PRR DD1

PRR DD1
Power type	Electric
Builder	Altoona Works
Build date	1911
Total produced	66 (in 33 married pairs)
AAR wheel arr.	2-B+B-2
UIC classification	2′B+B2′
Gauge	4 ft 8 1⁄2 in (1,435 mm)
Leading wheel diameter	36 in (914 mm)
Driver diameter	72 in (1,829 mm)
Wheelbase	7 ft 5 in (2.26 m) between driving axles
Length	64 ft 11 in (19.79 m)
Width	9 ft 1 in (2.77 m)
Height	14 ft 8 in (4.47 m)
Weight on drivers	199,000 lb (90.3 tonnes)
Locomotive weight	313,000 lb (142.0 tonnes)
Electric system	650 V DC
Current collection method	Third rail
Traction motors	2 × 315-A 2,000 hp (1,500 kW)
Transmission	Resistance controlled DC current supplied to DC motors connected to the axles through Jackshaft and side rods
Top speed	85 mph (137 km/h)
Power output	4,620 hp (3,450 kW)
Tractive effort	65,500 lbf (291 kN)

The Pennsylvania Railroad's class DD1 were semi-permanently coupled pairs of third rail direct current electric locomotives built for the railroad's initial New York-area electrification. They operated between Manhattan Transfer and Pennsylvania Station in New York City, and from there to the coach yards at Sunnyside Yard in Queens, New York. Some also operated on the PRR-owned Long Island Rail Road's extensive third rail network. They had a wheel arrangement of 4-4-0+0-4-4 in the Whyte notation; in other words, two 4-4-0 locomotives coupled back-to-back. In the AAR wheel arrangement notation, this is described as 2B+B2. Each half-locomotive contained one large electric motor mounted in the body and driving via a jackshaft and side rods. Those electric motors gave the DD1 a potential top speed of 85 mph. The simplicity and reliability of these locomotives allowed it to outlast its potential replacement model, the PRR L5.

One pair, Nos. 3936 and 3937, is located in the Railroad Museum of Pennsylvania and was listed on the National Register of Historic Places.

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  Running gear and electrical equipment

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  Side-view drawing

See also

• PRR locomotive classification

References

• Staufer, Alvin (1962). Pennsy Power. Staufer. pp. 248–253. LOC 62-20878.