PRR DD2

PRR DD2

PRR DD2
Power type	Electric
Configuration	4-4-0+0-4-4
AAR wheel arr.	2-B+B-2
UIC classification	(2'B)(B'2)
Gauge	4 ft 8½ in (1435 mm)
Leading wheel size	36 in (914 mm)
Driver size	62 in (1575 mm)
Trailing wheel size	36 in (914 mm)
Length	72 ft 6¼ in (22.10 m)
Width	10 ft 6¼ in (3.21 m)
Height	15 ft 0 in (4.57 m) (pantographs locked down)
Weight on drivers	296,000 lb (134,000 kg)
Total weight	450,000 lb (204,000 kg)
Electric system	11 kV, 25 Hz overhead AC
Collection method	2 roof-mounted pantographs (normally only one raised)
Transmission	4 × 1250 hp Westinghouse 428-A traction motor paired sets
Top speed	70 mph (113 km/h)
Power output	5,000 hp (3,700 kW)
Tractive effort	71,500 lbf (318 kN)
Career	Pennsylvania Railroad
Class	DD2
Number in class	1
Number	5800
Locale	Wilmington, Delaware-Philadelphia, Pennsylvania, latterly Baltimore, Maryland area.
First run	1938
Disposition	scrapped

The Pennsylvania Railroad's class DD2 electric locomotive was a single prototype locomotive never placed into series production. It was intended as an improved and simplified GG1 for use on the planned, but never built, extension of the PRR's electrification west of Harrisburg, Pennsylvania. The one locomotive produced was numbered #5800 and used in regular service. Although the design specified either passenger gearing or freight gearing, the prototype was only ever used with freight gearing. Its wheel arrangement was 4-4-0+0-4-4 in the Whyte notation, or 2-B+B-2 in the AAR's system.

It had two frames, hinged together in the middle, with the driving wheels and motors mounted directly to each frame, two pairs per side. A swinging four-wheeled, unpowered truck was mounted at the outer end of each frame. The bodywork, mounted above, swivelled on mounts on each of the two main frames. This was an identical layout to the better-known GG1 electric locomotives, but with four driven axles instead of six. Each driven wheel had two electric motors, each rated at 625 hp, giving a total rating of 5,000 hp for the locomotive.

Although it had fewer driven wheels than the GG1, the total power output was slightly greater, thanks to newer and more powerful motors. Weight on the driven wheels was approximately 286,000 lb., compared to the GG1's 300,000 lb, meaning that in similar conditions of adhesion the GG1 was slightly at an advantage in terms of applying power to the rail, but the difference was not great. Styling was also similar to the GG1's.

References

• Staufer, Alvin (1962). Pennsy Power. Staufer, 298. LOC 62-20878. 
• Pennsylvania Railroad. DD2. PRR Locomotive Diagrams. Retrieved on 2006-01-05. (simple drawing and specifications, for general reference by railroad staff).

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