Southern Pacific class AC-1

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Southern Pacific class AC-1
Southern Pacific reverse cab locomotive 4002.jpg
Southern Pacific No. 4002
Type and origin
Power typeSteam
Specifications
Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver dia.57 in (1,448 mm)
Adhesive weight 440,800 lb (199,900 kg)
Loco weight481,200 lb (218,300 kg)
Boiler pressure210 psi (1,400 kPa)
Feedwater heater 4​1⁄4-BL Worthington
Cylinder size 22 in × 30 in (559 mm × 762 mm) dia × stroke
Performance figures
Tractive effort 90,940 lbf (404.5 kN)
Career
Operators Southern Pacific Railroad
Class AC-1
Number in class15
Numbers4000 – 4010, 4012, 4014 – 4016
Retired1947 – 1948
DispositionAll scrapped

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. [1] The MC-2 class was the first class of locomotives built and delivered to SP as cab forward locomotives in late 1909. [1] The AC-1 class was the first of the successful AC series of cab forward locomotives that numbered nearly 200 in total on the SP. Southern Pacific No. 4002 was rebuilt in June 1923 as a Cab Forward.

Their rebuilds into class AC-1 was around June 1931. SP used the rebuilt locomotives through the traffic rush of World War II, then the SP 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 cab forward left in the United States of America is SP No. 4294, an AC-12 built in March 1944.

Related Research Articles

Southern Pacific Transportation Company United States Class I railroad (1865–1996)

The Southern Pacific was an American Class I railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was operated by various companies under the names Southern Pacific Railroad, Southern Pacific Company and Southern Pacific Transportation Company.

Cab forward

The term cab forward refers to various rail and road vehicle designs that place the driver's compartment substantially farther towards the front than is common practice.

Southern Pacific class GS-4

The GS-4 is a streamlined 4-8-4 "Northern" type steam locomotive used on the Southern Pacific Company from 1941 to 1958. They were built by the Lima Locomotive Works and were numbered 4430 through 4457. "GS" stands for "Golden State" or "General Service."

Southern Pacific class AC-4

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 (Mallet-Consolidation) class 2-8-8-2 locomotives with a larger firebox, hence, the four-wheel leading truck.

Southern Pacific class AC-5

Southern Pacific Railroad'sAC-5 class of steam locomotives was the railroad's second class of 4-8-8-2 cab forward locomotives. They were built between July and September 1929 and placed in service soon after construction. The AC-5 class was only slightly larger than the AC-4 class.

Southern Pacific class AC-6

Southern Pacific Railroad's AC-6 class of steam locomotives was the third of the railroad's classes built with a 4-8-8-2 wheel arrangement. Like the earlier AC-4 and AC-5 classes, the AC-6 class were cab forward locomotives. The AC-6 was slightly larger than the previous classes with a higher boiler pressure and tractive effort rating.

Southern Pacific Railroad's AC-7 class of cab forward steam locomotives was the fourth class of the 4-8-8-2 locomotives purchased by Southern Pacific (SP). The locomotives were built by Baldwin Locomotive Works and shared many of the same characteristics of previous AC class locomotives.

Southern Pacific class AC-8

Southern Pacific Railroad's AC-8 class of cab forward steam locomotives was the fifth of SP's 4-8-8-2 classes. They were built by Baldwin Locomotive Works in 1939.

Southern Pacific Railroad's AC-10 class was the largest class of cab forward steam locomotives produced for the railroad. The design of this and the previous AC classes proved so successful for SP that the railroad began placing orders for the AC-10's successors, AC-11s, while Baldwin Locomotive Works was still busy building and delivering the AC-10s. Mechanically, the AC-10s were exceptionally similar to their immediate predecessors, the AC-8s.

Southern Pacific class AC-11

Southern Pacific Railroad's AC-11 class of cab forward steam locomotives was the seventh class of 4-8-8-2 locomotives ordered by Southern Pacific (SP) from Baldwin Locomotive Works; SP was so pleased with the AC-10 class built a year earlier that the railroad began placing orders for AC-11s while the AC-10s were still being built and delivered. They were built between November 1942 and April 1943, closely resembling the AC-10s.

Southern Pacific class AC-12

Southern Pacific Railroad's AC-12 class of cab forward steam locomotives was the last class of steam locomotives ordered by Southern Pacific. They were built by Baldwin Locomotive Works during World War II, with the first, number 4275, entering service on October 27, 1943, and the last, 4294, on March 19, 1944. The locomotives were effectively a conventional 2-8-8-4 locomotive running in reverse; the tender being coupled at the smokebox end of the locomotive. This was made possible by the use of oil-firing. The distinct features of these locomotives include: a streamlined front with white band, an air horn on the front, a streamlined pilot, a SP 12 wheel box tender, and air compressors mounted on the smokebox. Southern Pacific used these locomotives all over its system, but they were extremely famous for working on Donner Pass & Cascade Summit.

Southern Pacific 4294 Preserved SP cab-forward locomotive (SP AC-12 class)

Southern Pacific 4294 is a class "AC-12" 4-8-8-2 Cab forward type steam locomotive that was owned and operated by the Southern Pacific Railroad (SP). It was built by the Baldwin Locomotive Works in March 1944 and was used hauling SP’s trains over the Sierra Nevada, often working on Donner Pass in California. Today it is preserved at the California State Railroad Museum (CSRM) in Sacramento, California.

Southern Pacific class MM-2

Southern Pacific Company's MM-2 class of steam locomotives was Southern Pacific's (SP) only class of 2-6-6-2 locomotives ordered and built as oil-fired cab forward locomotives. They were built in 1911 as compound-expansion Mallet locomotives by Baldwin Locomotive Works and entered service on SP beginning September 19, 1911. By 1914, they had all been upgraded with an additional leading axle making them 4-6-6-2 locomotives, reclassified from MM-2 to AM-2. This was done to improve handling at speed. These locomotives were the predecessors of several other cab-forward engines, culminating in the AC-12 class cab forward locomotives built during World War II.

Southern Pacific class MC-1

Southern Pacific Railroad's MC-1 class of steam locomotive consisted of two locomotives built by Baldwin Locomotive Works in April 1909. They are the first two locomotives converted by Southern Pacific (SP) to run as cab forward locomotives.

Southern Pacific class MC-2

Southern Pacific Railroad's MC-2 class of steam locomotives was the first class to be ordered by and built for Southern Pacific (SP) as cab forward locomotives. They were built in 1909 following the design of SP's MC-1 class built earlier that year. The success of this locomotive model led to the design and introduction of the AC class of 4-8-8-2 cab forward locomotives in the 1930s and 1940s.

Southern Pacific class MC-4

Southern Pacific Railroad's MC-4 class of steam locomotive was the second class ordered and built as cab forward locomotives. Southern Pacific (SP) found the MC-2 class sufficient for a proof-of-concept for cab forward locomotives and sought to continue with now tested designs.

Southern Pacific Railroad's AC-2 class of steam locomotives was the second in the AC series of cab forward locomotives built for Southern Pacific (SP). This class consisted of locomotives that were rebuilt from Baldwin-built SP MC-4 class locomotives by 1930.

Southern Pacific Company's MC-6 class of steam locomotives is made up of two batches: the first consisting of 15 locomotives weighing 435,800 pounds built in 1912, the second consisting of 5 locomotives weighing 437,100 lb built in 1913. All of the locomotives were built by Baldwin Locomotive Works. This was the last class of 2-8-8-2 locomotives that Southern Pacific (SP) ordered as cab forward locomotives.

Southern Pacific Railroad's AC-3 class of steam locomotive was the 3rd and last cab forward design based on the 2-8-8-2 wheel arrangement. All 20 locomotives in this class were rebuilds from MC-6 class locomotives originally built by Baldwin Locomotive Works in 1912 and 1913. The rebuilds all took place in the late 1920s at Southern Pacific's Sacramento shops.

Southern Pacific Company's AM-2 class of steam locomotives was Southern Pacific's (SP) only class of 4-6-6-2 locomotives ordered and built as cab forward locomotives. They were actually MM-2s that had been upgraded. MM-2s were built in 1911 by Baldwin Locomotive Works and entered service on SP beginning September 19, 1911. By 1914, they had all been upgraded with an additional leading axle making them 4-6-6-2 locomotives. They reclassified their MM-2 as AM-2. This was done to improve handling at speed. These locomotives were the predecessors of the AC-12 class cab forward locomotives built during World War II.

References

Specific
  1. 1 2 Yenne (1996) , p. 96.


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