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The ALCO 251 is a 4-stroke diesel engine that was developed by the American Locomotive Company to replace its 244 and 539 engines. The 251 was developed to be used in diesel locomotives, as a marine power plant in ships, and as a stationary power generator.
The model 251 engine design was initiated in 1949 and, like the 244 engine, it had a bore (cylinder diameter) of 9 inches (229 mm), and a stroke of 10.5 inches (267 mm). Its designation combines Alco's identifier for that bore and stroke - 2 - with the year its design was approved for laboratory testing - 1951. Chief Engineer of Diesel Engine Design, Paul Vaughan, designed the 251 to improve upon the major weaknesses of the 244. A wet block design was used to overcome severe thermal differences which existed in the dry block 244. The welded block and base was kept, as was the four-point mounting. New in the 251 was an intercooler for the turbocharger, which minimized temperature differentials and also benefited performance. Many small improvements were made to the crankshaft, bearings, pistons, injectors and camshafts.
To avoid the problems caused by rushing the 244 into production, the 251 was put through an extensive testing process. The first 251 engines installed in locomotives for testing were inline-6 designs of 800 hp (597 kW). [1] A simple, safe design, it also offered a direct replacement for the aged 539, which was still used in switch engines and the ALCO RS-1 road switcher. Like the 539, it was produced in Auburn, New York. [1] In August 1951, Alco built the ALCO DL420 test unit with a six-cylinder 800-horsepower 251 engine. [2] Ten GE 78-ton units followed in mid-1953 and were exported to the Consolidated Railroads of Cuba. [3] The following year seven ALCO S-5, a demonstrator and six units for the Boston and Maine were built. [4] Two GE X3341s were built in 1954 for the White Pass and Yukon Route with the 251 engines. [2] In mid-1954 the Lehigh Valley Railroad supplied an FA-2 and FB-2 for installation of test 12-cylinder 251A engines. The Lehigh Valley units were tested for a year.
In 1954, the 251 went into production with the inline-6 at Auburn, New York. The next year production of the V-12 followed at Auburn, New York - where the 539 engine was built - and a V-16 version built at Schenectady, New York, replacing the 244. Engine manufacturing at Schenectady was terminated in 1962, after which all non-Canadian production was moved to Auburn. [1] Engines for A. E. Goodwin, Alco's Australian licensee, were built at Auburn or Schenectady; [1] engines for Montreal Locomotive Works were, until 1961, assembled by MLW using parts supplied by Auburn and Schenectady. After that date, they were built under licence in Canada by the Dominion Engineering Works. [1]
The inline-6 designs of 800 hp (597 kW) version of the 251 engine replaced the 539 engine in 1954 in Alco's low-end line of power generation packages. The 244 engine was still used in higher-end power generation packages until it too was replaced by 251-engined power generation equipment in 1956.
A pair of Alco 251C engines is also used for powering the 6,000,000 lb (2,721,554 kg) NASA Crawler Transporter that transport rockets and their platforms from the Vehicle Assembly Building to the Launch Complex 39.
Ultimately a refined and successful design, the 251 outlived Alco. For a time it was built in Canada by Montreal Locomotive Works. As of November 2023, Fairbanks Morse still lists the 251 on its website for power generation. [5]
| Engine type | Power (hp) | Locomotive(s) |
|---|---|---|
| inline-6 251A | 800 | S-5, [2] GE 78 Ton, [6] GE X3341. [2] |
| inline-6 251B | 900 | S-6. [4] , SB-8/SSB-9. [7] |
| inline-6 251B | 1,000 | T-6. [7] DL531. DL532 |
| inline-6 251C | 1,000 | S-13, [8] RS-23. |
| inline-6 251D | 1,200 | DL535E. |
| V-8 251D | 1,500 | C-415. [9] |
| V-12 251B | 1,800 | RS-11, [10] RSD-12, [11] RS-18, [12] RS-36, [13] FPA-4, [14] FPB-4. [14] |
| V-12 251C | 2,000 | RS-32, [15] C420, [16] DH643, M-420. |
| V-12 251E | 2,400 | M424, HR-412. |
| V-16 251B | 2,400 | RS-27, [17] RSD-15, [18] RSD-17, [19] C-424. [20] |
| V-16 251C | 2,500 | C-425. [21] |
| V-16 251C | 2,750 | C-628, [22] C-855, [23] C-855B. [23] |
| V-16 251E | 3,000 | C-430, [23] C-630, [24] M-630. |
| V-16 251E | 3,200 | HR-616. [25] |
| V-16 251F | 3,600 | C636, [26] M-636. |
| V-16 251F | 3,700 | LRC-2, LRC-3. |
| V-18 251F | 4,000 | M-640. [26] |
A V16 engine is a sixteen-cylinder piston engine where two banks of eight cylinders are arranged in a V configuration around a common crankshaft. V16 engines are less common than engines with fewer cylinders, such as V8 and V12 engines. Each bank of a V16 engine can be thought of as a straight-8, a design that can be inherently balanced. Most V16 engines have a 45° bank angle.
The American Locomotive Company was an American manufacturer of locomotives, diesel generators, steel, and tanks that operated from 1901 to 1969.
The ALCO Century Series locomotives were a line of road switcher locomotives produced by Alco, the Montreal Locomotive Works and AE Goodwin under license in Australia.
The ALCo Century 636 was the most powerful single-engine diesel-electric locomotive constructed by the American Locomotive Company (ALCo). It used their 251 prime mover. The locomotive had a C-C wheel arrangement and 3,600 horsepower (2,700 kW). The locomotive rode on a pair of trucks of all-new design, known as the Hi-Ad, standing for 'high adhesion'. Visually, it is similar to the Century 630, but can be distinguished by the intercooler box. The C630 has two grilles here, one above the other. The C636 only has the upper grille.
The ALCO C-643DH, also known as the Century 643DH, was a twin-engine diesel-hydraulic locomotive, the first diesel-hydraulic road switcher built in the United States. It had a C-C wheel arrangement and generated 4,300 horsepower (3,200 kW). Only three were built, all for Southern Pacific Railroad in 1964 (#9018–#9020). The Alco C-643DHs joined 21 Krauss-Maffei ML-4000 diesel-hydraulics already on the Southern Pacific's roster. They spent most of their service lives in the flat San Joaquin Valley in California.
The ALCO HH series was an early set of diesel switcher locomotives built by the American Locomotive Company (ALCO) of Schenectady, New York between 1931 and 1940, when they were replaced by the S series: the 660 hp (490 kW) S-1 and 1,000 hp (750 kW) S-2. They were ALCO's first diesel switchers to enter true series production, and among the first land vehicles anywhere to use the revolutionary diesel-electric power transmission.
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Electro-Motive Diesel is a brand of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. Formerly a division of General Motors, EMD is now owned by Progress Rail, a subsidiary of Caterpillar Inc. Electro-Motive Diesel traces its roots to the Electro-Motive Engineering Corporation, founded in 1922 and purchased by General Motors in 1930. After purchase by GM, the company was known as GM's Electro-Motive Division. In 2005, GM sold EMD to Greenbriar Equity Group and Berkshire Partners, and in 2010, EMD was sold to Progress Rail. Upon the 2005 sale, the company was renamed to Electro-Motive Diesel.
The ALCO RSD-15 is a diesel-electric locomotive built by the American Locomotive Company (ALCO) of Schenectady, New York between August 1956 and June 1960, during which time 75 locomotives were produced. The RSD-15 was powered by an ALCO 251 16-cylinder four-cycle V-type prime mover rated at 2,400 horsepower (1.79 MW); it superseded the almost identical ALCO 244-engined RSD-7, and was catalogued alongside the similar but smaller 1,800 hp (1.34 MW) RSD-12, powered by a 12-cylinder 251-model V-type diesel engine.
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The ALCO RSD-7 was a diesel-electric locomotive of the road switcher type built by ALCO at Schenectady, New York between January 1954 and April 1956. Two versions were built, with the same RSD-7 model designation but different specifications and power ratings, although both used the ALCO 244 engine in V16 configuration. Specification DL-600, of which only two were built, developed 2,250 hp and used the 244G engine. The revised specification DL-600A, numbering 27 locomotives, was rated at 2,400 hp and used the 244H engine. The RSD-7 was superseded by the ALCO 251-engined ALCO RSD-15, which looks very similar. The RSD-7 was the last ALCO diesel built with a 244 engine.
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The ALCO DL-202-2 and DL-203-2 diesel-electric locomotive was an experimental freight locomotive produced by ALCO of Schenectady, New York. The primary diesel builders Alco, Baldwin and EMD pushed the War Production Board (WPB) for more opportunities to build more diesels. The Transportation Equipment Division of the WPB announced a production schedule on December 10, 1943, that allowed Alco to build one 4500 horsepower experimental diesel locomotive. This experimental diesel locomotive was to be built in the fourth quarter of 1944. The two A units were built in January 1945 and the B unit at a later date in 1945. The two A units were put on test at Building No. 37 at Schenectady to work out problems with the connecting rods and turbocharger in the Alco 241 engine, developed by both McIntosh and Seymour and ALCo. The total production run included 2 cab DL202-2 A units, and a single DL203-2 B unit. The locomotives were powered by a V12 ALCO 241 diesel engine, rated at 1,500 hp (1.1 MW). The units were released for test in September 1945. The locomotive could attain a top speed of 80 mph (130 km/h) (Freight) and 125 mph (201 km/h) (Passenger). With the B-B wheel arrangement and carbody construction, equipment layout and electrical gear these experimental units were the immediate predecessors of the FA units to come in early 1946. Outwardly, the bodies strongly resembled those on the DL-109, some of which were still under construction at Schenectady in early 1945.
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The ALCO 241 was a diesel prime mover built by the American Locomotive Company (ALCO). It was the company's first diesel engine originally designed to power road locomotives, with a higher output and operating speed than previous designs.
The ALCO 244 was a diesel prime mover built by the American Locomotive Company (ALCO). An evolution of the earlier 241 diesel engine, it powered ALCO's first generation of production road locomotives. The 244 engine was developed to create an engine capable of being used in railroad freight and passenger locomotives. The 244 engine was also used in a very limited basis as a marine power plant in ships and as a stationary power generator.