View source for Pennsylvania Railroad class P5

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{{Infobox Locomotive
|name = PRR P5/P5a
|powertype = Electric
|image = PRR P5a 4761.jpg
|imagesize = 300px
|caption = PRR P5a #4761
|builder = PRR [[Altoona Works]] (13)<br>[[Baldwin Locomotive Works|Baldwin]]-[[Westinghouse Electric (1886)|Westinghouse]] (54)<br>General Electric (25)<ref name="pennsypower" />
|builddate=1931–1935 
|totalproduction = 92
|whytetype = [[4-6-4]]
|aarwheels = [[AAR wheel arrangement#2-C-2|2-C-2]]
|uicclass = [[2′{{notatypo|Co|2′|reason=prevent appearance in chem lists}}]]
|gauge= {{Track gauge|56.5in|allk=on}}
|leadingdiameter = {{convert|36|in|0|abbr=on}}<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|driverdiameter = {{convert|72|in|0|abbr=on}}<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|trailingdiameter = {{convert|36|in|0|abbr=on}}<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|wheelbase = {{convert|49|ft|10|in|abbr=on}} (total);<br>{{convert|20|ft|2|abbr=on}} (rigid)<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|length = {{convert|62|ft|abbr=on}}<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|width = {{convert|10|ft|6|in|abbr=on}} (P5, P5a, P5b);<ref name="p5diagram" /><ref name="p5bdiagram" /><br>{{convert|10|ft|8.25|in|2|abbr=on}} (P5a (modified))<ref name="p5amoddiagram" />
|height = {{convert|15|ft|2|abbr=on}} over locked-down pantographs<ref name="p5diagram" /><ref name="p5bdiagram" /><ref name="p5amoddiagram" />
|axleload = {{convert|74000|lb|kg t|abbr=on}} (P5, P5a);<ref name="p5diagram" /><br>{{convert|77800|lb|kg t|abbr=on}} (P5b);<ref name="p5bdiagram" /><br>{{convert|77000|lb|kg t|abbr=on}} (P5a (modified))<ref name="p5amoddiagram" />
|weightondrivers = {{convert|220000|lb|kg t|abbr=on}} (P5, P5a);<ref name="p5diagram" /><br>{{convert|444700|lb|kg t|abbr=on}} (P5b, all wheels driven);<ref name="p5bdiagram" /><br>{{convert|229000|lb|kg t|abbr=on}} (P5a (modified))<ref name="p5amoddiagram" />
|locoweight = {{convert|392000|lb|kg t|abbr=on}} (P5, P5a);<ref name="p5diagram" /><br>{{convert|444700|lb|kg t|abbr=on}} (P5b);<ref name="p5bdiagram" /><br>{{convert|394000|lb|kg t|abbr=on}} (P5a (modified))<ref name="p5amoddiagram" />
|electricsystem = 11 [[Volt|kV]] [[Alternating current|AC]] @ 25 [[Hertz|Hz]] [[Overhead line|Catenary]]
|collectionmethod = [[Pantograph (rail)|Pantograph]]
|tractionmotors = 6× {{convert|625|hp|adj=on|abbr=on}} AC motors;<ref name="p5diagram" /><ref name="p5amoddiagram" /> plus 4× {{convert|375|hp|adj=on|abbr=on}} motors on the trucks on P5b<ref name="p5bdiagram" />
|transmission = AC current fed via transformer [[tap changer]]s to paired motors geared (25:97) to quill drives on each driving axle;<ref name="p5diagram" /><ref name="p5amoddiagram" /> plus single motors geared to driving axles on end trucks on P5b (gear ratio: 17:50)<ref name="p5bdiagram" />
|operator=Pennsylvania Railroad
|fleetnumbers=4700–4791
|preservedunits=4700
|disposition= One P5 prototype preserved; rest scrapped.
}}
The [[Pennsylvania Railroad]]'s class '''P5''' comprised 92 mixed-traffic [[electric locomotive]]s constructed 1931–1935 by the PRR, [[Westinghouse Electric (1886)|Westinghouse]] and [[General Electric]].<ref name="pennsypower">{{Staufer-Pennsy|page=298}}</ref> Although the original intention was that they work mainly passenger trains, the success of the [[PRR GG1|GG1]] locomotives meant that the P5 class were mostly used on freight. A single survivor, prototype #4700, is at the [[National Museum of Transportation]] in [[St Louis, Missouri]].

They had an [[AAR wheel arrangement]] of [[AAR wheel arrangement#2-C-2|2-C-2]], or [[2′{{notatypo|Co|2′|reason=prevent appearance in chem lists}}]] in the [[UIC classification]] system — three pairs of driven wheels [[rigid-framed electric locomotive|rigidly mounted to the locomotive]], with a two-axle unpowered [[bogie|truck]] at each end. This is an equivalent to a 4-6-4 in the [[Whyte notation]].<ref name="p5diagram" >{{cite web
 |author    = Pennsylvania Railroad
 |url       = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=p5_p5a.gif&sel=ele&sz=sm&fr=
 |title     = P5 & P5a
 |work      = PRR Locomotive Diagrams
 |access-date      = 2008-08-29
}}</ref><ref name="p5bdiagram" >{{cite web
 |author    = Pennsylvania Railroad
 |url       = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=p5b.gif&sel=ele&sz=sm&fr=
 |title     = P5b
 |work      = PRR Locomotive Diagrams
 |access-date      = 2008-08-29
}}</ref><ref name="p5amoddiagram" >{{cite web
 |author    = Pennsylvania Railroad
 |url       = http://prr.railfan.net/diagrams/PRRdiagrams.html?diag=p5b.gif&sel=ele&sz=sm&fr=
 |title     = P5a (modified)
 |work      = PRR Locomotive Diagrams
 |access-date      = 2008-08-29
}}</ref> The PRR did not have any [[4-6-4]] steam locomotives, so the P5s were the only 4-6-4 type locomotives owned by the PRR.

The first P5s were built with [[Boxcab|box cabs]].  A grade crossing accident in which the crew were killed led to the substitution of a central cab to give better crash protection, a streamlined steeple type, in later production, a design which  was also applied to the GG1.

{| class="wikitable sortable"
|+Table of P5 locomotive production
! Year !! Builder !! Bodystyle !! Road numbers !! Notes
|- style=text-align:center
| 1931 || Altoona || rowspan=4 | Boxcab || 7898-7899 || Class P5, Renumbered 4700 & 4791 respectively in 1933
|- style=text-align:center
| rowspan=2 | 1932 || Westinghouse <!-- || Boxcab --> || 4701–4732 || 4702 rebuilt to P5b in 1937
|- style=text-align:center
| <!-- 1932 || --> General Electric <!-- || Boxcab --> || 4755–4774 || 4770 rebuilt as Modified in 1945
|- style=text-align:center
| 1933 || Westinghouse <!-- || Boxcab --> || 4733-4742 || 
|- style=text-align:center
| 1934 || Altoona || rowspan=4 | Modified || 4780 || 
|- style=text-align:center
| rowspan=3 | 1935 || Westinghouse <!-- || Modified --> || 4743–4754 || 
|- style=text-align:center
| <!-- 1935 || --> General Electric <!-- || Modified --> || 4775-4779 || 
|- style=text-align:center
| <!-- 1935 || --> Altoona <!-- || Modified --> || 4781-4790 || 
|-
|}

When the GG1s were put in passenger service, the P5s were regeared and used in freight service for many years.  The last of the class was withdrawn from service in April 1965.<ref name="prr1965">{{cite web
 |author     = Pennsylvania Railroad Technical and Historical Society
 |title      = PRR Chronology 1965
 |url        = http://www.prrths.com/Hagley/PRR1965%20June%2004.wd.pdf
 |date=August 2004
 |access-date = 2008-08-30
}}</ref>
__NOTOC__
==P5 prototypes==

Two prototype locomotives were outshopped from the PRR's Altoona Works in 1931.<ref name="pennsypower" />  They were essentially the [[PRR O1|PRR's 2-B-2 O1 design]] lengthened by adding another pair of driving wheels; while the O1 was an "electric Atlantic" equivalent to the [[PRR E6|E6s]] steam locomotive, the P5 was an "electric Pacific" designed to match or better the performance of the PRR's ubiquitous [[PRR K4s|K4s Pacifics]].

These prototypes had electrical equipment from both Westinghouse and General Electric; the design was by both companies and the PRR's electrical department, and the equipment from each manufacturer was identical.

==P5a production locomotives==

Orders were placed for 90 production locomotives classified '''P5a''' due to minor changes from the prototypes (notably, larger traction motor blowers).<ref name="pennsypower" />  Production was split between General Electric and Westinghouse; the GE examples were assembled at GE's [[Erie, Pennsylvania]] facility, still a locomotive assembly plant today, while final assembly for the Westinghouse order was subcontracted to the [[Baldwin Locomotive Works]].

==P5a (modified) steeplecabs==

A fatal [[grade crossing]] accident on the New York Division confirmed traincrews' concerns about safety when the crew were killed after colliding with a truckload of apples.<ref name="pennsypower" />  A redesign was undertaken, giving the locomotives a central cab, raised higher, with narrower-topped, streamlined "noses" to the locomotive to enable the crew to see forward.  The final 28 locomotives were built to this design, which was not given a separate class designation since it was mechanically and electrically identical; they were called class '''P5a (modified)''', and colloquially '''Modifieds'''.<ref name="pennsypower" />

[[File:PRR P5a mod.jpg|thumb|P5a (modified) #4780]]
Documentation published in 2010 disproved the decades long belief that the modified P5's new shell design came first and was then applied to the [[PRR GG1|GG1]], [[PRR R1|R1]], and eventually the [[PRR DD2|DD2]]. Instead, it was revealed that the GG1 project, under the direction of industrial designer Donald R. Dohner, was the first to receive the center cab design, and that soon afterward it was applied to the R1 and P5.<ref >Wayt, Hampton C. (Fall 2010). "Update on the GG1's genesis". Classic Trains (Kalmbach) 11 (3): 86–87.</ref>

The Modified units (along with the R1 and prototype GG1) were built with riveted carbodies. However, unit #4770, rebuilt to a Modified appearance in January 1945 after being wrecked in February 1944,<ref >{{Cite news
  |title=2 Killed as 90 Car Freight Speeds Past Flagman and Plows Into Standing train
  |newspaper=[[Philadelphia Inquirer]]
  |date=February 14, 1944
  |page= 1
}}</ref><ref >{{Cite book|title=Investigation no. 2774 The Pennsylvania Railroad Company report in re accident near Roxton, Pa., on February 13, 1944|author=Interstate Commerce Commission|oclc=947002343}}</ref> differed from previous Modifieds in having an all-welded carbody, the type of construction famously utilized in the production run of the GG1.<ref >{{cite book
  |last=Volkmer  |first=William D.
  |title=Pennsy Electric Years
  |year=1991
  |publisher=Morning Sun Books  |location=Edison, New Jersey
  |isbn=1-878887-01-7
  |pages=26–27
}}</ref>

==P5b experiment==

In October 1937, P5a #4702 was rebuilt with motors in its trucks to become the only locomotive in subclass '''P5b'''. Each truck axle was given a {{convert|375|hp|adj=on}} motor,<ref name="p5bdiagram" /> adding {{convert|1500|hp|abbr=on}} to give a total power output of {{convert|5250|hp||abbr=on}} and a wheel arrangement of B-C-B or Bo′CoBo′. The main drivers had used {{illm|double traction motor{{!}}double traction motors|de|Zwillingsmotor}} on each axle, but the trucks were a single motor per axle. This modification also meant that locomotive's entire weight was carried on driven wheels. Despite these advantages the experiment was not repeated, however #4702 continued in its modified form. 

Visually, the class P5b could be distinguished from a boxcab P5a by having a lower row of ventilation grilles on the sides of the superstructure, and by having outside brake cylinders on the trucks.<ref name="pennsypower" />

==See also==
* [[PRR locomotive classification]]

==References==
{{Reflist}}

{{GE electrics}}
{{WH electrics}}
{{PRR locomotives}}

[[Category:Baldwin locomotives]]
[[Category:General Electric locomotives]]
[[Category:Pennsylvania Railroad locomotives|P5]]
[[Category:11 kV AC locomotives]]
[[Category:4-6-4 locomotives]]
[[Category:Westinghouse locomotives]]
[[Category:Electric locomotives of the United States]]
[[Category:Railway locomotives introduced in 1931]]
[[Category:Standard gauge locomotives of the United States]]