Southern Pacific class AC-4

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Southern Pacific class AC-4
Power type Steam
Builder Baldwin Locomotive Works
Serial number 60575, 60576, 60623-60625, 60666-60669
Build date August-October 1928
Configuration 4-8-8-2
Gauge ft 8½ in (1435 mm)
Driver size 63 in diameter
Weight on drivers 475,200 lb (215,500 kg)
Locomotive weight 614,600 lb (278,800 kg)
Boiler pressure 235 psi (1.62 MPa)
Feedwater heater 4¼-BL Worthington
Cylinder size 24 in dia × 32 in stroke
Tractive effort 112,760 lbf (501.6 kN), 116,900 lbf (520.0 kN) rebuilt
Career Southern Pacific Railroad
Class AC-4
Number in class 10
Number 4100 – 4109
First run October 1928
Disposition scrapped

Southern Pacific Railroad's AC-4 class of steam locomotives was the first class of cab forward locomotives built with the 4-8-8-2 wheel arrangement. They were designed as an improvement upon the railroad's existing MC class 2-8-8-2 locomotives having a larger firebox.

The AC-4s were built in August through October 1928 by Baldwin Locomotive Works. As delivered, they produced 112,760 lbf (501,600 N) of tractive effort; after a January 1931 rebuild, this class was capable of 116,900 lbf (520,000 N) of tractive effort.

All ten of the AC-4s were removed from active service between 1953 and 1955 and scrapped by June 1955.

[edit] References

  • Diebert, Timothy S. and Strapac, Joseph A. (1987). Southern Pacific Company Steam Locomotive Conpendium. Shade Tree Books. ISBN 0-930742-12-5.