 14" in diameter while the LP valves had an 18" bore. Heating surface data from N & W diagram book in Allen Stanley's large collection. 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 and the arch tubes by 41 sq ft while adding 100 sq ft of circulators.
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. All axles had Timken roller bearings and the valve gear used McGill multirol bearings.
The Y-6bs could divert live, high-pressure steam to the LP cylinders while working compound expansion. Pulling a load of 13,500 tons 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%). As 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 with a top speed of 50 mph -- 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..
|Specifications by Steve Llanso|
|Railroad||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)||Norfolk & Western (N&W)|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.28||0.27||0.27||0.27||0.27||0.27||0.27|
|Overall Wheelbase (engine & tender)||83.28'||101.02'||102.02'||98.23'||102.75'||103.85'||114.87'|
|Axle Loading (Maximum Weight per Axle)||60700 lbs|
|Weight on Drivers||360000 lbs||472000 lbs||485200 lbs||508500 lbs||522850 lbs||522850 lbs||548500 lbs|
|Engine Weight||390000 lbs||526000 lbs||539000 lbs||567000 lbs||582900 lbs||582900 lbs||611520 lbs|
|Tender Light Weight||170000 lbs||312700 lbs||312700 lbs||271200 lbs||378600 lbs||378600 lbs||378600 lbs|
|Total Engine and Tender Weight||560000 lbs||838700 lbs||851700 lbs||838200 lbs||961500 lbs||961500 lbs||990120 lbs|
|Tender Water Capacity||9000 gals||18000 gals||20000 gals||16000 gals||22000 gals||22000 gals||22000 gals|
|Tender Fuel Capacity (oil/coal)||14 tons||26 tons||26 tons||23 tons||30 tons||30 tons||30 tons|
|Minimum weight of rail (calculated) on which locomotive could run||75 lb/yard||98 lb/yard||101 lb/yard||106 lb/yard||109 lb/yard||109 lb/yard||114 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||200 psi||265 psi||270 psi||240 psi||300 psi||300 psi||300 psi|
|High Pressure Cylinders (dia x stroke)||24.5" x 30" (2)||24.5" x 32" (2)||25" x 32" (2)||25" x 32" (2)||25" x 32" (2)||25" x 32" (2)||25" x 32" (2)|
|Low Pressure Cylinders (dia x stroke)||39" x 30" (2)||39" x 32" (2)||39" x 32" (2)||39" x 32" (2)||39" x 32" (2)||39" x 32" (2)||39" x 32" (2)|
|Tractive Effort||78394 lbs||110797 lbs||114148 lbs||101465 lbs||126831 lbs||126831 lbs||126831 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.59||4.26||4.25||5.01||4.12||4.12||4.32|
|Firebox Area||210 sq. ft||468 sq. ft||453 sq. ft||426 sq. ft||430 sq. ft||430 sq. ft||555 sq. ft|
|Grate Area||75.20 sq. ft||96.30 sq. ft||96 sq. ft||96 sq. ft||106.20 sq. ft||106.20 sq. ft||106.20 sq. ft|
|Evaporative Heating Surface||5908 sq. ft||6308 sq. ft||5753 sq. ft||5932 sq. ft||5822 sq. ft||5647 sq. ft||4915 sq. ft|
|Superheating Surface||586 sq. ft||1567 sq. ft||1582 sq. ft||1582 sq. ft||1582 sq. ft||1775 sq. ft||1478 sq. ft|
|Combined Heating Surface||6494 sq. ft||7875 sq. ft||7335 sq. ft||7514 sq. ft||7404 sq. ft||7422 sq. ft||6393 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||360.92||361.27||316.44||326.28||320.23||310.61||270.34|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||15040||25520||25920||23040||31860||31860||31860|
|Same as above plus superheater percentage||16394||30623||31622||27878||38551||39506||39188|
|Same as above but substitute firebox area for grate area||45780||148824||149218||123710||156090||159960||204795|
After the Y4 class of 1927 demonstrated the effectiveness of the Worthington BL feedwater heater, the N&W modernized the Y3 and Y3a classes. They receive Worthington 4 1/2 BL feedwater heaters on the left side of the boiler and the air compressors were moved to the right side for balance. The engines also received N&W standard tenders of increased capacity ranging from 16,000 to 22,000 gallons and riding on Lewis six-wheel trucks. The smokebox front was modified with a larger round door carrying a circular number plate.
Other details were changed as well, until the most prominent remaining sign of the Y3's origins was the USRA-style cab. The Y3s served as the basis for the N&W's later and more famous 2-8-8-2 designs, including the ultimate Mallet class Y6b. By the time of World War II, the N&W had built enough of these more modern articulated to consider 19 Y3s surplus and they were sold to other railroad that were short of power. Thus six Y3s served on the Pennsylvania Railroad, five on the Union Pacific, and eight on the Atchison, Topeka & Santa Fe. In 1948 seven were sold to the Virginian Railway. They were reconditioned and put into service as the Virginian's USE class.
The World War II vintage Mallets worked out their last miles back in the coal fields and were ultimately scrapped in 1954 and 1955. The N&W's own remaining Y3s stayed in service until 1957-58, and the Y3as lasted until 1958-59.
In 1952, the Norfolk & Western ran several tests. These tests compared a four- unit F7 consist against a modified class A (2-6-6-4 number 1239) and later a modified class Y6b (2-8-8-2 number 2197). Several modifications were made to 2197 which made it different from the other Y6b locomotives. These modifications included a "booster valve", a new "intercepting/reducing valve" which increased its drawbar horsepower by 26% and its drawbar tractive effort by 15%. An article in the November 1991 issue of TRAINS titled N&W's Secret Weapons goes into more detail about these tests. The author of this article nicknamed the modified 2197 a "Y6c".
In the mid-1950s, when the older 2100 series locomotives were "shopped", they
were fitted with these same modifications. According to the author, these
retro-fitted "Ys" could now produce 170,000 pounds of tractive effort and 5,600
drawbar horsepower. Many consider these numbers to be erroneous.