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Southern Pacific class A-6
United States | 1927 | 4 produced
No. 3002 in September 1941 in Los Angeles
No. 3002 in September 1941 in Los Angeles
Theodore A. Gay

All A-3 Atlantics built from 1904 onwards were fitted with a superheater from 1920 and most of them also received a feedwater heater and a booster on the trailing axle. Four underwent an even bigger rebuild in the Southern Pacific workshops, resulting in the class A-6. Two each were completed in August 1927 and October 1928.

As opposed to other rebuilds with a driver diameter of 77 inches, the A-6 retained the original 81 inches. In addition, the diameter of the cylinders was increased by two inches and the boiler pressure was increased by ten psi. The tube heating surface has been increased by about five percent and the frame has been strengthened. In total, this resulted in a service mass increased by around 20 tons. Their duties included the haulage of the Sacramento Daylight.

ManufacturerSouthern Pacific
Axle config4-4-2 (Atlantic) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase28 ft 8 in
Fixed wheelbase7 ft
Total wheelbase78 ft 8 1/2 in
Service weight243,899 lbs
Adhesive weight126,700 lbs
Total weight417,899 lbs
Axle load64,501 lbs
Fuel capacitycoal
Power sourcesteam
Estimated power1,700 hp (1,268 kW)
Optimal speed36 mph
Starting effort29,865 lbf
Booster11,520 lbf
Power Plant
Driver diameter81 in
Boiler pressure210 psi
Expansion typesimple
Cylinderstwo, 22 x 28 in
Grate area49.5 sq ft
Firebox area176 sq ft
Tube heating area2,129 sq ft
Evaporative heating area2,305 sq ft
Superheater area435 sq ft
Total heating area2,740 sq ft
Calculated Values
steam locomotive
last changed: 07/2022

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