Virginian 2-8-8-0 "Consolidation Mallet" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Triplex reborn - AF (Locobase 3566)

Data from VGN 8 - 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 68, pp. 377+. Works number was 55100 in September 1921.

After the 2-8-8-8-4 Triplex had proved a flat-footed failure (Locobase 3301), Baldwin took the huge boiler and placed it on a 2-8-8-0 engine unit. The cylinders matched those of the 1913 ADs, but the tube and flue layout remained that of the Triplex boiler. Firebox heating surface included 72 sq ft (6.7 sq m) of arch tubes. The firebox also had a Gaines combustion chamber and was fed by a Duplex automatic stoker. (For a full description of the Gaines combustion chamber's intended effect on combustion, see Locobase 4228.) The resulting combination of boiler and superheater put the AF in a very small class of steam locomotives with over 10,000 sq ft (929 sq m) of combined heating surface.

The high-pressure cylinders powering the rear driver set were fed by 16" (406 mm) piston valves while the low-pressure cylinders under the smokebox were supplied by Allen-Richardson balanced slide valves.

The ruling grade for AF service was the 12 mile (19.3 km) portion of the Elmore to Clark's Gap segment that inclined at 2.07%. The single AF gained a trailing truck in November 1942 to become a 2-8-8-2 and operated until 1953.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassTriplex reborn - AF
Locobase ID3566
RailroadVirginian (VGN)
Number in Class1
Road Numbers610
Number Built1
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)15.25 / 4.65
Engine Wheelbase (ft / m)50.50 / 15.39
Ratio of driving wheelbase to overall engine wheebase 0.30
Overall Wheelbase (engine & tender) (ft / m)90.92 / 27.71
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)487,400 / 221,081
Engine Weight (lbs / kg)526,190 / 238,676
Tender Loaded Weight (lbs / kg)235,000 / 106,594
Total Engine and Tender Weight (lbs / kg)761,190 / 345,270
Tender Water Capacity (gals / ML)13,000 / 49.24
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)102 / 51
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)56 / 1422
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)28" x 32" / 711x813
Low Pressure Cylinders (dia x stroke) (in / mm)44" x 32" / 1118x813
Tractive Effort (lbs / kg)108,416 / 49176.73
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.50
Heating Ability
Firebox Area (sq ft / m2)430 / 39.96
Grate Area (sq ft / m2)108.20 / 10.06
Evaporative Heating Surface (sq ft / m2)8120 / 754.65
Superheating Surface (sq ft / m2)2059 / 191.36
Combined Heating Surface (sq ft / m2)10,179 / 946.01
Evaporative Heating Surface/Cylinder Volume356.05
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation21,640
Same as above plus superheater percentage25,968
Same as above but substitute firebox area for grate area103,200
Power L19546
Power MT345.43

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Wes Barris