PRR DD2

Infobox Locomotive
name = PRR DD2
powertype = Electric

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builder = PRR Juniata Shops
builddate = February 7, 1938
totalproduction = 1
whytetype = 4-4-0+0-4-4
uicclass = (2'B)(B'2)
aarwheels = 2-B+B-2
weightondrivers = 296,000 lb (134,000 kg)
weight = 450,000 lb (204,000 kg)
tractiveeffort = 71,500 lbf (318 kN)
poweroutput = 5,000 hp (3,700 kW)
topspeed = 70 mph (113 km/h)
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)
leadingsize = 36 in (914 mm)
driversize = 62 in (1575 mm)
trailingsize = 36 in (914 mm)
electricsystem = 11 kV, 25 Hz overhead AC
collectionmethod = 2 roof-mounted pantographs (normally only one raised)
transmission = 4 × 1250 hp Westinghouse 428-A traction motor paired sets
railroad = Pennsylvania Railroad
railroadclass = DD2
numinclass = 1
roadnumber = 5800
firstrundate = 1938
locale = Wilmington, Delaware-Philadelphia, Pennsylvania, latterly Baltimore, Maryland area.
disposition = scrapped
scrapdate = September 1962
gauge = 4 ft 8½ in (1435 mm)

The Pennsylvania Railroad's class DD2 electric locomotive was a single prototype locomotive never placed into series production.cite book
author = Staufer, Alvin
title = Pennsy Power
id = LOC 62-20878
year = 1962
pages = 298
publisher = Staufer] 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.cite web
author = Pennsylvania Railroad Technical and Historical Society
title = PRR Chronology 1938
url = http://www.prrths.com/Hagley/PRR1938%20Aug%2004.wd.pdf
year = 2004
month = August
accessdate = 2008-08-27] The one locomotive produced was numbered #5800 and used in regular service until it was scrapped in September 1962.cite web
author = Pennsylvania Railroad Technical and Historical Society
title = PRR Chronology 1962
url = http://www.prrths.com/Hagley/PRR1962%20June%2004.wd.pdf
year = 2004
month = June
accessdate = 2008-08-27]

Design, construction and testing

On May 21, 1937, a meeting was held in Philadelphia to outline the design of a new electric freight locomotive. The meeting was attended by the PRR and Baldwin, as well as electrical suppliers General Electric and Westinghouse, and the transportation engineering firm Gibbs & Hill, who were consultants on the proposal to extend electrification to Pittsburgh. The locomotive being designed was what became the DD2.cite web
author = Pennsylvania Railroad Technical and Historical Society
title = PRR Chronology 1937
url = http://www.prrths.com/Hagley/PRR1937%20Aug%2004.wd.pdf
year = 2004
month = August
accessdate = 2008-08-27]

Technical details

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.,cite web
author = Pennsylvania Railroad
url = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=dd2.gif&sel=ele&sz=sm&fr=
title = DD2
work = PRR Locomotive Diagrams
accessdate = 2006-01-05 (simple drawing and specifications, for general reference by railroad staff).] 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

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