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 Wheelbase (ft)10.33
Engine Wheelbase (ft)49.83
Ratio of driving wheelbase to overall engine wheebase 0.21
Overall Wheelbase (engine & tender) (ft)86.48
Axle Loading (Maximum Weight per Axle) (lbs)59,250
Weight on Drivers (lbs)356,500
Engine Weight (lbs)429,500
Tender Light Weight (lbs)212,660
Total Engine and Tender Weight (lbs)642,160
Tender Water Capacity (gals)12,000
Tender Fuel Capacity (oil/coal) (gals/tons)4000
Minimum weight of rail (calculated) (lb/yd)99
Geometry Relating to Tractive Effort
Driver Diameter (in)57
Boiler Pressure (psi)200
High Pressure Cylinders (dia x stroke) (in)23.5" x 32"
Low Pressure Cylinders (dia x stroke) (in)37" x 32"
Tractive Effort (lbs)75,112
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.75
Heating Ability
Firebox Area (sq ft)444
Grate Area (sq ft)72.20
Evaporative Heating Surface (sq ft)4936
Superheating Surface (sq ft)1051
Combined Heating Surface (sq ft)5987
Evaporative Heating Surface/Cylinder Volume307.27
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation14,440
Same as above plus superheater percentage17,039
Same as above but substitute firebox area for grate area104,784
Power L17927
Power MT294.13


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