Spokane, Portland & Seattle 4-6-2 "Pacific" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class H-1 (Locobase 8846)

Data from SP&S 2 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Originally delivered to the SP & S as redirected E-14 Ten-wheelers from the Great Northern (one of two SP & S owners), these engines underwent signficant changes in the 1920s. The design followed that of the Great Northern's H-5/H-7 rebuild (Locobase 6450). Total heating surface in the boiler remained about the same, but the percentage of superheater area rose considerably. Also, the boiler was lengthened by 42" and the Belpaire firebox gained a combustion chamber.

Specifications by Steve Llanso of Sweat House Media
Locobase ID8846
RailroadSpokane, Portland & Seattle
Number in Class6
Road Numbers620-625
Number Built
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase13.50'
Engine Wheelbase36.96'
Ratio of driving wheelbase to overall engine wheebase 0.37
Overall Wheelbase (engine & tender)75.11'
Axle Loading (Maximum Weight per Axle)55500 lbs
Weight on Drivers166500 lbs
Engine Weight283400 lbs
Tender Light Weight252700 lbs
Total Engine and Tender Weight536100 lbs
Tender Water Capacity18000 gals
Tender Fuel Capacity (oil/coal)4950 gals
Minimum weight of rail (calculated)93 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"
Boiler Pressure210 psi
Cylinders (dia x stroke)23.5" x 30"
Tractive Effort40511 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.11
Heating Ability
Firebox Area272 sq. ft
Grate Area55 sq. ft
Evaporative Heating Surface3157 sq. ft
Superheating Surface774 sq. ft
Combined Heating Surface3931 sq. ft
Evaporative Heating Surface/Cylinder Volume209.62
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation11550
Same as above plus superheater percentage13860
Same as above but substitute firebox area for grate area68544
Power L119481
Power MT773.84


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