ALCO S1

ALCO S-1 and S-3

Mid-Continent Railway No. 7, an S-1, rests between trains on October 10, 2004

Type and origin Power type Diesel Builder American Locomotive Company Montreal Locomotive Works Build date April 1940–June 1950 (S-1) February 1950–November 1953 (S-3) Total produced 543 (S-1) 300 (S-3)

Specifications Configuration: ​  • AAR B-B Gauge 4 ft 8 1⁄2 in (1,435 mm) Trucks Blunt (S-1) AAR type A (S-3) Wheel diameter 40 in (1,000 mm) Minimum curve 50° Wheelbase 30 ft (9.14 m) Length 45 ft (14 m) Width 10 ft 2 1⁄2 in (3.112 m) Height 14 ft 4 3⁄8 in (4.378 m) Loco weight 199,000 lb (90,000 kg) Fuel capacity 635 US gal (2,400 L) Prime mover Alco 539 Engine type Four-stroke diesel Aspiration Natural Displacement 9,572 cu in (156.86 l) Generator GE GT 552-A Traction motors 4 × GE 731 Cylinders Straight 6 Cylinder size 12 1⁄2 in × 13 in (318 mm × 330 mm)

Performance figures Power output 660 hp (490 kW) Tractive effort 49,790 lb (22,580 kg)

Career Locale North America, Brazil, United Kingdom

The ALCO S-1 and S-3 were 660 horsepower (490 kW) switcher diesel-electric locomotives produced by ALCO and their Canadian subsidiary Montreal Locomotive Works (MLW). Basically, the two locomotives differed only in trucks, with the S-1 using ALCO's own Blunt trucks, and the S-3 riding on standard AAR type A switcher trucks. The S-1 was built between April 1940 and June 1950, with a total of 543 completed, while the S-3 was constructed between February 1950 and November 1953 (MLW until 1957) with total sales of 300. A modified version, the S-10, was built by MLW only; 13 were built between January and June 1958.

The S-1 and S-3 are distinguishable externally from the very similar S-2 and S-4 1,000 horsepower (750 kW) switchers in that they have a smaller exhaust stack with a round base and a smaller 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 smaller stack is due to the lack of turbocharging.

The S-10 is not externally distinguishable from later Canadian-built S-3 locomotives; it differed mostly in electrical equipment.

The S-1 and S-3 models were sold to an extensive list of railroads and industrial operators, as detailed below. Major owners of the S-1 included the New York Central Railroad (NYC), with 71 locomotives; the New Haven with 65 locomotives; the L&N with 45 locomotives; the C&NW, with 29 locomotives; and the Pennsylvania Railroad (PRR) with 27 locomotives. Major customers for the S-3 included the CP, with 101; the CN, with 49; the NYC, with 43 locomotives; the B&M, with 16; and the PRR, with 13. The MLW S-10 was sold only to the CP.