EMD SW7 & SW9

By the late 1940s, EMD had just about perfected the small diesel switcher. The SW7, introduced in 1949, was the company’s logical next step after the NW2. It kept the proven 1,200hp rating but sat on a slightly longer frame with cleaner lines and the latest refinements to EMD’s dependable 12-567 prime mover. Between 1949 and early 1951, 489 SW7s were built along with 30 cow-and-calf TR4 sets, most from EMD’s Cleveland plant. They went to work everywhere from big-city terminals to small-town branch lines, quickly proving themselves as smooth, reliable and deceptively powerful machines.

Maine Central SW9 334 is seen at Bangor, Maine, in April 1973. © K. Landess / TMB Collections

The SW9 followed in late 1950 and remained in production until 1953. Externally, it looked much the same, but beneath the hoods sat the improved 12-567B engine, revised cooling arrangements and a few detail differences, notably the absence of the upper hood vents seen on the SW7. A total of 786 were built in the United States, with another 29 constructed by General Motors Diesel in Canada. These locomotives often worked far beyond the yard limits, their compact size and surefooted pulling power making them favourites for branch work and short-haul freights.

Together, the SW7 and SW9 formed the backbone of EMD’s second generation of switchers, bridging the gap between the early wartime designs and the later, more refined SW1200 that followed in 1954. They were workaday locomotives, built with that characteristic EMD balance of simplicity, strength and understated style, the sort of engine that quietly got the job done day after day.

Bangor & Aroostook

Bangor & Aroostook EMD SW9 No. 36 stands at Oakfield, Maine, in 1984, wearing the railroad’s red, white, and black scheme. The locomotive shows heavy weathering from yard service, with exhaust staining along the hood and worn paintwork typical of hard-working switchers in the later years of BAR operations. © Greg F. Brewer
ClassNo.BuiltSerialLiveriesNotesPhotographsModelling
SW930Mar 195114103Ex Pittsburgh & Lake Erie No. 8935. Purchased 1972. Sold 1975.
SW931Mar 195114102Ex Pittsburgh & Lake Erie No. 8934. Purchased 1972. Sold 1975.
SW932Mar 195114104Ex Pittsburgh & Lake Erie No. 8936. Purchased 1972.
SW933Mar 195114099Ex Pittsburgh & Lake Erie No. 8931. Purchased 1972.
SW934Mar 195114106Ex Pittsburgh & Lake Erie No. 8938. Purchased 1972.
SW935Mar 195114101Ex Pittsburgh & Lake Erie No. 8933. Purchased 1972.
SW936Mar 195114108Ex Pittsburgh & Lake Erie No. 8940. Purchased 1972.
SW937Feb 195114110Ex Pittsburgh, Chartiers & Youghiogheny No. 3. Purchased 1972. Sold 1975.
SW938Dec 195217224Ex Pittsburgh, Chartiers & Youghiogheny No. 4. Purchased 1972. Sold 1975.
SW939Sep 195318710Ex Pittsburgh, Chartiers & Youghiogheny No. 5. Purchased 1972. Sold 1975.

Boston & Maine

Boston & Maine EMD SW9 No. 1224 performs yard switching duties at East Deerfield, Massachusetts, on 10 October 1983. The locomotive works long cuts of boxcars in the yard, typical of the busy classification work handled at this major B&M facility. © Bud Kula

Maine Central

The Maine Central’s EMD SW7s were equipped with road-style multiple-unit control and painted in full road colours, as they were never intended for yard work. They entered service at Waterville in September 1950, breaking in on mainline locals before moving to Bartlett within a month. Joined by SW9 334 eleven months later, the foursome took over local and helper operations on the Mountain, replacing Ten-wheelers on Mixed 377/378 to Beecher Falls, Mikados in helper service, and working locals to Rigby and Gilman in their spare time. When SW9 335 arrived in January 1954, the last 2-8-2 in standby helper duty was sent to Waterville, completing the dieselisation of the Mountain Sub. The local schedule kept the handsome switchers busy: Bartlett local RZ-2 departed Rigby at 9am on Monday, Wednesday and Friday, returning at 8am the following morning with a single SW. A pair would be called around 3am to assist RY-2.

Maine Central SW9 335 at Bangor, ME on 19 August 1976. © Frank Szachacz

Pine green with gold band. In the summer of 1984 they were renumbered to MEC 933 and MEC934 in order to avoid conflict with Boston & Maine’s former Conrail GP40-2s, and then became Springfield Terminal 1432 and 1433.

Maine Central SW7 No. 331 (built 1950) and SW9 No. 335 (built 1953), both in maroon and gold, wait at the Bangor engine house for either the Bucksport run or the Old Town switcher, with GP7 No. 562 in the background. Photograph taken before 1971. © Dwight Mitchell
Maine Central SW7 332 and an identified sister a Bangor, Me. InJuly 1970. © D.S.Hutchinson Collection
Maine Central SW9s 334 & 335 crossing the Penobscot River after working the Bucksport job around 1971. © Richard Glueck
Maine Central SW7 332 and SW9 334 are seen at Bangor, Maine, in June 1973. © G. Turnbull
Maine Central EMD SW7 No. 332 stands at Bangor Yard on 23 August 1978, wearing the later pine tree scheme with bold yellow numerals and stripe. Built for yard and transfer work, locomotives of this class were regular performers on local turns such as the Bucksport jobs through the late 1960s and mid-1970s. © Bill Rogerson
Maine Central EMD SW7 No. 933, recently renumbered from No. 333, switches freight cars at Waterville, Maine, in July 1984 following the Guilford Transportation Industries takeover. The locomotive is equipped with class lights and multiple-unit connections, reflecting its use in both yard and branch line service. © Mitch Kennedy
Maine Central SW9 335 is seen at Bangor, Maine, in May 1979. © K. Landess / TMB Collection
Maine Central SW9 335 at Mechanicville, New York, in October 1983. © Alan S. Gaines
Under the Guilford Transportation flag, Maine Central SW9 934 is seen at Mechanicville, New York, in September 1984. © K. Landess Collection
ClassNo.BuiltSerialLiveriesNotesPhotographsModelling
SW7331
(931)		Sep 195012370Delivered in Red with Yellow Stripes, retained until at least Dec 1975. Switcher Green by Jan 1977.MU initially on rear only, soon added to front. Renumbered to 931.RR Picture Archives, RR Picture Archives
SW7332 (932)Sep 195012371Delivered in Red with Yellow Stripes, retained until at least Oct 1964. Switcher Green by Jan 1977.MU initially on rear only, soon added to front.RR Picture Archives
SW7333
(933)		Sep 195012372Delivered in Green with Yellow Stripes, retained until at least Jan 1975. Switcher Green by Jan 1976.MU initially on rear only, soon added to front. Renumbered to 933. RR Picture Archives, RR Picture Archives
SW9334
(934)		Aug 195114754Delivered in Red with Yellow Stripes, retained until at least Oct 1980. Switcher Green by Jun 1981.Renumbered to 934.RR Picture Archives, RR Picture Archives
SW9335
(935)		Dec 195319044Delivered in Green with Yellow Stripes, retained until at least Aug 1976. Switcher Green by ?Renumbered to 935.RR Picture Archives, RR Picture Archives
Maine Central SW7 932 (formerly 332) in Switcher Green livery on a Boston & Maine local freight ED-5 at Erving, Mass. on 15 February 1987. © D.S. Hutchinson Collection

Modelling

  • Broadway Limited 3938 N EMD SW7, Paragon4 DCC Sound, Maine Central #332 (Trainworld)
  • Broadway Limited 3939 N EMD SW7, Paragon4 DCC Sound, Maine Central #333 (Trainworld)

More Information

  • Marre, Louis. Diesel Locomotives: The First 50 Years – A Guide To Diesels Built Before 1972 (Railroad Reference Series No. 10). Kalmbach Books, 1995, pp. 30-32.
  • Melvin, George F. Maine Central in Color Volume 3. Morning Sun Books, 2008, pp.10-11, 31.
  • Robertson, E. B. (1978). Maine Central Diesel Locomotives. Westbrook, USA: Edwin B. Robertson, pp. 24-27.