Western Pacific 2-6-6-2 Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class M-80 (Locobase 3101)

Firebox heating surface originally included 26 sq ft of arch tubes and amounted to 386 sq ft. The later heating surface value shown in the specs included 84 sq ft of thermic syphons.

Frank Brehm's roster at http://www.wplives.com/motivepower/srosters/Class_201_Roster__/class_201_roster__.html (accessed 3 July 2006) gives details of the class: Five were built by Brooks in 1917 (works #57444-57448) for $52,861 each and 5 more came from Richmond in 1924 (works# 65485-65489). Wartime inflation had taken its toll, however -- unit price for this quintet was $83,405.

They originally took on the Feather River Canyon run between Oroville and Portola, Calif. M-137 s, which could take singly trains that required an M-80 and an MK-60 together, replaced the M-80s in 1931. They then ran over the Northern California Extension between Keddie and Bieber until the end of steam.

Specifications by Steve Llanso of Sweat House Media
Locobase ID3101
RailroadWestern Pacific (WP)
Number in Class10
Road Numbers201-210
Number Built10
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase10.33'
Engine Wheelbase49.83'
Ratio of driving wheelbase to overall engine wheebase 0.21
Overall Wheelbase (engine & tender)86.48'
Axle Loading (Maximum Weight per Axle)59250 lbs
Weight on Drivers356500 lbs
Engine Weight429500 lbs
Tender Light Weight212660 lbs
Total Engine and Tender Weight642160 lbs
Tender Water Capacity12000 gals
Tender Fuel Capacity (oil/coal)4000 gals
Minimum weight of rail (calculated)99 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter57"
Boiler Pressure200 psi
High Pressure Cylinders (dia x stroke)23.5" x 32"
Low Pressure Cylinders (dia x stroke)37" x 32" (2)
Tractive Effort75112 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.75
Heating Ability
Firebox Area444 sq. ft
Grate Area72.20 sq. ft
Evaporative Heating Surface4936 sq. ft
Superheating Surface1051 sq. ft
Combined Heating Surface5987 sq. ft
Evaporative Heating Surface/Cylinder Volume307.27
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation14440
Same as above plus superheater percentage17039
Same as above but substitute firebox area for grate area104784
Power L17927
Power MT294.13


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