Classic Streamliners - TRAINCYCLOPEDIA
Southern Pacific AC-4 No. 4100 and crew.
Southern Pacific Class AC-4 Articulated Consolidation Cab Forward Steam Locomotive
Southern Pacific Railroad's AC-4 class of steam locomotives were the first class of 4-8-8-2 cab forward locomotives. They were intended to improve on the railroad's MC class 2-8-8-2 locomotives with a larger firebox.
The AC-4s were the first SP Mallets built for simple expansion. Baldwin Locomotive Works built them in August through October of 1928 with a maximum cutoff of 70%, so tractive effort was rated at 112,760 lbf (501.6 kN); a few years later limited cutoff was dropped and calculated tractive effort increased to 116,000 lbf (520 kN).
The AC-4s were removed from service starting in 1953 and all ten were scrapped by June 1955.
Southern Pacific class AC-4 Overview
Type and origin
Power type: Steam
Builder: Baldwin Locomotive Works
Serial numbers: 60575, 60576, 60623-60625, 60666-60669
Build dates: August–October 1928
Gauge: 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver diameter: 63 in (1,600 mm)
Adhesive weight: 475,200 lb (215,500 kg; 215.5 t)
Loco weight: 614,600 lb (278,800 kg; 278.8 t)
Boiler pressure: 235 psi (1.62 MPa)
Feedwater heater: 4¼-BL Worthington
Cylinder size 24 in × 32 in (610 mm × 813 mm) (bore × stroke)
Tractive effort: 112,760 lbf (501.6 kN), 116,900 lbf (520 kN) rebuilt
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Text: wikipedia.org. Images: Public Domain; http://www.commons.wikimedia.org (unless otherwise specified) and 17 U.S. Code § 107 fair use. References: Lewis, Robert G. The Handbook of American Railroads. New York: Simmons-Boardman Publishing Corporation, 1951, 2nd Edition 1956. Site Map Contact webmaster HERE.