Wabash 4-6-4 "Hudson" Locomotives in the USA

The Wabash Railroad, in need of passenger locomotives during World War II, coverted five of its older Class K-5 "Mikados" into 4-6-4s. These new locomotives, designated Class P-1 (road numbers 700 through 704), were rebuilt in the Decatur Shops during 1943 and 1944.

The five K-5s used to build these "Hudsons" were bought from the American Locomotive Company in 1925 and were the only three-cylinder 2-8-2s on the Wabash.

Later, in 1946 and 1947, a pair of the two cylinder Class K-5s were also converted into "Hudsons" and were assigned road numbers 705 and 706.

All seven of the Class P-1 "Hudsons" were scrapped in 1956.

Class Details by Steve Llanso of Sweat House Media

Class P1 (Locobase 189)

Data from WAB 1 - 1946 Locomotive, Crane, and Marine Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Collection. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error .)

Five of these locomotives were rebuilt by the Wabash in 1943 from K-5 class 2-8-2 engines originally built by Alco in 1925 (Locobase 23). Two more followed after World War II, but were derived from earlier K-4s. The engines gave up their center cylinder and a driving axle, had larger drivers, and were fitted with Timken roller bearings. 12" (305 mm) piston valves supplied steam to the cylinders. The firebox heating surface included 32 sq ft (2.97 sq m) of arch tubes.

The engines were semi-streamlined with long "elephant ears" and given a light blue paint scheme with a broad white stripe along the running boards; the tenders received a similar paint job.

They ran until 1956.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID189
Number in Class7
Road Numbers700-706
Number Built7
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14 / 4.27
Engine Wheelbase (ft / m)40.58 / 12.37
Ratio of driving wheelbase to overall engine wheebase 0.34
Overall Wheelbase (engine & tender) (ft / m)75.46 / 23
Axle Loading (Maximum Weight per Axle) (lbs / kg)65,570 / 29,742
Weight on Drivers (lbs / kg)196,390 / 89,081
Engine Weight (lbs / kg)374,680 / 169,952
Tender Loaded Weight (lbs / kg)208,000 / 94,347
Total Engine and Tender Weight (lbs / kg)582,680 / 264,299
Tender Water Capacity (gals / ML)12,000 / 45.45
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)16 / 14.50
Minimum weight of rail (calculated) (lb/yd / kg/m)109 / 54.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)80 / 2032
Boiler Pressure (psi / kPa)220 / 15.20
High Pressure Cylinders (dia x stroke) (in / mm)26" x 28" / 660x711
Tractive Effort (lbs / kg)44,244 / 20068.76
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.44
Heating Ability
Firebox Area (sq ft / m2)341 / 31.69
Grate Area (sq ft / m2)71 / 6.60
Evaporative Heating Surface (sq ft / m2)4225 / 392.66
Superheating Surface (sq ft / m2)1051 / 97.68
Combined Heating Surface (sq ft / m2)5276 / 490.34
Evaporative Heating Surface/Cylinder Volume245.55
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,620
Same as above plus superheater percentage18,744
Same as above but substitute firebox area for grate area90,024
Power L126,236
Power MT883.55

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