Tatra KT4

{{More citations needed|date=September 2018}}{{Infobox tram

| name = Tatra KT4

| image = 250px

| caption = KT4SU in Lviv

| manufacturer = ČKD Tatra

| assembly =

| constructed = 1977–97

| numberbuilt = 1,747

| designer =

| predecessor =

| successor =

| art-sections = 1

| trainlength = {{convert|18100|mm|ftin|frac=8|abbr=on}}

| width = {{convert|2200|mm|ftin|frac=8|abbr=on}}

| height = {{convert|3100|mm|ftin|frac=8|abbr=on}}

| weight = {{convert|19.9|t}}

| capacity = 26–38 {{small|(Seated)}}
105–168 {{small|(Standing)}}

| maxspeed = {{convert|65|km/h|abbr=on}}

| doors = 4

| floorheight =

| poweroutput =

| traction motors = 4 x {{convert|40|kW|hp|abbr=on}}

| steep gradient =

| bogies = 2

| minimum curve =

| collectionmethod = Pantograph

| electricsystem =

| gauge = {{Track gauge|1435mm|allk=on}},
{{Track gauge|1000mm|allk=on}}

}}Tatra KT4 is the name of a four-axle type articulated tramcar developed by the Czech firm ČKD Tatra. The first pre-production vehicles entered service in Potsdam in 1975, with the first production vehicles in 1977. A total of 1,747 units were built, with initial deliveries to East Germany (DDR) and later to the USSR and SFR Yugoslavia. KT4 variants were built for both standard gauge and metre gauge tramways. Production of the KT4 tramcar was halted in 1991 due to worldwide economic and political changes at the time. Production was briefly resumed in 1997 to construct the last 20 units for Belgrade, Serbia.

File:Tatra KT4D Cabview in Oradea (Autumn Edition).webm

Since the start of the 1990s, many of the earliest production tramcars have gone through extensive refurbishment and rebuilding, including the replacement of folding doors and the installation of low-floor center sections.

The design of the tram, being without a bogie over the joint necessitates a scissor joint connecting both bogies such that the center of mass does not shift catastrophically, especially when turning.{{Cite web|title=ST4有轨电车新型铰接转向运动机构的设计_爱学术|url=https://www.ixueshu.com/document/c7cff2213dbc94b23ac06c323feed40c318947a18e7f9386.html|access-date=2021-04-21|website=www.ixueshu.com}}

History

Source: The Development of The Modern Tram, by Brian Patton

The KT4 was originally designed to demands set out by the needs of the GDR, who found bogie cars too expensive and needed a solution to their aging fleet of two-axle vehicles. The first steps into the KT4s design were made when ČKD Tatra modified a six-axle K2 tramcar, to a four-axle suspended articulation formation which later presented itself in the KT4. The KT4 has identical pedal control systems and bogies to the Tatra T3 bogie tramcar. As production continued, the design was improved, noted particularly in 1983 with the addition of thyristor control type TV3. The type is called KT4t.

Variations

Variations of the KT4 exist, though they are generally subtle and focused around seat layout and pantograph type.

KT4D – German model
KT4Dt – German model with TV3 thyristor
KT4SU – Soviet Union model
KT4YU – Yugoslav model

Note that there is no such thing as a KT4K. KT4 used in North Korea were not built by Tatra, instead built by the Shenyeng Passenger Vehicle Factory and named differently.

= KT4D =

The KT4D model was delivered to the following GDR cities:

City	Delivery years	Number delivered
class="wikitable"
Berlin	1976–88	574
Brandenburg	1979–83	16
Cottbus	1978–90	65
Erfurt	1976–90	156
Frankfurt (Oder)	1987–90	34
Gera	1978–90	60
Görlitz	1987–90	11
Gotha	1981–82	6
Leipzig	1976	8
Potsdam	1974–87	45
Plauen	1976–88	45
Zwickau	1987–88	22
TOTAL	1974–90	1,042

In 1984, Leipzig handed over their eight trams to Berlin. Since the early 2000s, the Tatra tramcars in the former GDR are being replaced and sold to other countries in Central and Eastern Europe.{{in lang|uk}} [https://www.epravda.com.ua/publications/2020/09/7/664779/ Course on protectionism: can localization save Ukrainian producers], Ukrayinska Pravda (7 September 2020)

== Original KT4D ==

File:KT4D 001 (Prototyp).jpg|KT4D prototype in Potsdam

File:Berlin, Tatra KT4.jpg|KT4D in Berlin

File:Brandenburg an der Havel, Tatra KT4D (1).jpg|KT4D in Brandenburg/Havel

File:Stadtbahn Erfurt Tw 471.jpg|KT4D in Erfurt

File:Frankfurt (Oder), Tatra KT4.jpg|KT4D in Frankfurt (Oder)

File:Straßenbahn Gera DDR Tatra Tram 320 and Trabant. Aug 1989.jpg|KT4D in Gera

File:Gotha, Tatra KT4 (1).jpg|KT4D in Gotha

File:Görlitz Tatra no. 6 July 1992.jpg|KT4D in Görlitz

File:Plauen, Tatra KT4 (1).jpg|KT4D in Plauen

File:Potsdam, Tatra KT4 (3).jpg|KT4D in Potsdam

File:Clp 20100921 SRS Tw 22 Vogelsdorfer Straße.jpg|at SRS Tramways

File:Zwickau, Tatra KT4.jpg|KT4D in Zwickau

== Modernised KT4D ==

File:Clp 20080826 Tw 6159+6172 Blockdammweg.jpg|KT4Dm in Berlin

File:205 Gleisdreieck.JPG|KT4Dm in Frankfurt/Oder

File:139Polnocna wokolica.JPG|KTNF6 (KT4D rebuilt with a central low-floor segment) in Cottbus

File:StraBaGera04.JPG|KTNF8 (another variant with central low-floor segment added) coupled with KT4Dm in Gera

File:Uk gth-tw301 03 g.jpg|KT4D mod 301 in Gotha 2005

File:302+318Demiani.JPG|Both actual colors of KT4D in Görlitz

File:208-Tunnel-08.10.07.jpg|Modernised KT4D in Plauen

File:Potsdam Kt4Dm 156+256 am Platz der Einheit 2007.JPG|KT4Dm double in Potsdam

File:SVZ Zwickau 942+937.jpg|KT4DC in Zwickau

== Sold KT4Ds ==

File:Tram in Liepaja.JPG|Former Gera KT4D 239 in Liepāja, Latvia

File:GalatiTramway20060716.jpg|Former Berlin KT4D 82 in Galaţi, Romania

File:Tatra KT4DtM, Szczecin, Poland.jpg|Former Berlin KT4Dm in Szczecin, Poland

File:Tatra KT4D tram in Tallinn, 2006.jpg|Former Cottbus KT4D in Tallinn, Estonia

File:20191225_Tratra_Tram_Weimar.jpg|Former Erfurt KT4D in Weimar, Germany

Image:TramKaliningrad4.JPG|KT4SU in Kaliningrad

File:KTNF6 Nr. 28 Schöneiche 2014.jpg|KTNF6 in Schöneiche

File:Low-middle tram in Tallinn.JPG|KT6T (KTNF6) in Tallinn

= KT4SU =

The Soviet Union ordered the KT4SU for their meter-gauge tramways, the following cities received deliveries:

City	Delivery years	Number delivered
class="wikitable"
Yevpatoria	1987–90	18
Kaliningrad	1987–90	30
Liepāja	1983–88	22
Lviv	1976–88	145
Pyatigorsk	1988–90	25
Zhytomyr	1981–88	20
Tallinn	1980–90	74
Vinnytsia	1980–90	81
TOTAL	1976–90	415

= KT4YU =

The KT4YU is the Yugoslav variant of the tramcar, which were delivered to the Serbian and Croatian capitals. The last KT4s ever produced were delivered to Belgrade in 1997. Those tramcars were equipped with IGBT modules and recuperative braking and named KT4M-YUB (where B stands for Belgrade to be distinguished from Zagreb model). In 2002, 30 Belgrade tramcars were modernized in Goša FOM / Inekon, and marked as KT4-YUBM.

City	Delivery years	Number delivered
class="wikitable"
Belgrade	1980–97	220
Zagreb	1985–86	51
TOTAL	1980–97	271

File:Tatra_ČKD_Belgrade.jpg|Tatra KT4M-YU (1997) in Belgrade

File:Tree_Tatras_Belgrade.jpg|Tatras KT4 in Belgrade

File:Tatra_KT4_YUB(elgrade).jpg|KT4-YUB in Belgrade

File:BeogradTram.jpg|KT4YUBM in Belgrade

File:Tatra_KT4M-YUB_.jpg|Tatra KT4M-YU (1997) in Belgrade

File:Tatra_KT4_Belgrad.jpg|Tatra KT4-YU in Belgrade

File:Tatra_Belgrad_Night.jpg|Tatra KT4-YU in Belgrade

File:ČKD-KT4 Beograd_Tašmajdan_poslednja_serija_KT4_(1997).jpg|Tatra KT4M-YU (1997) in Belgrade

File:ČKD-KT4_Beograd_Tašmajdan.jpg|KT4YUBM in Belgrade

File:ČKD_Tatra_Belgrad_Banjica.jpg|KT4YU in Belgrade

File:Tatra KT4 Zagreb.jpg|Tatra KT4YU in Zagreb

File:Zagreb_tram_(24).jpg|Tatra KT4YU in Zagreb

File:KT4_Zagreb.jpg|Tatra KT4YU in Zagreb

File:Tranvía_13,_Zagreb,_Croacia,_2014-04-20,_DD_01.JPG|Tatra KT4YU in Zagreb

File:TatraKT4YU333.jpg|Tatra KT4YU in Zagreb

File:Tram_Zagreb_line_9.jpg|Tatra KT4YU in Zagreb

= Shenyang ST4 =

A series of KT4 trams were also produced for Pyongyang, North Korea by the Shenyeng Passenger Vehicle Factory in China named ST4,{{Cite web|last=|first=|date=April 1997|title=对研制ST4型有轨电车的体会|url=http://www.cqvip.com/qk/89602x/199704/4001058234.html|archive-url=|archive-date=|access-date=|website=}} but have subsequently had their articulation removed due to structural defects of the joint.{{Cite web|title=Shenfeng KT4 — Roster|url=https://transphoto.org/list.php?mid=6024|access-date=2021-01-14|website=transphoto.org}} During their service, they were based at Songsin depot. These trams were fully withdrawn in 1999 and the bodies rebuilt into Chollima 971 articulated trolleybuses or Chollima 961 trolleybuses. Since then, some Chollima 971 trolleybuses were converted into Chollima 961 trolleybuses by removing the rear section.{{Cite web|title=Chollima 971|url=https://transphoto.org/model/5310/|access-date=2021-01-14|website=transphoto.org}} 150 trams were ordered, though only 51 vehicles are known to have been recorded.{{Cite web|title=Shenyang ST4 — Roster|url=https://transphoto.org/list.php?mid=6024|access-date=2021-05-31|website=transphoto.org|language=en}}

These vehicle's main difference was its 2.5 meter wide body, four 45 kW traction motors, a maximum speed of 60 km/h, a seating capacity of 56 and standing capacity of 125. Its weight was also higher, at a net weight of 22.5 tons.