Virginian 2-8-8-8-2/4 "Triplex" Locomotives in the USA

Class XA (Locobase 3301)

Data from DeGolyer, Volume 55, pp. 187+. See also "Triple Articulated Compound Locomotive for the Virginian Railway,", Railway and Locomotive Engineering, Volume 30, No. 3 (March 1917), pp. 73-76; and "Virginian Railway has World's Greatest Steam Locomotive," Engineering News, Volume 77, No. 11 (15 March 1917), pp 417-418. (Thanks to Peter Christener for his 22 June 2016 email correcting the design's designation and to Chris Hohl's 29 October 2016 email noting the improbable tender capacity Locobase had mistakenly entered.) Baldwin works number was 44448 in November 1916.

Like the Erie's Triplex 2-8-8-8-2s, this single locomotive showed all the limitations of trying to cram so much tractive power under one boiler.

Although this design had slightly smaller cylinders under a slightly larger boiler, the grate and evaporative heating surface were still too small. The small firebox gained some additional direct heating surface from the 72 sq ft (6.7 sq m) in five arch tubes supporting the brick arch. A Gaines type combustion chamber was located ahead of the half-height Gaines wall in the firebox. Although Baldwin's detailed specs don't state the chamber's length, the firebox measured 15 ft 8 in (4.775 m) long and the grate 12 ft (3.658 m).. Locobase uses the difference to approximate the Gaines combustion chamber's length. The firebox's high fuel demand was fed through a Street stoker.

(For a full description of the Gaines combustion chamber's intended effect on combustion, see Locobase 4228.)

Baldwin feed water heater contained 437 sq ft (40.6 sq m). All six cylinders admitted steam through 14-inch (356 mm) piston valves.

The specifications included the requirement that the engine drag 2,580 tons (2,345 metric tons) of cars and leading from Elmore to Clark's Gap over 14 miles (22.5 km) of track of which 12 miles (19.3 km) ascended at 2.07% and wound around ten 12-degree curves. Four-fifths of the load (2,064 tons or 1,876 metric tons) were to go up the grade at 10 mph (16 km/h).

Drury (1993) notes that compared to the Erie engines, the 700 "was slower and ran out of steam faster[!]..." He adds that one tunnel had only four inches of clearance, which must have made a passage hell on earth for the locomotive and its crew. "It never made a successful trip," according to Drury.

The engine units were turned into a 2-8-8-0 Mallet (Locobase 3566) and a 2-8-2 Mikado (Locobase 7486), each of which ran until 1953.