ALCO DH643

ALCO C-643DH
Southern Pacific #9152, formerly #9020.
Type and origin Power type Diesel-hydraulic Builder American Locomotive Company (ALCO) Order number S-3374 Serial number S-3374-01 – S-3374-03 Model DH-643 Build date September 1964 Total produced 3
Specifications Configuration: ​  • AAR C-C  • UIC C′C′ Gauge 4 ft 8+1⁄2 in (1,435 mm) Length 75 ft 10 in (23.11 m) Loco weight 378,000 lb (171,000 kg) Prime mover ALCO 12-251C, (x 2) Engine type V12 Four-stroke diesel, (x 2) Aspiration Turbocharger Displacement 8,016 cu in (131.36 L) Cylinders 12 (x 2) Cylinder size 9 by 10+1⁄2 inches (229 mm × 267 mm) Transmission Voith hydraulic Loco brake Straight air Train brakes Air
Performance figures Maximum speed 77 mph (124 km/h) Power output 4,300 hp (3,200 kW) Tractive effort 95,000 lbf (422.58 kN)
Career Operators Southern Pacific Railroad Numbers 9018–9020 (later 9150–9152; final 9800-9802) Locale North America Scrapped 1973

The ALCO C-643DH, also known as the Century 643DH, was a twin-engine diesel-hydraulic locomotive, the first diesel-hydraulic road switcher built in the United States. It had a C-C wheel arrangement and generated 4,300 horsepower (3,200 kW). Only three were built, all for Southern Pacific Railroad in 1964 (#9018–#9020). The Alco C-643DHs joined 21 Krauss-Maffei ML-4000 diesel-hydraulics already on the Southern Pacific's roster. They spent most of their service lives in the flat San Joaquin Valley in California.

Dissatisfaction over the poor performance of diesel-hydraulic locomotives, as well as their use of foreign-made components (the hydraulic transmission was of German Voith design), eventually led Southern Pacific to sell the three units for scrap in 1973. None were preserved.

Original owners

Railroad	Quantity	Road numbers	Notes
Southern Pacific Railroad	3	9018–9020	renumbered 9150–9152

See also

• List of ALCO diesel locomotives
• ALCO Century 855

References

• "ALCO 244 and 251 Diesel Engines". Pacific Southwest Railway Museum. Archived from the original on January 13, 2006. Retrieved February 20, 2006.
• Kirkland, John F. (1989). The Diesel Builders, Volume Two: American Locomotive Company and Montreal Locomotive Works. Interurban Press, Glendale, CA. ISBN 0-916374-81-5.
• Pinkepank, Jerry A. (1973). The Second Diesel Spotter's Guide. Kalmbach Publishing Co., Milwaukee, WI. ISBN 0-89024-026-4.
• Strapac, Joseph A. (1993). Southern Pacific Historic Diesels, Volume 2: Diesel-Hydraulic Locomotives. Shade Tree Books, Bellflower, CA. ISBN 0-930742-15-X.
• Strapac, Joseph A. (2001). Southern Pacific Historic Diesels, Volume 8: Alco Roadswitcher Locomotives. Shade Tree Books, Bellflower, CA. ISBN 0-930742-23-0.

External links

• Alco Six-Axle Centuries Roster
• Southern Pacific DH-643