Classic Streamliners - TRAIN​CYCLOPEDIA

Southern Pacific Class AC-1 2-8-8-2 Cab Forward Steam Locomotive
Southern Pacific Railroad's AC-1 class of cab forward steam locomotives consisted of locomotives rebuilt from MC-1 and MC-2 class locomotives that were originally built by Baldwin Locomotive Works in 1909. The MC-2 class was the first class of locomotives built and delivered to SP as cab forward locomotives. The Southern Pacific's AC-1 class was the first of the successful AC series of cab forward locomotives, numbering nearly 200 in total. Southern Pacific No. 4002 was rebuilt as a cab forward in June of 1923.

The class AC-1 rebuilds took place around June of 1931. SP used the rebuilt locomotives through the traffic rush of World War II, and removed them from the roster soon after the war. They were all retired from active service by 1949 and were scrapped soon after their retirement. The last locomotive of this class that was scrapped was number 4014 on April 12, 1949. None of the original AC-1's were preserved. The only remaining cab forward in the United States is SP No. 4294, a AC-12 built in March 1944, 4-5 Years before most AC-1's were retired.

Southern Pacific Class AC-1 Overview
Type and origin
Power: type Steam

Whyte Wheel Arrangement: 2-8-8-2
Gauge: 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver diameter: 57 in (1,448 mm)
Adhesive weight: 440,800 lb (199,900 kg)
Locomotive weight: 481,200 lb (218,300 kg)
Boiler pressure: 210 psi (1,400 kPa)
Feedwater heater: 4¼-BL Worthington
Cylinder size: 22 in × 30 in (559 mm × 762 mm) dia × stroke
Performance figures
Tractive effort: 90,940 lbf (404.5 kN)
Operator: Southern Pacific Railroad
Class: AC-1
Number in class: 15
Numbers: 4000 – 4010, 4012, 4014 – 4016
Retired: 1947 – 1948
Disposition: scrapped

See also:

Cab Forward Locomotives

Steam Locomotives

SP MC-1 Locomotive

2-8-8-2 Locomotives

Southern Pacific


Baldwin logo.
SP herald.

Southern Pacific Class AC-1 Cab Forward No. 4002.

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