Norfolk and Western Y3 class

The Norfolk and Western Y3 Class was a class of 2-8-8-2 "Mallet" articulated steam locomotives with a total of 80 locomotives built for the Norfolk and Western Railway between 1919 and 1923.

Development
In March 1918, the Norfolk and Western Railway (N&W), which had been experimenting with Mallet locomotives to satisfy their growing mainline coal traffic over the Blue Ridge Mountains, introduced Y2 class 2-8-8-2 No. 1700, which was constructed at the Railway's shops in Roanoke, Virginia. When No. 1700 was placed into service, it was quickly deemed a success, being able to produce 135,600 lbf of tractive effort with simple expansion, and 104,300 lbf with compound expansion, but the locomotive's flawed boiler and firebox design prevented it from producing enough required steam.

During this time, the United States Railroad Administration (USRA), which was created to control and standardize North American railroads during World War I, assigned the N&W, the Virginian Railway, and the Chesapeake and Ohio Railway (C&O) to their Pocahontas Region, with N&W president Nicholas D. Mahler serving as the regional manager. The USRA’s mechanical engineering committee, which included two staff members from the N&W's engineering team, used the N&W's Y2 prototype as the basis for the USRA's standard 2-8-8-2 design, with the boiler and firebox problems being solved.

Construction and design
The USRA 2-8-8-2's were designed with 25x32 in high-pressure cylinders, 36x32 in low-pressure cylinders, 57 in diameter driving wheels, and a working boiler pressure of 240 psi, and they were able to generate a tractive effort of 106,000 lbf with compound expansion. A Mellin-type by-pass and intercepting control valve was used to transition the locomotive between simple and compound operations. Other features the USRA design came with included the Type A Schmidt Superheater, the N&W-style short frame Baker valve gear, and smokebox-mounted air pumps.

Their tenders originally carried 16 ST of coal and 12,000 gal of water. The N&W received forty-five locomotives (Nos. 2000-2044) of the USRA design in February, April, and May of 1919 from the American Locomotive Company's (ALCO) Schenectady Works, and the railway classified them as Y3's.  Five more Y3's (Nos. 2045-2049) were delivered from the Baldwin Locomotive Works in August and September that same year. While the N&W was also allowed to continue ordering 1700 series Y2 class locomotives, the N&W was satisfied with the Y3's superior performance, since they were able to travel with more reliable counterbalancing.

Between March and June of 1923, three years the N&W was released from USRA control, the N&W decided to order thirty copies of the USRA 2-8-8-2's from ALCO's Richmond, Virginia Works, and they were classified as Y3a's (Nos. 2050-2079). Towards the end of the 1920s, the N&W began rebuilding and modifying all their Y3's and Y3a's; their air pumps were moved to the right ride of the boiler; they were equipped with a Worthington BL feedwater heater on the left side; and their boiler pressure was raised to 270 psi, resulting in their tractive effort being boosted to 136,985 lbf with simple expansion and 114,154 lbf with compound expansion. Their tenders were replaced with larger ones that carried 30 ST of coal and 22,000 gal of water.

Revenue service and retirement
When the Y3's were first placed into service in 1919, they were assigned alongside the Y2's in pulling the N&W's heavy coal trains over their steep grades. Throughout the 1920s and 1930s, the Y3's and Y3a's were assigned in general freight service on all the N&W's mainlines and branch lines. Some Y3's were also used alongside the Y2's as switchers at their coal classification yards, such as the East Portsmouth, Ohio yard. One Y3, No. 2006, was modified with a booster called a "Bethlehem Auxiliary Locomotive", which consisted of two powered trucks beneath the tender, and it increased the locomotive's tractive effort by 34,500 lbf, allowing for more efficient switching maneuvers.

Towards their final years in service, the Y3's replaced the Z1 class 2-6-6-2's in pulling 10,000 ST coal trains from Crewe to Roanoke. In June 1956, No. 2003 became the first Y3 to be retired from the N&W and sold for scrap, and within the next two years, the rest of the Y3's were also withdrawn from service, as the N&W began to dieselize their roster. Most of the Y3a's followed suit in 1958 and 1959.

Usage on other railroads
During World War II, the N&W sold several of their surplus steam locomotives, including seventeen Y2's, nineteen Y3's, and all the K3 class 4-8-2's, to other railroads in need of extra motive power to help assist the wartime shipments. In particular, six Y3's were sold in May 1943 to the Pennsylvania Railroad (PRR), which held a 30% share in N&W's stock at the time. The PRR reclassified their Y3's as HH1's, renumbered them as Nos. 373-378, and assigned them to operate out of their mainline terminal in Enola, Pennsylvania and on their Harrisburg—Hagerstown branch.

Throughout 1943, eight other Y3's were sold to the Atchison, Topeka and Santa Fe Railroad, where they were renumbered as Nos. 1790-1797. The Santa Fe assigned the eight 2-8-8-2's to operate on Raton Pass, where they helped push heavy freight trains up the Raton grade, and they sometimes assisted 4-8-4's in pulling longer passenger consists. The railroad quickly became ambivalent to Nos. 1790-1797's performances; while they were able to assist longer trains at Raton Pass, the locomotives' slow speeds made them incompatible with the Santa Fe's fast-moving operations. In December 1947, the Santa Fe sold Nos. 1790-1796 to the Virginian Railway, where they were renumbered again as Nos. 736-742, reclassified as USE's, and rebuilt at their Princeton, West Virginia shops. The Virginian purchased the former Y3's to replace their aging 2-10-10-2's, and the USE's were assigned to pull the railway's heavy coal trains over the Clark's Gap ruling grade. When the Virginian acquired diesel locomotives from Fairbanks-Morse in 1954, all the USE's were retired from the roster.

In June 1945, the N&W sold five more Y3's to the Union Pacific Railroad (UP), where they were renumbered as Nos. 3670-3674. The UP assigned their five 2-8-8-2's to operate around Green River and Rock Springs, Wyoming, and while they were shown to be successful in stop gap purposes, they were quickly deemed surplus, since the UP's 4-6-6-4 "Challengers" and 4-8-8-4 "Big Boys" were more powerful and reliable. Nos. 3670-3674 were all scrapped in 1948.

Preservation
Only one of the Y3a's, No. 2050, has been preserved. In 1958 and 1959, several Y3a's were sold for scrap to the Armco Steel Corporation in Middletown, Ohio, but No. 2050 was one of three such locomotives that Armco chose at random to be used as stationary boilers. The other two Y3a's were eventually scrapped, but No. 2050 remained in outdoor storage until 1975, when it was donated to the Illinois Railway Museum (IRM), and the following year, it was moved to the museum's property in Union, Illinois for static display.

N&W Y3b/Y4 class
In January 1927, the N&W received ten more copies (Nos. 2080-2089) of the USRA 2-8-8-2's from ALCO's Richmond Works. The ten mallets, along with some Southern Railway Ps-4 class 4-6-2's, were the very last locomotives to be built at the Richmond plant before ALCO shut it down, and they were the very last steam locomotives the N&W ordered from an outside manufacturer; every future steam locomotive the railway ordered would be built at their Roanoke shops. Nos. 2080-2089 were classified as Y3b's, since they were heavier at 567,000 lb and came with some different design features from the Y3's and Y3a's; their air compressors were always mounted on the left side of the boiler; they were built with Worthington BL feedwater heaters; and their tenders held different capacities—23 ST of coal and 16,000 gal of water.

In October 1927, the Y3b's were all reclassified as Y4's, and in later years, they received some modifications to improve their performances; their boiler pressure was boosted from 240 psi to 270 psi; their driving wheel diameter was increased from 57 in to 58 in; and they received larger tenders that carried 26 ST of coal and 18,000 gal of water. In 1953, the Y4s' tender capacity was further boosted to 27 ST of coal and 24,000 gal of water, when the locomotives received eight-axle tenders formerly paired with Atlantic Coast Line R-1 class 4-8-4's. The Y4 locomotives were assigned in general freight and mine switching service alongside the older Y3's, but all of them were retired and scrapped in 1958.