Western Pacific 4-8-4 "Northern" Locomotives of 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 Raildata collection. 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. http://www.wplives.com/motivepower/srosters/Class_481_Roster__/class_481-407_roster__.html (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.

Specifications 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 Wheelbase20'
Engine Wheelbase45.83'
Ratio of driving wheelbase to overall engine wheebase 0.44
Overall Wheelbase (engine & tender)94.42'
Axle Loading (Maximum Weight per Axle)70237 lbs
Weight on Drivers280950 lbs
Engine Weight465100 lbs
Tender Light Weight397700 lbs
Total Engine and Tender Weight862800 lbs
Tender Water Capacity23300 gals
Tender Fuel Capacity (oil/coal)6000 gals
Minimum weight of rail (calculated)117 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73.50"
Boiler Pressure260 psi
Cylinders (dia x stroke)27" x 30"
Tractive Effort65759 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.27
Heating Ability
Firebox Area451 sq. ft
Grate Area90.20 sq. ft
Evaporative Heating Surface4922 sq. ft
Superheating Surface2086 sq. ft
Combined Heating Surface7008 sq. ft
Evaporative Heating Surface/Cylinder Volume247.58
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation23452
Same as above plus superheater percentage30488
Same as above but substitute firebox area for grate area152438
Power L141576
Power MT1304.99



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