2-6-6-2 "Mallet Mogul" Steam Locomotives in the USA

Class 340/L-62 (Locobase 16364)

Data from Lionel Wiener, "Note sur les locomotives articulees", Extrait from Revue Generale des Chemins de fer et des Tramways, (May and June, 1913), Tableau Q, p. 93.Works numbers were 46717-46724 in January 1910.

Eight Mallet compounds for helper service in Soldier Pass and Tennessee Pass. Firebox heating surface area included 40 sq ft (3.72 sq m) of combustion chamber. George Drury noted that introducing these big engines eliminated the need for quintuple-heading DR&G freights.

Later renumbered 3300-3307. Retired in 1947-1952.

Class 340/L-62 (Locobase 294)

Data from D&RGW 1956 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for 3 April 2020 email correcting engine wheelbases, boiler pressure, and tender water capacity.)

Eight Mallet compounds for helper service in Soldier Pass and Tennessee Pass. They were delivered as saturated-steam locomotives described in Locobase 16364. As shown in the specs, however, they were later superheated.

The usual exchange of small tubes for larger flues dropped the total evaporative heating surface area both because of the lower number but the smaller diameter (2" vs 2 1/4" in the original boiler) of each tube. They retained the short combustion chamber that contributed 40 sq ft (3.72 sq m) to the firebox heating surface area and the mixture of 10" (254 mm) piston valves for the HP cylinders and slide valves for the LP cylinders. The updated HP cylinders gained 1/2" (12.7 mm) in diameter.

Retired in 1947-1952.