ALCO S-2 and S-4
|ALCO S-2 and S-4|
|Type and origin|
|Builder||ALCO and MLW|
|Model||S-2 and S-4|
|Build date||S-2: August 1940
– June 1950|
S-4: June 1949 – August 1957
|Total produced||S-2: 1502, S-4: 797|
|AAR wheel arr.||B-B|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
S-4: AAR type A
|Wheel diameter||40 in (1,016 mm)|
|Wheelbase||30 ft 6 in (9.30 m)|
|Length||46 ft (14.02 m)|
|Width||10 ft 2 1⁄2 in (3.11 m)|
|Height||14 ft 6 in (4.42 m)|
|Locomotive weight||230,000 lb (100,000 kg)|
|Fuel capacity||635 US gal (2,400 L)|
|Prime mover||Alco 539T|
|Engine type||Four-stroke diesel|
|Displacement||1,595 cu in (26.14 L) per cylinder
9,572 cu in (156.86 L) total
|Generator||GE GT 553-A|
|Traction motors||(4) GE 731|
|Cylinder size||12 1⁄2 in × 13 in (320 mm × 330 mm)|
|Power output||1,000 hp (746 kW) @ 740 rpm|
|Tractive effort||57,500 lb (26,100 kg)|
|Locale||United States, Canada, Mexico, Australia|
The ALCO S2 and S4 were 1,000 horsepower (746 kW) switcher diesel-electric locomotives produced by ALCO and Canadian licensee Montreal Locomotive Works (MLW). Basically, the two locomotives differed only in trucks, with the S-2 using ALCO's own Blunt trucks, and the S-4 riding on standard AAR type A switcher trucks. Both were powered by ALCO 539 turbocharged, 6-cylinder diesels. The S-2 was built between August 1940 and June 1950, with a total of 1502 completed, while the S-4 was constructed between June 1949 and August 1957 (MLW until 1957) with total sales of 797. Canadian production of the S-4 started more than a year before U S production of the S-4. ALCO did not start building the S-4 until August 1950. A modified version, the S-7, was built by MLW only; 29 were built between June and August 1957.
The S-2 and S-4 are distinguishable externally from the very similar S-1 and S-3 660 hp (492 kW) switchers in that they have a larger exhaust stack with an oblong base and a larger radiator shutter area on the nose sides. The S-1/S-3 radiator shutter area is taller than it is wide, while the S-2/S-4 radiator area is wider. The larger stack is due to turbocharging. The carbody and cab of late S-2s are nearly indistinguishable from those of S-4s. Hence, a truck swap can cause many to misidentify a unit.
A few S4s are still in service on shortline railroads around the United States. Several more are preserved in US and Canadian railroad museums.
The Cooperstown and Charlotte Valley Railroad operates a pair of restored ex-Canadian National units. S4 #3051 and S7 #3052 are both in regular tourist passenger and maintenance of way service between Milford and Cooperstown, NY.
Muskogee, Oklahoma at the Three Rivers Museum a S-2 #63-138 sits outside in the back of the Midland Valley Station.
The Houston Railroad Museum in Houston, Texas have two S-2's; Ex Santa Fe, #2350 and Ex Houston Belt and Terminal, #14.
Louisville & Nashville rebuilt many of their Alco switchers with 12-567 EMD prime movers in an effort to standardize their switching fleet. One of these, S4 (or S4m as rebuilt) #2326 survives at Gerdau Ameristeel in Cartersville, GA. Ameristeel recently donated the locomotive to the Southeastern Railway Museum at Duluth, GA.
The Virginia & Truckee Railroad acquired an S-4 from PPL Montana in 2010. The locomotive is in operable condition & slowly being repainted to the railroad's diesel colors.
Class III railroad Toledo, Lake Erie, and Western owns four ALCO S-2 and S-4s. TLEW 62, a S-2 purchased in 2012, ex. Delray Cement 62, TLEW 112, a S-2 that was part of the original TLEW roster, now reduced to a parts unit as of 2010, TLEW 5109, a S-4, and the only operating ALCO on the line currently. 5109 recently was repainted into its original Chesapeake and Ohio colors in September 2013. TLEW 5109's horn was stolen during the repainting process. TLEW 9752, a S-4 of Penn Central and Pittsburgh & Lake Erie heritage, was not used much, and was eventually scrapped for parts in October 2010.
The North Alabama Railroad Museum in Huntsville, Alabama runs an S-2 in regular tourist excursions, Mercury and Chase #213. It also owns another S-2, Mercury & Chase #484, which is temporarily out of service due to repairs. They also have ex-Santa Fe #1534, which is an S-4.
San Francisco Bay Railroad, the short-line railroad for the Port of San Francisco, operates the #23 and #25 Alco S-2's from the San Francisco Belt Line Railroad.
- Dorin, Patrick C. (1972). Chicago and NorthWestern Power. Superior Publishing. p. 136. ISBN 0-87564-715-4.
- Pinkepank, Jerry A. (1973). The Second Diesel Spotter's Guide. Kalmbach Publishing Co., Milwaukee, WI. p. 224. ISBN 0-89024-026-4.
- Toppan, Andrew et al. Alco/MLW S-2 Roster. Retrieved on December 29, 2005.
- Toppan, Andrew et al. Alco/MLW S-4 Roster. Retrieved on December 29, 2005.
- Steinbrenner, Richard T. (2003). The American Locomotive Company: A Centennial Remembrance. On Track Publishers LLC, New Brunswick, NJ. ISBN 0-911122-07-9.