Western Pacific 4-6-6-4 "Challenger" Type Locomotives

Class M-100 (Locobase 343)

Data from 1947 Locomotive Cyclopedia. Roster information from Frank Brehm's compilation hosted at http://www.wplives.com/motivepower/srosters/Class_407_Roster__/class_401-407_roster__.html (accessed 3 July 2006). Alco works# 68902-68908, each of these engines cost $181,762 on delivery. Fourteen years later, scrap value amounted to $13,762.

Little-remarked group of Challengers for the WP that ran across the desert from Elko, Nevada to Salt Lake City, Utah. Four thermic syphons contributed 132 sq ft to the direct heating surface. Very similar to the Clinchfield and D&H locomotives running on this wheel arrangement. Supplanted by diesels in 1950.

Specifications
ClassM-100
Locobase ID343
RailroadWestern Pacific (WP)
Whyte4-6-6-4
Road Numbers401-407
GaugeStd
BuilderAlco
Year1943
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase12.17'
Engine Wheelbase59.92'
Ratio of driving wheelbase to overall engine wheebase 0.20
Overall Wheelbase (engine & tender)106.54'
Axle Loading (Maximum Weight per Axle)66500 lbs
Weight on Drivers399000 lbs
Engine Weight590000 lbs
Tender Light Weight401500 lbs
Total Engine and Tender Weight991500 lbs
Tender Water Capacity22000 gals
Tender Fuel Capacity (oil/coal)25 tons
Minimum weight per yard of rail on which locomotive could run110.83 lb rail
Geometry Relating to Tractive Effort
Driver Diameter70"
Boiler Pressure265 psi
Cylinders (dia x stroke)22" x 32" (4)
Tractive Effort99676 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.00
Heating Ability
Firebox Area692 sq. ft
Grate Area108.20 sq. ft
Evaporative Heating Surface5666
Superheating Surface1724
Combined Heating Surface7390
Evaporative Heating Surface/Cylinder Volume201.22
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation28673
Same as above plus superheater percentage35362.07
Same as above but substitute firebox area for grate area226160.40
Power L127056.22
Power MT896.97

Credits

Introduction and specifications provided by Steve Llanso of Sweat House Media.