View source for PKP class EW55

{{Short description|Electric multiple units produced by Pafawag in Wrocław}}
{{Infobox train
| name = EW55<ref name=":0">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=11–14}}</ref><ref name=":1">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=27–29}}</ref><ref name=":2">{{Cite book |last=Terczyński |first=Paweł |title=Atlas lokomotyw 2007 |publisher=Poznański Klub Modelarzy Kolejowych |year=2007 |isbn=978-83-920757-7-6 |location=Poznań |pages=85, 103 |language=pl}}</ref>
| image = EW55 (1).jpg
| stocktype = electric multiple unit
| manufacturer = [[Bombardier Transportation Polska|Pafawag]]
| assembly = [[Wrocław]], {{flag|Poland}}
| yearconstruction = 1958–1962
| numberbuilt = 72
| capacity = 670
| trainlength = {{convert|63700|mm|ft|abbr=on}}
| width = {{convert|2920|mm|ft|abbr=on}}
| height = {{convert|3720|mm|ft|abbr=on}}
| wheeldiameter = * drive wheels: {{convert|1000|mm|ft|abbr=on}}
* rolling wheels: {{convert|940|mm|ft|abbr=on}}
| maxspeed = {{convert|110|km/h|mph|abbr=on}}
| weight = {{convert|123|t|lb|abbr=on}}
| enginetype = LK-450
| poweroutput = 580 kW
| brakes = Knorr
}}

'''PKP class EW55''' (manufacturer's designation: '''Pafawag 3B/4B''') were [[Standard-gauge railway|standard-gauge]], three-car, high-platform [[Electric multiple unit|electric multiple units]] produced between 1958 and 1962 in a quantity of 72 units by the [[Bombardier Transportation Polska|Pafawag]] factory in [[Wrocław]]. Starting in 1959, they were directed to [[Katowice]] and [[Warsaw]]. In 1964, the vehicles ended service in [[Upper Silesia]], and their operation was finally concluded in 1995.

== Origins, design, and production ==
[[File:Pafawag Wrocław, montaż EZT.jpg|thumb|Assembly of EMUs at Pafawag, with two carriages of the ''3B/4B'' unit visible in the lower right corner]]
Due to the shortage of suburban units in the Warsaw railway junction and the anticipated high demand for such vehicles in the Katowice junction as well, it was decided to develop and manufacture a new electric multiple unit (EMU) in [[Poland]].<ref name=":3">{{Cite journal |last=Dobrowolski |first=Maciej |year=1996 |title=Rozwój produkcji elektrycznych zespołów trakcyjnych w Polsce |journal=Technika Transportu Szynowego |language=pl |location=Łódź |publisher=EMI-PRESS |volume=5 |pages=3–15 |issn=1232-3829}}</ref>

In 1952, the Railway Electrification Office, using the operational results of the [[PKP class EW51|EW51]] and {{Interlanguage link|PKP class EW54|lt=EW54|pl|EW54}} series units, prepared preliminary design assumptions. In the following years, the parameters and design solutions for individual devices of the new unit were refined, and in 1954, final production assumptions were created, also considering the experience from the {{Interlanguage link|PKP class EN56|lt=EN56|pl|EN56}} units. In 1956, the {{Interlanguage link|Central Design Office of the Railway Equipment Industry|pl|Instytut Pojazdów Szynowych „Tabor”}} completed the technical design of the vehicle, which was given the factory designation ''3B/4B''.<ref name=":4">{{Harvard citation text|Kroma|Sosiński|Zintel|2012|pp=226–232}}</ref> The lead designer responsible for the mechanical part was Sławomir Mossakowski, while the electrical and traction parts were developed by Maciej Dobrowolski. The construction of the unit used achievements from Western technical thought and existing documentation.<ref name=":3" /> The Pafawag factory in Wrocław was chosen as the manufacturer of the new vehicles.<ref name=":5">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=9–10}}</ref>

The ongoing electrification of Polish railways also required an increasing number of units for local traffic. Therefore, immediately after the development of the high-platform vehicle, work began on a low-platform unit.<ref name=":3" /> The ''3B/4B'' type EMU became the prototype for a new unit with the industrial designation ''[[PKP class EN57|5B/6B]]''.<ref name=":5" />

Production of the ''3B/4B'' type units began in 1958.<ref>{{Cite journal |last=Terczyński |first=Paweł |year=2005 |title=Pafawag – kronika produkcji |journal=Świat Kolei |language=pl |location=Łódź |publisher=Emi-press |volume=10 |pages=18–23 |issn=1234-5962}}</ref> In January 1959, the prototype unit was completed, and by 1962, Pafawag in Wrocław had delivered a total of 72 EMUs of this type to [[Polish State Railways]].<ref name=":6">{{Cite journal |last=Terczyński |first=Paweł |year=2001 |title=Elektryczny zespół trakcyjny serii EW55 |journal=Świat Kolei |language=pl |location=Łódź |publisher=Emi-press |volume=12 |page=41 |issn=}}</ref> The numbering of subsequent units was two-digit, as it was assumed from the beginning that their number would not exceed 100 units.<ref name=":0" />

Immediately after the production of the ''3B/4B'' type vehicles ended, serial and long-term production of the low-platform [[PKP class EN57|EN57]] units for [[Regional rail|regional]] traffic began. These were a design development of the high-platform units and were equipped with almost identical components.<ref name=":6" />

== Construction ==

=== Carbody ===
The electric multiple units (EMUs) of the EW55 series consisted of three carriages: two [[Control car|control cars]] and one  [[railcar]].<ref name=":0" /> The control cars (factory designation ''3B'') were the end cars, labeled as ''ra'' and ''rb'' (control car ''a'' and ''b'') on the Polish State Railways, while the railcar (factory designation ''4B'') was in the middle and labeled ''s''.<ref name=":0" /> The cars were connected using a so-called short "factory" [[Railway coupling|coupler]] (without a head, non-detachable in operational conditions) and a passenger passageway. On the ends of the control cars (at the beginning and end of the unit), so-called long couplers (automatic Scharfenberg couplers) were installed, allowing the units to be connected into trains. The EW55 units were designed to operate in multiple units with other units of the same series, but there was no possibility of passenger passage between connected units.<ref name=":0" />

Each car's [[underframe]] was constructed from rolled and pressed or bent steel sheets,<ref name=":7">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=32–34}}</ref> forming a series of longitudinal beams known as stringers or main girders and transverse beams known as crossbeams.<ref name=":7" /> The entire construction was welded.<ref name=":7" /> The end beams and twist beams, which were critical areas in the underframe, were designed as box constructions to ensure high strength.<ref name=":7" />

The windows in the side walls of the passenger compartments were two-part, with widths of 750 and 1,100 mm. The lower part was fixed in the window frame using rubber gaskets, while the upper part was set in an aluminum frame and could be tilted inward.<ref name=":8">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=41–43}}</ref> The front windows in the driver's cabs were fixed in frames using rubber gaskets.<ref name=":8" /> The side windows in the driver's cabs were 750 mm wide and fully retractable.<ref name=":8" /> All window panes were made of tempered glass.<ref name=":8" />

=== Interior and passenger space ===
Each of the three cars in the EW55 unit had four compartments with a central aisle between the seats, accessible to passengers and separated by three vestibules. Each vestibule had a pair of automatically sliding, pneumatically operated doors, 1,300 mm wide.<ref name=":9">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=17–19}}</ref> The end compartments of the control cars were the conductor's compartments, with 8 seats and manually operated single-leaf external doors on each side of the train.<ref name=":9" />

The seats were designed as hard benches, 900 mm long, with a seat depth of 450 mm, seat height from the floor of 440 mm, and backrest height from the floor of 985 mm; each bench weighed 40.7 kg.<ref name=":10">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=35–41}}</ref>

Electric heating radiators with a total power of 67.2 kW<ref name=":0" /> were placed under the benches in the passenger compartments, either singly or in pairs.<ref name=":10" />

Luggage racks in the passenger compartments were installed along the side walls above the windows.<ref name=":10" /> The ceiling had two parallel rows of fluorescent lighting, each with 25 W fluorescent tubes without covers.<ref name=":9" />

=== Rolling chassis ===
Each end car was supported by two [[Bogie|bogies]] with a wheelbase of 2,700 mm<ref name=":11">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=26–27}}</ref> and an axle diameter of 160 mm.<ref name=":12">{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=22–26}}</ref> The wheels of the trailing bogies were made of St65P steel, with a diameter of 940 mm, a width of 135 mm, and a thickness of 65 mm when new (30 mm when worn).<ref name=":12" />

The central railcar was supported by two driving bogies with a wheelbase of 2,700 mm<ref name=":11" /> and axle diameters of 170 mm and 175 mm.<ref name=":12" /> The wheels of the driving bogies were made of 70P steel, with a diameter of 1,000 mm, a width of 135 mm, and a thickness of 75 mm when new (35 mm when worn).<ref name=":12" />

The bogies of the EW55 series vehicles were equipped with tyred [[Wheelset (rail transport)|wheelsets]], hydraulic shock absorbers, [[Leaf spring|leaf springs]], and [[Coil spring|coil springs]].<ref name=":11" /> The pivot spacing in all cars was 14,800 mm.<ref name=":0" />

The [[rolling chassis]] of the railcar housed all the electrical and pneumatic equipment.<ref name=":9" />

=== Power supply and drive ===
Direct current at 3,000 V, supplied through an overhead line, was collected by two symmetrical [[Current collector|current collectors]] of type AKP-1 or AKP-4E,<ref>{{Harvard citation text|Domański|Kowalczyk|Skoniecki|1974|pp=118–123}}</ref> mounted on the roof of the central railcar.<ref name=":9" /> This current powered 4 traction motors located in the driving bogies of the central car.<ref name=":11" /> The torque of each traction motor was transmitted to the driving wheelset via a single-sided [[gear train]] consisting of a small and a large gear wheel.<ref name=":1" />

== Operation ==
{| class="wikitable" style="text-align:center;"
!Country
!Operator
!Number of units
!Designation
!Years of operation
!Sources
|-
|Poland
|Polish State Railways
|72
|E55-01 to 72 <small>(until 1959)</small>
EW55-01 to 72 <small>(from 1959)</small>
|1959–1995
|<ref name=":2" /><ref name=":6" /><ref>{{Harvard citation text|Kroma|Sosiński|Zintel|2012|pp=22–25}}</ref>
|}
[[File:EW55-03 (kadr), Warszawa Śródmieście, 1977.jpg|thumb|EW55-03 at the [[Warszawa Śródmieście railway station]]]]
Initially designated as the E55 series, the ''3B/4B'' type EMUs were reclassified to EW55 in mid-1959.<ref name=":4" /> These units were first assigned to the {{Interlanguage link|Warszawa Grochów depot|lt=Warszawa Grochów|pl|Warszawa Grochów}}, Warszawa Ochota, and Katowice maintenance depots.<ref name=":6" /> They ended their service in [[Upper Silesia]] in 1964, and by 1969, all units had been transferred to the Warszawa Ochota depot.<ref name=":6" /> Throughout the 1970s and 1980s, during repairs and inspections, these units were equipped with a third headlight and destination sign covers, similar to those used on the EN57 series vehicles.<ref name=":4" />

By the end of the first half of 1982, there were 68 units of the EW55 series in the inventory of the Central Directorate of District State Railways.<ref>{{Cite journal |last=Terczyński |first=Paweł |year=2009 |title=Trakcja elektryczna PKP w latach 1976–1990 |journal=Świat Kolei |language=pl |location=Łódź |publisher=Emi-Press |volume=6 |pages=36–41 |issn=1234-5962}}</ref> In October 1990, 66 EW55 units were stationed at the Warszawa Ochota depot. During the 1990s, these vehicles began to be decommissioned, and their operation officially ended in the spring of 1995. Units numbered 01, 47, and 50 were kept for museum purposes, with unit 50 being the last to be decommissioned.<ref name=":4" /> However, due to a lack of final decisions, these vehicles were eventually scrapped.<ref name=":6" /> Additionally, units numbered 33, 35, and 38 were preserved at the {{Interlanguage link|Pesa Mińsk Mazowiecki|pl|Pesa Mińsk Mazowiecki}} company and transported to the Ochota depot in July 1999. Polish State Railways initially decided to dismantle these units at the Ochota depot,<ref>{{Cite journal |last=Boduszek |first=R. |year=1999 |title=Ostatnie EW55 |journal=Świat Kolei |language=pl |location=Łódź |publisher=Emi-press |volume=4 |page=5 |issn=}}</ref> but later that same month, they were transferred to a scrap yard in [[Pruszków]]. Despite efforts by railway enthusiasts to preserve at least one of these vehicles as a historical monument, no positive decision was made, and the units were scrapped by the end of 1999.<ref name=":4" />

== References ==
{{reflist}}

== Bibliography ==

* {{Cite book |last1=Domański |first1=Emilian |title=Elektryczne zespoły trakcyjne serii EW55 i EN57 |last2=Kowalczyk |first2=Edward |last3=Skoniecki |first3=Janusz |publisher=Wydawnictwa Komunikacji i Łączności |year=1974 |edition=2 |location=Warsaw |language=pl |ref={{sfnref|Domański|Kowalczyk|Skoniecki|1974}}}}
* {{Cite book |last1=Kroma |first1=Robert |title=Normalnotorowe wagony silnikowe PKP 1945–1990 |last2=Sosiński |first2=Janusz |last3=Zintel |first3=Krzysztof |publisher=BWH Kolpress |year=2012 |isbn=978-83-933257-3-3 |edition=1 |series=Encyklopedia taboru |location=Poznań |language=pl |ref={{sfnref|Kroma|Sosiński|Zintel|2012}}}}
{{Polish State Railways rolling stock}}

[[Category:Electric multiple units of Poland]]
[[Category:Pafawag multiple units]]
[[Category:3000 V DC multiple units]]