Power type Steam | Build date August–October 1928 | |
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Serial number 60575, 60576, 60623-60625, 60666-60669 Gauge 4 ft 8 ⁄2 in (1,435 mm) standard gauge | ||
Southern Pacific Railroad's AC-4 class of steam locomotives was 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 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.
References
Southern Pacific class AC-4 Wikipedia(Text) CC BY-SA