Western Pacific 4-8-4 "Northern" Locomotives in the USA

The Western Pacific Railroad took delivery of six 4-8-4s, Class GS-64 (road numbers 481 through 486) from the Lima Locomotive Works in 1943. These Northerns had 73.5 drivers, 27 x 30 cylinders, a 260 psi boiler pressure, weighed 466,100 pounds and had a tractive effort of 64,200 pounds.

Class Details by Steve Llanso of Sweat House Media

Class GS-64-77 (Locobase 6681)

Data from WP 3 - 1949 Steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 8017-8022 in June 1943.

Piggy-backing on the first of two Southern Pacific orders for its GS-6s was the Western Pacific, which took delivery of this sextet in 1943. [] (accessed 3 July 2006) shows that the unit price was $206,655.

According to Drury (1993), certain devices that held SP patents, like the oil burner, were removed, but the pointed smokebox and skyline casing,. After World War II, the WP added smoke deflectors.

The GS-64s went of service in the early 1950s, 485 operating last in October 1951 and both 483 and 486 closing out in January 1953. Three were then sold to the Southern Pacific for parts.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID6681
RailroadWestern Pacific (WP)
Number in Class6
Road Numbers481-486
Number Built6
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)20 / 6.10
Engine Wheelbase (ft / m)45.83 / 13.97
Ratio of driving wheelbase to overall engine wheebase 0.44
Overall Wheelbase (engine & tender) (ft / m)94.42 / 28.78
Axle Loading (Maximum Weight per Axle) (lbs / kg)70,237 / 31,859
Weight on Drivers (lbs / kg)280,950 / 127,437
Engine Weight (lbs / kg)465,100 / 210,966
Tender Loaded Weight (lbs / kg)397,700 / 180,394
Total Engine and Tender Weight (lbs / kg)862,800 / 391,360
Tender Water Capacity (gals / ML)23,300 / 88.26
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)6000 / 22.70
Minimum weight of rail (calculated) (lb/yd / kg/m)117 / 58.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)73.50 / 1867
Boiler Pressure (psi / kPa)260 / 17.90
High Pressure Cylinders (dia x stroke) (in / mm)27" x 30" / 686x762
Tractive Effort (lbs / kg)65,759 / 29827.82
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.27
Heating Ability
Firebox Area (sq ft / m2)451 / 41.91
Grate Area (sq ft / m2)90.20 / 8.38
Evaporative Heating Surface (sq ft / m2)4922 / 457.43
Superheating Surface (sq ft / m2)2086 / 193.87
Combined Heating Surface (sq ft / m2)7008 / 651.30
Evaporative Heating Surface/Cylinder Volume247.58
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation23,452
Same as above plus superheater percentage30,488
Same as above but substitute firebox area for grate area152,438
Power L141,576
Power MT1304.99

All material Copyright © SteamLocomotive.com
Wes Barris