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.
A 2-8-8-2, in the Whyte notation for describing steam locomotive wheel arrangements, is an articulated locomotive with a two-wheel leading truck, two sets of eight driving wheels, and a two-wheel trailing truck. The equivalent UIC classification is, refined to Mallet locomotives, (1'D)D1'. These locomotives usually employ the Mallet principles of articulation—with the rear engine rigidly attached to the boiler and the front engine free to rotate—and compounding. The 2-8-8-2 was a design largely limited to American locomotive builders. The last 2-8-8-2 was retired in 1962 from the N&W's roster, 2 years past the ending of steam though steam was still used on steel mill lines and other railroads until 1983.
The EMD DD35 was a 5,000 horsepower (3,700 kW) road switcher diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division for the Union Pacific Railroad and Southern Pacific Railroad.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 4-10-2 represents the arrangement of four leading wheels, ten powered and coupled driving wheels and two trailing wheels. In South Africa, where the wheel arrangement was first used, the type was known as a Reid Tenwheeler. In the United States of America it was known as a Southern Pacific on the Southern Pacific Railroad and as an Overland on the Union Pacific Railroad.
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 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 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 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-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 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 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 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 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 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 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. The MC-2 class was the first class of locomotives built and delivered to SP as cab forward locomotives in late 1909. 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.
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.
Spokane, Portland & Seattle 700 is the oldest and only surviving example of the class "E-1" 4-8-4 "Northern" type steam locomotive and the only surviving original Spokane, Portland and Seattle steam locomotive. It was built by the Baldwin Locomotive Works in May 1938. Nearly identical to the class "A-3" Northerns built for Northern Pacific Railway, it burns oil instead of coal.
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.
