GS-6

Southern Pacific GS-6 Western Pacific GS-64-77
SP 4460, the oldest (and sole-remaining) GS-6 at the Museum of Transportation
Type and origin Power type Steam Builder Lima Locomotive Works Serial number SP: 8013–8016, 8248–8253 WP: 8017–8022 Build date July–August 1943 Total produced 16
Specifications Configuration: ​  • Whyte 4-8-4  • UIC 2′D2′ h2 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Driver dia. 73 1⁄2 in (1,867 mm) Axle load 67,900 lb (30,800 kilograms; 30.8 metric tons) Adhesive weight 283,200 lb (128,500 kg; 128.5 t) Loco weight 468,400 lb (212,500 kg; 212.5 t) Total weight 786,200 lb (356,600 kg; 356.6 t) Firebox:  • Firegrate area 90 sq ft (8.4 m2) Boiler pressure 260 psi (1.79 MPa) Heating surface 4,582 sq ft (425.7 m2) Superheater: ​  • Heating area 2,086 sq ft (193.8 m2) Cylinder size 27 in × 30 in (686 mm × 762 mm) Valve gear Walschaerts
Performance figures Tractive effort 64,600 lbf (287.36 kN), 76,050 lbf (338.29 kN) with booster
Career Operators Southern Pacific and Western Pacific Class SP: GS-6 WP: GS-64-77 Number in class SP:10 WP: 6 Numbers SP 4460–4469, WP 481–486 Nicknames "War Babies", "Baby Daylights" First run 1943 Retired 1953 (WP), 1958 (SP) Disposition SP 4460 preserved, remainder scrapped

The GS-6 is a semi-streamlined 4-8-4 Northern type steam locomotive that served the Southern Pacific Railroad from 1943 to 1958 and the Western Pacific Railroad from 1943 to 1953. A total of ten were built during World War II for the Southern Pacific Railroad by the Lima Locomotive Works and were numbered 4460 through 4469 for Southern Pacific and 481 through 486 for Western Pacific. GS stands for "Golden State" or "General Service."

In 1943 when the Southern Pacific Railroad placed an order for fourteen new "Daylight" locomotives from Lima, World War II was raging, and the War Production Board dictated what types of locomotives could be manufactured. SP's order was turned down, with the government declaring that streamlined passenger engines were not necessary and would not help in moving wartime traffic. Southern Pacific re-designed the engines for general service and it was finally approved. The smaller and power-starved Western Pacific Railroad was also looking for locomotives at the time and had first requested diesels, then a different style of steam locomotive. The War Production Board instead diverted six GS-6s (reportedly to have been numbered SP 4470-4475) to the WP. SP patented items were not included and the WP requested Franklin boosters be installed, making them slightly different from the SP engines upon delivery. The WP referred to them as GS-64-77s.

The GS-6 looked similar to the GS-2 with a silver smokebox with a cone-shaped single headlight casing and 73-inch (1.854 m) drivers. Like all GS engines they had teardrop classification lights and an air horn to supplement their whistle. They retained the skyline casing on the top of the boiler but did not have the side skirting of previous GS locomotives. Southern Pacific's GS-6s also lacked the orange and red "Daylight" paint scheme that the previous GS engines so famously wore. Western Pacific's GS-6s received "elephant ears" similar to that of the Union Pacific Railroad's 4-8-4 locomotives.