Proto 2000 Ho Scale Alco PA/PB Locomotive Set - Union Pacific

ALCO PA refers to a family of A1A-A1A diesel locomotives built to haul passenger trains built in Schenectady, New York in the United States by a partnership of the American Locomotive Company (ALCO) and General Electric (GE) between June, 1946 and December, 1953. They were of a cab unit design, and both cab-equipped lead A unit PA and cabless booster B unit PB models were built.

The PAs, as well as their cousins, the ALCO FAs, were born as a result of Alco's development of a new diesel engine design, the Model 244. In early 1944, development started on the new design, and by early 1946, the first engines were beginning to undergo tests. This unusually short testing sequence was brought about by the decision of Alco's senior management that the engine and an associated line of road locomotives had to be introduced no later than the end of 1946. In preparation for this deadline, by January of 1946, the first 244 engines were being tested, and while a strike delayed work on the locomotives, the first two PA units were released for road tests in June 1946, for testing for one month on the Lehigh Valley Railroad. After these first tests were completed, the locomotives returned to the factory for refurbishment and engine replacement. In September 1946, the first production units, an A-B-A set of PA1s in Santa Fe colors were released from the factory, and sent to New York's Waldorf-Astoria Hotel, which had a private railroad siding, for exhibition before being launched into road service.

Two different models were offered: the 2,000 horsepower (1,500 kW) PA-1/PB-1 (built between September, 1946 and June, 1950); the 2,250 horsepower (1,680 kW) PA-2/PB-2 (built between April, 1950 and December, 1953)

Models popularly termed the PA-3/PB-3 were in fact only an upgrade of the PA-2/PB-2. The true PA-3/PB-3 model would have boasted 2,400 horsepower (1,800 kW), though none were ever built. Aside from the small power increase between the PA-1 and the PA-2, differences between the models were minor. Externally, PA-3s could be distinguished by the absence of the "eyebrow" trim piece on the grille behind the cab and the porthole window behind the radiator shutters. Internally, later PA-2 and PB-2 production featured a water-cooled turbocharger and other engine compartment changes, but these were frequently added to older models undergoing major repairs and/or overhauls.

Like its smaller cousin, the ALCO FA, the PA had distinctive styling, with a long, straight nose tipped by a headlight in a square, slitted grille, raked windshields, and trim pieces behind the cab windows that lengthened and sleekened the lines. The overall design owed something to the Fairbanks-Morse Erie-built design, which had been constructed by ALCO's electrical equipment partner General Electric at their Erie, Pennsylvania plant. The majority of PA components were compatible with the FA.

Fans deemed the PA one of the most beautiful diesels by design and an "Honorary Steam Locomotive", with the first being Professor George W. Hilton in a book review in the September, 1968, Trains Magazine,[2] because of a peculiarity of the ALCO 244 diesel prime mover when accelerating. Until the turbocharger came up to speed, thick clouds of black smoke would pour from the exhaust stacks, due to turbo lag. Photographing a moving PA while smoking became a prime objective of railfans.[3]

The ALCO 244 V16 diesel prime mover proved to be the undoing of the PA: The engine had been rushed into production, and proved to be unreliable in service. The PA locomotives failed to capture a marketplace dominated by General Motors Electro-Motive Division and their E-units. The original Santa Fe three unit set #51L, 51A and 51B was repowered in August 1954 with EMD 16-567C engines rated at 1,750 hp (1,305 kW). This EMD repowering of the PAs was economically unfeasible and the remaining Santa Fe PAs retained their 244 engines. The later 251-series engine, a vastly improved prime mover, was not available in time for ALCO to recover the loss of reputation caused by the unreliability of the 244. By the time the ALCO 251 engine was accepted into widespread use, General Electric (which ended the partnership with ALCO in 1953) had fielded their entries into the diesel-electric locomotive market. General Electric eventually supplanted ALCO as a manufacturer of locomotives. ALCO's loss of market share led to its demise in 1969.

See Union Pacific Model Trains: Athearn HO Scale C44-9W Locomotive - Union Pacific / Bachmann HO Scale Pacific Flyer Electric Train Set - Union Pacific / Athearn HO Scale GE AC4400 Locomotive - Union Pacific / Trainline HO Scale Alco FA-1 Locomotive - Union Pacific / Athearn HO Scale 4-8-4 Nothern "800" Locomotive - Union Pacific / Athearn HO Scale 50ft Combo Door Box Car - Union Pacific

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