Baltimore & Ohio / Buffalo, Rochester, & Pittsburgh 2-6-6-2 Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class KK-1 (Locobase 3099)

Like the T-1/T-2 4-8-2 comparison, the KKs were built in single copies to compare the Emerson watertube firebox to a conventional locomotive. This was the EWT entry, works number 61571 in November 1930.

These are the only 2-6-6-2 articulateds the B&O operated other than the BR&P KK-1s (Locobase 295) and are almost unknown today. This engine was converted briefly to a 4-4-6-2 arrangement for passenger service, but soon was restored as a Prairie Mallet and lasted until 1953.

Class KK-2 (Locobase 296)

Data from B&O to 1954 Assorted Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Works number was 61560 in November 1930.

The 7450 with the conventional stayed firebox was built to compare to the 7400 (Locobase 3099) with an Emerson watertube firebox. In addition to 110 sq ft (10.2 sq m) of heating surface in the combustion chamber, this engine's firebox heating surface at first included 46 sq ft (4.25 sq m) of arch tubes, but the appliance contribution was later revamped with 18 sq ft (1.65 sq m) of arch tubes and 95 sq ft (8.8 sq m) of thermic syphons for a total of 403 sq ft (37.45 sq m).

Class LL / KK-4 (Locobase 295)

Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). Data confirmed by table in May 1916 RME and BR&P 11 - 1930 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. (Thanks to Chris Hohl for pointing out the valve gear IDs on the subclasses.)

These 55 locomotives were built at Alco's Schenectady and Brooks works from 1914 to 1923. All were delivered with 14" (356 mm) piston valves serving the HP cylinders and slide valves supplying the LP cylinders. All but the 7526-7540 batch from Brooks used Walschaert's valve gear. That set of fifteen was equipped with Southern gear.

Several batches delivered as follows, as classified by the B&O and renumbered in 1932:

Works numbers

KK-4 7500-7504 Schenectady 1914 54702-54706

KK-4a 7505-7509 Brooks 1917 57209-57213

KK-4b 7510-7525 Brooks 1918 57996-58011

KK-4c 7526-7540 Brooks 1918 58479-58493

KK-4d 7541-7554 Brooks 1923 64603-64616

One was rebuilt as KK-5 in 1949 with chassis lubrication, bed casting

Retired by 1951.

Specifications by Steve Llanso of Sweat House Media
ClassKK-1KK-2LL / KK-4
Locobase ID3099 296 295
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Buffalo, Rochester, & Pittsburgh (B&O)
Number in Class1155
Road Numbers74007450700-754 / 7500-7554
Number Built1155
Valve GearWalschaertWalschaertWalschaert or Sthrn
Locomotive Length and Weight
Driver Wheelbase34.92'12.17'10.33'
Engine Wheelbase56'55.67'49.66'
Ratio of driving wheelbase to overall engine wheebase 0.62 0.22 0.21
Overall Wheelbase (engine & tender)104.41'86.48'
Axle Loading (Maximum Weight per Axle)68000 lbs
Weight on Drivers372000 lbs373000 lbs367500 lbs
Engine Weight465000 lbs466000 lbs445000 lbs
Tender Light Weight273000 lbs273000 lbs205600 lbs
Total Engine and Tender Weight738000 lbs739000 lbs650600 lbs
Tender Water Capacity18000 gals18000 gals12000 gals
Tender Fuel Capacity (oil/coal)20 tons20 tons14 tons
Minimum weight of rail (calculated)103 lb/yard104 lb/yard102 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter70"70"57"
Boiler Pressure250 psi250 psi200 psi
High Pressure Cylinders (dia x stroke)23" x 30"23" x 30"23.5" x 32"
Low Pressure Cylinders (dia x stroke)37" x 32" (2)
Tractive Effort96354 lbs96354 lbs75112 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.86 3.87 4.89
Heating Ability
Firebox Area866 sq. ft432 sq. ft388 sq. ft
Grate Area92 sq. ft92.30 sq. ft72.20 sq. ft
Evaporative Heating Surface6543 sq. ft5471 sq. ft4935 sq. ft
Superheating Surface1666 sq. ft1698 sq. ft1046 sq. ft
Combined Heating Surface8209 sq. ft7169 sq. ft5981 sq. ft
Evaporative Heating Surface/Cylinder Volume226.77189.62307.20
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation230002307514440
Same as above plus superheater percentage276002861316895
Same as above but substitute firebox area for grate area25980013392090792
Power L126149231637772
Power MT929.82821.43279.74


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