The reference for locomotives and railcars
Southern Pacific classes GS-3 to GS-5
United States | 1937 | 44 produced
GS-4 No. 4444
GS-4 No. 4444
collection Taylor Rush

After the GS-1 and GS-2, Southern Pacific decided to design additional express locomotives in the “Golden State” series for higher speeds. By increasing the size of the drivers from 73.5 to 80 inches, the GS-3 was created, which also pulled the “Coast Daylight”. Since there were many gradients on the line between Los Angeles and San Francisco, the tractive force was compensated for by a longer cylinder stroke and higher boiler pressure.

Like the GS-2, the GS-3 stood out with its partial streamlined fairing and striking color scheme of orange, red, silver and black. After 14 GS-3s built in 1937, a total of 28 GS-4s were built in 1941 and 1942. These differed from the GS-3 mainly in a booster in the trailing bogie. They also had a faster-acting, electro-pneumatic brake, which was later removed.

During World War II, the Southern Pacific wanted to build more locomotives of this type, but the government only allowed the construction of freight locomotives. Thus, the abbreviation GS was reinterpreted from “Golden State” to “General Service”, which would indicate that these locomotives were suitable for freight and passenger trains.

In 1942 only two GS-5s were built, which now had roller bearings on all axles. The later developed GS-6 again had smaller wheels and was actually suitable for mixed service. The GS-3 to GS-5 were retired in 1957 and 1958 and largely scrapped. Among the only two members of the GS series that still exist today is the GS-4 No. 4449, which is operational.

Axle config4-8-4 (Northern) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase47 ft 8 in
Fixed wheelbase21 ft 6 in
Total wheelbase96 ft 3 in
Service weight460,000 lbs475,000 lbs483,200 lbs
Adhesive weight267,300 lbs275,700 lbs278,700 lbs
Total weight818,880 lbs788,730 lbs881,800 lbs
Axle load67,000 lbs69,000 lbs70,000 lbs
Water capacity22,000 us gal23,300 us gal
Fuel capacity60,100 us gal (oil)6,275 us gal (oil)5,978 us gal (oil)
Power sourcesteam
Estimated power5,000 hp (3,729 kW)5,200 hp (3,878 kW)
Optimal speed50 mph48 mph50 mph
Starting effort64,355 lbf66,326 lbf
Booster13,000 lbf13,200 lbf
Power Plant
Driver diameter80 in
Boiler pressure280 psi300 psi
Expansion typesimple
Cylinderstwo, 26 x 32 intwo, 25 1/2 x 32 in
Grate area90.4 sq ft
Firebox area388 sq ft385 sq ft388 sq ft
Tube heating area4,502 sq ft
Evaporative heating area4,890 sq ft4,887 sq ft4,890 sq ft
Superheater area2,565 sq ft1,834 sq ft2,086 sq ft
Total heating area7,455 sq ft6,721 sq ft6,976 sq ft
Calculated Values
steam locomotive
last changed: 12/2023

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