Class D1A (Locobase 5435) 
Data from a table in January 1917 RME and DeGolyer, Vol 55, pp.137+ See Locobase 7655 for a later upgrade of this design. 43950-43951, 43994-43997 in August 1916; 44100-44104, 44134-44136, 44156-44157 in September; 44205-44206 in October; 44207-44208 in November
This very large Santa Fe greatly increased the B & LE's hauling power. Much of the data is similar to that of the CB&Q and C & IM engines of contemporary vintage and builder. Locobase notes the enormous quantity of flexible stays such a large, mobile coal furnace required: "1,000 in number ...four top horizontal rows of each outside side sheet, in throat sheet throughout, in back head, throughout except at fire door frame. Three vertical rows at each end of side sheet diagonally across (at ends of side sheets from said horizontal rows to said vertical rows." The combustion chamber was braced by 380 additional flexible stays.
Firebox heating surface included 129 sq ft (12 sq m) in the combustion chamber and 43 sq ft (4 sq m) from five arch tubes. Fifteen-inch (381 mm) piston valves served for steam admission. The trailed cylindrical Vanderbilt tenders.
Relatively high-drivered for their arrangement, the class lasted until the end of steam and entered retirement in 1948-1951.
Class D1A - syphons (Locobase 7655)
Data from B&LE 1 - 1944 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.
Although the B&LE liked its Santa Fes as they came off the production line (Locobase 5435), the design wasn't allowed to stand completely still. Later modifications included a large combustion chamber that contributed 129 sq ft to total firebox heating surface. In addition, 3 thermic syphons added 99 sq ft of direct heating surface; two of these served the firebox, one the combustion chamber. The firebox also retained its 27 sq ft of arch tubes.
Perhaps one reason the B & LE liked these Santa Fes better than those designed by the USRA (See Locobase 9030) was the provision of 16" piston valves and Baker valve gear. They also put 20 more tons of adhesive weight on the rails than did the USRAs. In any event, most of the class saw steam out on the B & LE.
Class D2A (Locobase 9030)
Data from B&LE 1 - 1944 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.
Although the quintet of engines from Baldwin were USRA Santa Fes when they came on the road, later modifications added considerably to their direct heating surface. A similar program was applied to the D1As (this modification is described in Locobase 7655).
The 104 sq ft combustion chamber received one of 3 thermic syphons; the other two were placed in the cavernous firebox, which retained its 27 sq ft of arch tubes. All three thermic syphons contributed 110 sq ft of firebox heating surface. 14" piston valves actuated by Southern valve gear let the steam into the cylinders.
Drury (1993) comments that these engines weren't as well liked as the pre-Great War D1As and were retired before those engines were withdrawn. (There were 4 times as many of the D1As, which may have had something to do with it.)
