EMD SW / SW1, Class ES6

The EMD SW1 is a 600-horsepower 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 V6 form. 661 locomotives of this design were built, no SW1s were built after March 1943 until production started again in September 1945.

Like most long-running locomotive models, a number of changes were made to the SW1 over its production life. Internally, the post-war locomotives were somewhat improved, and used the 567A engine.

One easily spotted change is the shape of the two center cab windows over the hood, which were curved to follow the roofline originally, but became flat-topped after mid-1950. Another easily seen 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.

The SW1 appears very similar to its SC and SW predecessors, but has only a single stack instead of two, a significantly shorter hood and a larger rear platform, no small louvers on the front top hood sides, and a large grille instead of lifting vents on top of the hood front. The sandbox in front of the radiator is somewhat smaller on the SW1.

Compared to later EMD switchers, the SW1 has a much shorter hood, large platforms at each end, a single exhaust stack, and a large 'satchel' type sandbox.

From http://yardlimit.railfan.net.

The SW1 is characterized by the single exhaust stack, front sand box and the extra deck space behind the cab. Later phases had the tall exhaust stack and a straight hood to cab transition.

EMD NW2, Class ES10

The EMD NW2 is a 1,000 hp (750 kW), B-B switcher locomotive manufactured by General Motors Electro-Motive Division of La Grange, Illinois. The NW2 was manufactured from February 1939 to December 1949, and 1145 were produced – 1121 for the U.S., and 24 were exported to Canada. Starting in late 1948 the NW2s were manufactured in EMD's Plant #3 in Cleveland, Ohio. The 1,000 hp (750 kW) was achieved by using a 12-cylinder, model 567, and later, a model 567A engine. In addition, 3 TR cow-calf paired sets, 36 TR2 cow-calf paired sets, and 2 TR3 cow-calf-calf sets were produced. The TR sets were built prior to World War II and the TR2 and TR3 sets were built postwar.

Distinguishing features include two stacks in the middle of the hood, a half-height radiator grille, no sand box on the front platform, and no small louvers at the top front corners of the sides of the hood. The predecessor of the NW2 was the NW1. The "N" in NW1 stands for the nine in nine hundred hp (670 kW). The "W" in both models stands for welded frame.

As an experiment, for passenger switching, ES10 #9175 was painted Tuscan Red.

From http://yardlimit.railfan.net.

The Phase I to IV NW2 is characterized by the stepped hood to cab transition.

The Phase V NW2 is characterized by the straight hood to cab transition and the smaller NW2 opening.

EMD SW7 / SW9 / 1200, Class ES12 / ES12m

The EMD SW7 was a diesel switcher locomotive built by General Motors Electro-Motive Division between October 1949 and January 1951. It was powered by a V12 567A engine developing 1,200 horsepower (895 kW). 489 SW7 locomotives were produced. The majority of the SW7s were built by EMD Plant #3 in Cleveland, Ohio. In addition, 15 TR4 cow-calf paired sets were produced.

An EMD SW9 is a diesel switcher locomotive built by General Motors Electro-Motive Division between November 1950 and December 1953. Additional SW9s were built by General Motors Diesel in Ontario Canada from December 1950 to March 1953. Power was provided by an EMD 567B 12-cylinder engine, producing 1,200 horsepower (895 kW). Starting in October 1953 a number of SW9s were built with the 567BC engine and in December 1953 Weyerhaeuser 305 was built with a 567C engine.

An EMD SW1200 is a diesel switcher locomotive built by General Motors Electro-Motive Division between January 1954 and May 1966. Power is provided by an EMD 567C 12-cylinder engine which generates 1,200 hp (895 kW). Late SW1200s built in 1966 were built with the 567E 12-cylinder engine. Additional SW1200 production was completed by General Motors Diesel in Ontario, Canada, between September 1955 and June 1964.

SW1200 7921 was known assigned to Lewistown at some point, per photo on page 132 of "Lewistown and the Pennsylvania Railroad".

From http://yardlimit.railfan.net.

The SW7 has the same profile as the Phase V NW2 with a straight hood to cab transition and six louvered doors. The SW7 has the larger, full length, front intake opening while the Phase V NW2 has the smaller NW2 opening.

The SW9 and SW1200 are characterized by eight louvered doors, hood door latches and triangler frame gussettes. The later model SW1200 has open risers on the steps for draft gear inspection.