This article needs additional citations for verification. (August 2016)
The EMD SW1 is a 600-horsepower (450 kW) diesel-electric switcher locomotive built by General Motors' Electro-Motive Corporation (later Division) between December 1938 and November 1953. Final assembly was at EMD's plant at LaGrange (McCook) Illinois. The SW1 was the second generation of 3,402 cu in (55.75 L) switcher from EMD, succeeding the SC (cast frame) and SW (welded frame). The most significant change from those earlier models was the use of an engine of EMD's own design, the then-new 567 engine, here in 600 hp (450 kW) V6 form. 661 locomotives of this design were built, with a gap in production between March 1943 and September 1945 due to World War II.
The SW1 was the start of a long line of SW series switchers produced by EMD. It was complemented by the SW7 in 1949 and the SW8 in 1950. SW1 production ceased in November 1953, with its replacement, the equally powerful SW600, starting production in February 1954.
EMD arrived at the name SW1 based on the locomotive's power (S for 600 hp) and frame design (W for welded), and the number 1 was added to distinguish the new design from the previous EMD SW. As new and more powerful SW designs emerged in the 1950s, the SW name evolved to instead stand for "switcher."
Engine and powertrain
The SW1 introduced a 6-cylinder version of the 567 (later 567A) series engine to EMC/EMD switchers. Developing 600-horsepower (450 kW) at 800 rpm, this engine remained in production until 1966. Designed specifically for railroad locomotives, this was a supercharged 2 stroke 45 degree V type, with an 8+1⁄2 by 10 in (216 by 254 mm), bore by stroke, giving 567 cubic inches (9.29 L) displacement per cylinder. A D.C. generator provides power to four motors, two on each truck, in a B-B arrangement. The SW1, like most EMD switchers, use the AAR type A switcher truck. EMC/EMD has built all its own components since 1939.
A number of changes were made to the SW1 over its production life. Internally, the post-war locomotives used the 567A engine.
Externally, the two center cab windows over the hood, which were curved to follow the roofline originally, became flat-topped after mid-1950. Another external difference is the taper of the hood to the cab, which was a two-stage taper in earlier units but became a single taper in later production. Very early locomotives were delivered with a stubby exhaust stack, but this did not lift the diesel exhaust sufficiently clear of crew visibility. All later units were delivered with EMD's standard conical switcher stack, while early units were generally modified with taller stacks too. Early locomotives had a single large headlight, while later had twin sealed-beam headlights.
- There were 7 units built as EMD demonstrators: #152 (to Scullin Steel #6), 700 (to Manufacturers' Junction Railway #7), 755 (to Inland Steel #51), 804 (to Southern Pacific Railroad #1000, pictured above), 905 (to Central of Georgia #1), 906 (to Western Pacific Railroad #501), 911 (to Great Lakes Steel #11)
- Owego and Harford Railway was still operating one SW1 for switching duties in their yard as of 2010, sitting derelict in a railyard in Owego, NY, as of 2019
- As of 2013, Amtrak still has one SW1 on their roster. #737 is used for switching chores at the Wilmington Delaware shops.
- As of 2021, Metra commuter rail rosters one SW1. It is used for Yard Service and power on work trains on the Metra Electric and Rock Island lines. It was originally built in 1945 for the Rock Island. Metra used to operate a second SW1, built in 1939, but sold it in June 2021 via online auction for $45,000 due to an internal engine failure. The unit built in 1939 was rumored to be one of the oldest operating diesels in Illinois and the oldest operating locomotive in the U.S. that was not preserved.
- Andersen Windowalls 3110 is preserved in operational condition at the Minnesota Transportation Museum It was previously Norfolk and Western Railway 3110 and originally Wabash Railroad 110, built in June 1949.
- Arkansas–Oklahoma Railroad 536 is in operational condition and in regular freight service. It was previously Chicago, Rock Island and Pacific 536 and is painted in a Rock Island inspired paint scheme.
- Baltimore and Ohio 8408 is preserved at the Wilmington and Western Railroad in operational condition.
- Black River and Western Railroad Lehigh Valley 112, is preserved on the BR&W in operational condition. And PRR 9206 preserved and in service.
- Boston and Maine 1109 is preserved at the Railroad Museum of New England.
- BRMX 1849, built as Boston and Maine 1113, is preserved at the Berkshire Scenic Railway, in Lenox, MA.
- Cargill 6751, built in 1940 with construction number 1111, was one of the first SW1s that Electro-Motive built. After buying the unit, the Baltimore and Ohio Railroad (B&O) initially numbered the locomotive as No. 213, but subsequently changed the number to 8413. Leased by the Washington and Old Dominion Railroad in 1968, B&O 8413 was one of the last locomotives to operate on the W&OD before the railroad closed during the same year. After several transfers of ownership, the locomotive was acquired by Cargill, becoming Cargill No. 6751. Cargill moved the locomotive to Ogden, Utah in 1993 for use in the company's Globe Mill. Following Cargill's donation of the locomotive in 2010, the Utah Central Railway and the Union Pacific Railroad delivered it on May 21, 2011, to the Utah State Railroad Museum for display at Union Station in Ogden.
- Commonwealth Edison 15 is preserved at the Illinois Railway Museum. This unit is in operating condition and is one of the most frequently used diesels on the property.
- Heart of Dixie 904, built as Memphis Union Station 10, is preserved at the Heart of Dixie Railroad Museum.
- Holly Sugar 1, the first SW1 built by EMC in 1939 is now preserved at the California State Railroad Museum in Sacramento, California. Built as Southern Pacific Lines 1000, the locomotive worked for the SP until its retirement in the 1970’s, then was sold to Holly Sugar and renumbered to 1. The museum donation was a coordinated effort between the museum, the Pacific Coast Chapter of the Railway and Locomotive Historical Society and Spreckels Sugar (the locomotive's last owner).
- Louisville & Nashville 13 is on display at the Foley Railroad Museum in Foley, AL.
- Milwaukee Road 1626 is preserved at the Milwaukee Road Heritage Center. It was formerly Northern States Power X-5, Ex-Burlington Northern 79, Exx- Chicago Burlington & Quincy 9137. Built in June 1939, the locomotive is in running condition, with its original Electro-Motive Division 6-567B-1 Prime Mover.
- Monon Railroad 50, the first diesel locomotive owned by the Monon, is leased to the Hoosier Valley Railroad Museum. It was damaged in the move to the new home of the Indiana Transportation Museum in Logansport, Indiana. ITM also had Milwaukee Road 1613, but it was scrapped in July 2018. The locomotive was moved from Logansport, Indiana to the Hoosier Valley Railroad Museum in North Judson, Indiana in April 2021, where it will be repaired and will join the HVRM's fleet of vintage diesel locomotives.
- New York Central 705, built as Louisville and Nashville 14, is preserved in operational condition at the Adirondack Scenic Railroad.
- Northern States Power 4 is preserved in operational condition at the Gopher State Railway Museum. It was originally built as CB&Q 9146 in May 1940.
- Peabody Coal Company 470 (Former Delaware, Lackawanna and Western #436) is on static display at the Museum of the Coal Industry in Lynnville, Indiana.
- Pennsylvania Railroad 9206 is preserved in operational condition on the Black River and Western Railroad.
- Pennsylvania Railroad 9408 is preserved in operational condition at the Railway Museum of Greater Cincinnati.
- Pere Marquette Railway 11 is preserved at the Baltimore & Ohio Railroad Museum, in Baltimore, MD, in operating condition at last report.
- Portland Traction Company 100 is preserved in operational condition at the Oregon Rail Heritage Center.
- Sacramento Northern 402, originally built as Western Pacific 502, is preserved at the California State Railroad Museum.
- SMS Rail Service 9423, former Pennsylvania Railroad 9423, is in storage in Bridgeport, NJ.
- Southern Pacific Lines 1006 is preserved in operational condition, restored to its as-built appearance. It resides at the Southern California Railway Museum (formerly known as the Orange Empire Railway Museum). 
- Western Pacific Railroad 501, originally built as EMC demonstrator 906, is preserved at the Western Pacific Railroad Museum at Portola, CA. This locomotive was the Western Pacific's first diesel-electric engine.
- Used locomotive dealer/lessor Western Rail, Inc. owns WRIX 1001 (built 06/1949 as NYC # 609 (2nd), later renumbered NYC 8435, PC 8435, CR 8435, GE Sayre Repair Shop # 2, IRLX 1006, IRLX 1001, WCTR 1001). WRIX 1001 currently resides on the Rogue Valley Terminal Railroad in White City, Oregon awaiting shipment to Western Rail - Airway Heights, Washington later in 2018.
- Wilmington and Western Railroad 114, built as Lehigh Valley 114, is preserved and operates tourist trains on the W&W.
- The Zanesville & Western Scenic Railroad 8599, former PRR 5999, operations excursions on its scenic line in Fultonham, Ohio.
- Dura-Bond (former owner of Turtle Creek Industrial Railroad) operates 462 at its pipe mill in McKeesport, PA. It is well maintained and operates as a switcher on about 7 miles of private track.
- Schafer, Mike (1998). Vintage diesel locomotives. Osceola, WI: Motorbooks International. pp. 22–25. ISBN 0-7603-0507-2. OCLC 38738930.
- Pinkepank, Jerry A (1973). The Second Diesel Spotter's Guide. Kalmbach Books. pp. 10, 26, 35. LCCN 66-22894.
- Ross, David, ed. (2003). The Encyclopedia of Trains and Locomotives. p. 264. ISBN 978-0-7607-9679-5.
- Pinkepank, Jerry A (1973). The Second Diesel Spotter's Guide. Kalmbach Books. p. 35. LCCN 66-22894.
- "Tulsa-Sapulpa Union Railway". American-Rails.com. Retrieved June 24, 2021.
- "SWITCH LOCOMOTIVE - govdeals.com". www.govdeals.com. Retrieved 2021-07-10.
- "Rolling Stock of the Utah State Railroad Museum: Cargill 6751: SW1". Utah State Railroad Museum: Spencer S. Eccles Rail Center. Ogden, Utah: Union Station. 2016. Archived from the original on 2017-01-27. Retrieved 2017-01-27.
- Harwood, Herbert Hawley, Jr. (2000). Rails to the Blue Ridge: The Washington and Old Dominion Railroad, 1847–1968 (3rd ed.). Fairfax Station, Virginia: Northern Virginia Regional Park Authority. p. 137. ISBN 0615114539. OCLC 44685168 – via Google Books. .
- "Museum Projects". www.lynnvillecoalmuseum.org. Retrieved 2017-02-25.
- Dorin, Patrick C. (1972). Chicago and North Western Power. Burbank, California: Superior Publishing. p. 96. ISBN 0-87564-715-4.
- Pinkepank, Jerry A. (1973). The Second Diesel Spotter's Guide. Milwaukee, Wisconsin: Kalmbach Publishing. ISBN 978-0-89024-026-7.
- (July 2005), "Preservation Briefs", Trains Magazine, p. 71.
- TrainWeb.com. The Unofficial EMD homepage. Retrieved on January 7, 2005. Contains fairly complete builders' records for early EMD production.
- Andersen Windows 3110. Retrieved on December 7, 2012
- EMD Product Reference Data Card dated January 1, 1959 has the 567AC engine data used in the as-built roster.
- Media related to EMD SW1 locomotives at Wikimedia Commons