USRA 2-6-6-2

The USRA 2-6-6-2 was a standardized design of 2-6-6-2 Mallet locomotives developed by the United States Railroad Administration during World War I.

Design

The USRA 2-6-6-2 locomotive was a Mallet, or compound articulated type, having both low-pressure and high-pressure cylinders. The smaller high-pressure cylinders powered the rear set of driving wheels, and the larger low-pressure cylinders powered the forward set of driving wheels. The USRA 2-6-6-2 articulated locomotives were direct developments of the Chesapeake & Ohio class H2 and H4 series.

Orders

During the tenure of the USRA, 30 of these articulated steam locomotives were built. The Chesapeake and Ohio Railway (C&O) and Wheeling and Lake Erie Railroad (W&LE) ordered the USRA 2-6-6-2 Mallet. The first Mallet was delivered to the W&LE in 1919 for $71,966.94. Later, the Nickel Plate Road (NKP) leased them from the W&LE, renumbering them for use on its rails. With two independently swiveling driver and truck mechanisms (which is also used on modern diesel locomotives), this limber giant’s unique design allowed it to negotiate branch lines and tight curves while hauling larger consists than its smaller cousins in the USRA series.

The Chesapeake & Ohio Railroad ordered the first of these compact USRA 2-6-6-2 steam locomotives from Alco in 1911. It was a massive locomotive for the time, and it performed well enough for the C&O to order additional, but slightly modified, versions right through 1923. These locomotives were designed to replace the 2-8-0 Consolidations for the coal drags on the C&O’s Hinton Division. The 2-6-6-2s could handle more tonnage than the double-headed pair of 2-8-0s they replaced, and they burned less coal in the process. The 2-6-6-2s proved to be ideal mine run engines as their power and flexibility plus low weight on drivers made them ideal for the curving and heavily graded branches in the mountains of Virginia and West Virginia.

An additional ten (10) locomotives were built in 1949. These C&O Class H6 2-6-6-2s, numbered 1300 to 1309, were the last steam locomotives produced by Baldwin for use in the United States. The last of these were retired in 1957. Most of the locomotives were scrapped, but, the last two produced were retained by C&O as examples of their steam heritage. The 1308 is in the care of the Collis P. Huntingdon Chapter of the National Railway Historical Society [http://www.newrivertrain.com] at Huntington, West Virginia, while the 1309 is in the Baltimore and Ohio Railroad Museum, at Baltimore, Maryland.

Specifications

USRA 2-6-6-2 locomotives built from 1911 to about 1940:
* Drivers: 56¼" (1.43 m)
* Cylinders: 22" & 35" X 32"
* Total engine weight: 449,000 lb (203,700 kg)
* Weight on drivers: 376,500 lb (170,800 kg)
* Boiler pressure: 210 psi (1.45 MPa)
* Tractive effort: 77,900 lbf (347 kN)

USRA 2-6-6-2 locomotives built in 1949:
* Drivers: 56" (1.42 m)
* Cylinders: 22" & 35" X 32"
* Total engine weight: 434,900 lb (197,300 kg)
* Weight on drivers: 366,700 lb (166,300 kg)
* Boiler pressure: 210 psi (1.45 MPa)
* Tractive effort: 77,900 lb (347 kN)