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 feet 8+1⁄2 inches (1,435 mm) Length 75 ft 10 in (23.11 m) Loco weight 378,000 lb (171 t) Prime mover ALCO 251C, (2) Engine type Four stroke diesel Aspiration Turbocharger Displacement 8,016 cu in (131.36 L) Cylinders V12, (2) Cylinder size 9 by 10+1⁄2 inches (230 mm × 270 mm) Transmission Voith hydraulic Loco brake Straight air Train brakes Air
Performance figures Power output 4,300 hp (3,200 kW) Tractive effort 95,000 lbf (420,000 N)
Career 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 unit 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. These hydraulic-drive diesels 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 scrap the C-643DHs in 1973.

Original Owners

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

References

• "ALCO 244 and 251 Diesel Engines". Pacific Southwest Railway Museum. Retrieved 20 February 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