AT&SF No. 631, a Baldwin DS4-4-750, switching Train 1, the San Francisco Chief at Amarillo, TX.

(Roger Puta, courtesy Marty Bernard, railfan 44, Public domain, via Wikimedia Commons)



The Baldwin DS-4-4-750 was a four-axle 750 horsepower (560 kW) diesel-electric switcher locomotive built by the Baldwin Locomotive Works at it Eddystone, Pennsylvania factory between 1949 and 1951. It was a bridge between the 660 horsepower (490 kW) DS-4-4-660 and the S-8. It was the low power companion in Baldwin's catalog to their DS-4-4-1000 and the S-12.


Original owners

Railroad Quantity Road numbers Notes
Baldwin Locomotive Works (plant) 1 301 to Weyerhaeuser Timber Company 301 in 1956; became Texas South-Eastern 301, now R.J. Corman (Texas Line) 301
Baldwin Locomotive Works (demonstrators) 2 750–751 to Weyerhaeuser Timber Company 101–102
American Cyanamid Company 1 14
American Steel and Wire Company 1 20
Atchison, Topeka and Santa Fe Railway 9 525–533
California Western Railroad 2 51–52
Erie Railroad 4 386–389
Pennsylvania Railroad 24 5595–5618
Texas Mexican Railway 2 509–510
Warner Sand and Gravel 1 14 This locomotive is now on the Allentown and Auburn Railroad in Topton PA undergoing restoration
Youngstown Sheet and Tube 6 608–610, 700–702
Total 53

Page 40 of the Dolzall brothers book "Diesels from Eddystone" describes the DR-4-4-750 as a "Horsepower boost for a lagging seller." Baldwin dropped the DR-4-4-660 model and introduced the new 750 HP DR-4-4-750. The Atchison, Topeka & Santa Fe (AT&SF) purchased nine in August 1948 and 21 units were sold in 1949 to six different customers.



Type and origin
Power type: Diesel-electric
Builder: Baldwin Locomotive Works
Model: DS-4-4-750
Build date: July 1949 to February 1951
Total produced: 53
​• AAR B-B
• UIC B′B′
Gauge: 4 ft 8+1⁄2 in (1,435 mm)
Prime mover: 606NA
RPM range: 625 rpm max.
Engine type: Four-stroke diesel
Aspiration: Normally aspirated, solid injection
Displacement: 1,979 cu in (32.43 L) per cylinder; 11,874 cu in (194.58 L) total
Generator: DC generator
Traction motors: DC traction motors
Cylinders: Straight-6
Cylinder size: 12+3⁄4 in × 15+1⁄2 in (324 mm × 394 mm)
Transmission: Electric
Locomotive brake: Air
Train brakes: Air
Performance figures
Power output: 750 hp (559 kW)
Locale: North America