Seaboard Air Line 2-6-6-4 Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class R-1 (Locobase 302)

Data from tables and diagrams in 1947 Locomotive Cyclopedia and from from the 1948 SAL locomotive diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "Seaboard Air Line Buys Five Locomotives", Baldwin Locomotive Magazine, Volume 14, No 1 (April 1935), p. Works numbers ran 61829-61833.

In addition to the long combustion chamber, the firebox heating surface area included two Nicholson thermic syphons as well as 19 sq ft (1.77 sq m) of arch tubes. See Trains Magazine (August 1979) for an account of how these engines ran. They were well-liked with many engineers feeling that they were capable of higher speeds than the road would let them reach.

See Locobase 10077 for the later batch of R-2s, which had slightly different specs.


Class R-2 (Locobase 10077)

Data from tables and diagrams in 1947 Locomotive Cyclopedia and from from the 1948 SAL locomotive diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange..

These R-2s (works numbers 62054-62058) had slightly fewer tubes than the earlier R-1, a cleaner-looking Walschaerts valve motion, single crosshead guides, and Elesco feedwater heaters replaced by Worthingtons, but otherwise varied little from the earlier R-1s.

These engines later (1947) went on to the B&O as KB-1 and KB-1a 7700-7709, where the slip joints in the piping to the front engine unit (which leaked frequently) were replaced by ball joints. They were slippery on grades and not as well liked as the Big Sixes (2-10-2), although a later relocation of the air pumps to the pilot on one engine reduced the slipping.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassR-1R-2
Locobase ID302 10,077
RailroadSeaboard Air Line (SAL)Seaboard Air Line (SAL)
CountryUSAUSA
Whyte2-6-6-42-6-6-4
Number in Class55
Road Numbers2500-25042505-2509
GaugeStdStd
Number Built55
BuilderBaldwinBaldwin
Year19351937
Valve GearBakerWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6612 / 3.66
Engine Wheelbase (ft / m)67.42 / 20.5567.42 / 20.55
Ratio of driving wheelbase to overall engine wheebase 0.18 0.18
Overall Wheelbase (engine & tender) (ft / m)97.75 / 29.7997.75 / 29.79
Axle Loading (Maximum Weight per Axle) (lbs / kg)55,000 / 24,94855,000 / 24,948
Weight on Drivers (lbs / kg)330,000 / 149,686330,000 / 149,686
Engine Weight (lbs / kg)480,000 / 217,725480,000 / 217,725
Tender Loaded Weight (lbs / kg)310,200 / 140,705310,200 / 140,705
Total Engine and Tender Weight (lbs / kg)790,200 / 358,430790,200 / 358,430
Tender Water Capacity (gals / ML)16,000 / 60.6116,000 / 60.61
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)24 / 21.8024 / 21.80
Minimum weight of rail (calculated) (lb/yd / kg/m)92 / 4692 / 46
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175369 / 1753
Boiler Pressure (psi / kPa)230 / 15.90230 / 15.90
High Pressure Cylinders (dia x stroke) (in / mm)22" x 30" / 559x762 (4)22" x 30" / 559x762 (4)
Tractive Effort (lbs / kg)82,280 / 37321.6282,280 / 37321.62
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.01 4.01
Heating Ability
Firebox Area (sq ft / m2)515 / 47.96515 / 47.86
Grate Area (sq ft / m2)96.30 / 8.9596.30 / 8.95
Evaporative Heating Surface (sq ft / m2)5513 / 512.365429 / 504.55
Superheating Surface (sq ft / m2)2397 / 222.772397 / 222.77
Combined Heating Surface (sq ft / m2)7910 / 735.137826 / 727.32
Evaporative Heating Surface/Cylinder Volume208.84205.66
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation22,14922,149
Same as above plus superheater percentage28,79429,015
Same as above but substitute firebox area for grate area153,985155,170
Power L129,71929,635
Power MT1191.261187.89

Reference