Southern Pacific class AC-4

Infobox Locomotive
name=Southern Pacific class AC-4
powertype=Steam
gauge=4 ft 8½ in (1435 mm)
railroad=Southern Pacific Railroad
whytetype=4-8-8-2
railroadclass=AC-4
driversize=63 in diameter
cylindersize=24 in dia × 32 in stroke
weight=614,600 lb (278,800 kg)
weightondrivers=475,200 lb (215,500 kg)
boilerpressure=235 psi (1.62 MPa)
tractiveeffort=112,760 lbf (501.6 kN), 116,900 lbf (520.0 kN) rebuilt
builder=Baldwin Locomotive Works
builddate=August-October 1928
serialnumber=60575, 60576, 60623-60625, 60666-60669
numinclass=10
roadnumber=4100 – 4109
feedwaterheater=4¼-BL Worthington
firstrundate=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 convert|112760|lbf|abbr=on of tractive effort; after a January 1931 rebuild, this class was capable of convert|116900|lbf|abbr=on of tractive effort.

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

References

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