Editing T-34 (section)

==Development and production==
===Origins===
In 1939, the most numerous [[Tanks in the Soviet Union|Soviet tank]] models were the [[T-26]] [[infantry tank]] and the [[BT tank|BT series]] of fast tanks. The T-26 was slow-moving, designed to keep pace with infantry on the ground. The BT tanks were [[cavalry tank]]s: fast-moving and light, designed for [[Maneuver warfare|manoeuver warfare]]. Both were Soviet developments of foreign designs from the early 1930s: the T-26 was based on the British [[Vickers 6-Ton]], and the BT tanks were based on a design from American engineer [[J. Walter Christie]].<ref>{{citation |last=Sale |first=Richard |url=http://turcopolier.typepad.com/the_athenaeum/2013/01/the-soviet-command-economy-by-richard-sale.html |title=America and Britain and a note on the Soviet Command Economy |date=23 January 2013 |work=The Athenaeum |page=5 |access-date=24 January 2013 |archive-date=25 May 2020 |archive-url=https://web.archive.org/web/20200525141344/http://turcopolier.typepad.com/the_athenaeum/2013/01/the-soviet-command-economy-by-richard-sale.html |url-status=live }}</ref>

[[File:T-34 prototypes.jpg|thumb|[[BT-7]], A-20, T-34 (model 1940), and T-34 (model 1941)]]

In 1937, the [[Red Army]] assigned engineer [[Mikhail Koshkin]] to lead a new team to design a replacement for the BT tanks at the [[Malyshev Factory|Kharkiv Komintern Locomotive Plant]] (KhPZ). The [[prototype]] tank, designated A-20, had a modified [[BA-20]] engine and was specified with {{cvt|20|mm|in|1}} of [[vehicle armour|armour]] and a 45&nbsp;mm (1.77&nbsp;in) gun. The production model used a [[Kharkiv model V-2|Model V-2-34]] engine designed by [[Chelpan Konstantin Fyodorovich|Konstantin Chelpan]] which ran on less-flammable diesel fuel and had a [[V12 engine|V12]] configuration. It also had an 8×6-wheel convertible drive similar to the BT tank's 8×2, which allowed it to run on wheels without [[caterpillar track]]s.<ref>{{harvnb|Zheltov|Pavlov |Pavlov| 1999|p=}}</ref>{{page needed|date=August 2022}} This feature had greatly saved on maintenance and repair of the unreliable tank tracks of the early 1930s, and allowed tanks to exceed {{convert|85|km/h}} on roads, but gave no advantage in combat and its complexity made it difficult to maintain. By 1937–38, track design had improved and the designers considered it a waste of space, weight, and maintenance resources, despite the road speed advantage.<ref>{{harvnb|Zaloga|Grandsen|1984|pp=66, 111}}</ref> The A-20 also incorporated previous research (BT-IS and BT-SW-2 projects) into [[sloped armour]]: its all-round sloped armour plates were more likely to deflect rounds than perpendicular armour.<ref>Yaziv, D.; Chocron, S.; Anderson, Jr., C.E.; Grosch, D.J. "Oblique Penetration in Ceramic Targets". ''Proceedings of the 19th International Symposium on Ballistics IBS 2001'', Interlaken, Switzerland: 1257–64</ref>

During the [[Battle of Lake Khasan]] in July 1938 and the [[Battles of Khalkhin Gol]] in 1939, an undeclared border war with [[Japan]] on the frontier with occupied [[Manchuria]], the Soviets deployed numerous tanks against the [[Imperial Japanese Army]] (IJA). Although the IJA [[Type 95 Ha-Go|Type 95 ''Ha''-''Go'']] light tanks had [[diesel engine]]s,<ref>{{harvnb|Zaloga|2007|p=}}</ref>{{page needed|date=April 2021}} the Red Army's T-26 and BT tanks used petrol engines which, while common in tank designs of the time, often burst into flames when hit by IJA tank-killer teams<ref>{{harvnb|Coox |1990|p=311}}</ref> using [[Molotov cocktail]]s. Poor-quality welds in the Soviet armour plates left small gaps between them, and flaming petrol from the Molotov cocktails easily seeped into the fighting and engine compartment; portions of the armour plating that had been assembled with [[rivet]]s also proved to be vulnerable.<ref>{{harvnb|Coox| 1990|p=309}}</ref> The Soviet tanks were also easily destroyed by the Japanese Type 95 tank's 37&nbsp;mm gunfire, despite the low velocity of that gun,<ref>{{harvnb|Coox| 1990|pp=437, 993}}</ref> or "at any other slightest provocation".<ref>{{harvnb|Zaloga|Grandsen|1984|p=111}}</ref> The use of riveted armour led to a problem whereby the impact of enemy shells, even if they failed to disable the tank or kill the crew on their own, would cause the rivets to break off and become projectiles inside the tank.

[[File:Medium tank A-32.jpg|thumbnail|Medium tank A-32]]
After these battles, Koshkin convinced Soviet leader [[Joseph Stalin]] to let him develop a second prototype, a more heavily armed and armoured "universal tank" that reflected the lessons learned and could replace both the T-26 and the BT tanks. Koshkin named the second prototype A-32, after its {{cvt|32|mm|in|1}} of frontal armour. It had an L-10 76.2&nbsp;mm (3&nbsp;in) gun, and the same Model V-2-34 diesel.<ref name="ReferenceC"/> Both were tested in [[quality control|field trials]] at [[Kubinka]] in 1939, with the heavier A-32 proving to be as mobile as the A-20. A still heavier version of the A-32, with 45&nbsp;mm (1.77&nbsp;in) of front armour, wider tracks, and a newer L-11 76.2&nbsp;mm gun, was approved for production as the T-34. Koshkin chose the name after the year 1934, when he began to formulate his ideas about the new tank, and to commemorate that year's decree expanding the armoured force and appointing [[Sergo Ordzhonikidze]] to head tank production.<ref name="ReferenceB">{{harvnb|Zaloga |1994|p=6}}</ref>

Valuable lessons from Lake Khasan and Khalkhin Gol regarding armour protection, mobility, quality welding, and main guns were incorporated into the new T-34 tank, which represented a substantial improvement over the BT and T-26 tanks in all four areas.<ref>{{harnvb|Coox| 1990|p=998}}</ref> Koshkin's team completed two prototype T-34s in January 1940. In April and May, they underwent a grueling {{convert|2000|km|adj=on}} drive from [[Kharkiv]] to [[Moscow]] for a demonstration for the [[Moscow Kremlin|Kremlin]] leaders, to the [[Mannerheim Line]] in [[Finland]], and back to Kharkiv via [[Minsk]] and [[Kiev]].<ref name="ReferenceB" /> Some [[powertrain|drivetrain]] shortcomings were identified and corrected.<ref>{{harvnb|Zaloga|Grandsen|1983|p=6}}</ref>

===Initial production<span class="anchor" id="Establishing and maintaining production"></span><span class="anchor" id="Production history"></span>===
[[File:T-34 Model 1940.jpg|thumb|left|Pre-production prototype A-34 with a complex single-piece hull front.]]

Resistance from the military command and concerns about high production cost were finally overcome by anxieties about the poor performance of Soviet tanks in the [[Winter War]] in Finland, and the effectiveness of German tanks during the [[Battle of France]]. The first production T-34s were completed in September 1940, completely replacing the production of the T-26, the BT series and the multi-turreted [[T-28 (medium tank)|T-28]] medium tank at the KhPZ plant.<ref>[[#CITEREFZaloga1994|Zaloga 1994:4]]</ref> Koshkin died of [[pneumonia]] (exacerbated by the drive from Kharkiv to Moscow) at the end of that month, and the T-34's drivetrain developer, [[Alexander Alexandrovich Morozov|Alexander Morozov]], was appointed Chief Designer.<ref name="Zaloga-1984-130">{{harvnb|Zaloga|Grandsen|1984|p=130}}</ref>

The T-34 posed new challenges for the Soviet industry. It had heavier armour than any medium tank produced to date, and there were problems with defective armour plates.<ref name="Zaloga1983p6">{{harvnb|Zaloga|Grandsen|1983|p=6}}</ref> Only company commanders' tanks could be fitted with radios (originally the 71-TK-3 radio set), due to their expense and short supply – the rest of the tank crews in each company signalled with flags.<ref name="Zaloga-1983-14" /> The L-11 gun did not live up to expectations, so the [[Vasiliy Grabin|Grabin]] Design Bureau at [[Gorky Factory No. 92|Gorky Factory N.92]] designed the superior [[76 mm tank gun M1940 F-34|76.2&nbsp;mm F-34 gun]].{{efn|see [[designations of Soviet artillery]] for explanation of naming convention}} No bureaucrat would approve production of the new gun, but Gorky and KhPZ started producing it anyway; official permission came from the [[USSR State Defense Committee|State Defense Committee]] only after troops praised the weapon's performance in combat against the Germans.<ref name="Zaloga-1984-130" />

Production of this first T-34 series – the Model 1940 – totalled only about 400,<ref name="RussianBattlefield2000">''The Russian Battlefield'' [[#Reference-Russian Battlefield-2000|2000]]</ref> before production was switched to the Model 1941, with the F-34 gun, 9-RS radio set (also installed on the [[SU-100]]), and even thicker armour.<ref>{{harvnb|Zaloga|Grandsen|1983| p=14}}, {{harvnb|Zaloga|Grandsen|1984|pp=113, 184}}, [[#Reference-Harrison-2002|Harrison (2002:181)]], [[#Reference-KMDB-2006|KMDB (2006)]].</ref>

===Mass production===
[[File:RIAN archive 1274 Tanks going to the front.jpg|thumb|left|T-34 tanks headed to the front.]]
Subassemblies for the T-34 originated at several plants: Kharkiv Diesel Factory N.75 supplied the model V-2-34 engine, Leningrad [[Kirovsky Factory]] (formerly the Putilov works) made the original L-11 gun, and the Dinamo Factory in Moscow produced electrical components. Tanks were initially built at Plant N.183, in early 1941 at the [[Stalingrad Tractor Factory]] (STZ), and starting in July at [[Krasnoye Sormovo Factory No. 112|Krasnoye Sormovo Factory N.112]] in [[Nizhny Novgorod|Gorky]].<ref name="Zaloga1983p6" />{{efn|Due to a shortage of new Model V-2-34 diesel engines and a need to produce as many T-34s as possible, the initial production run from the Gorky factory were equipped with the BT tank's [[Mikulin M-17]] petrol aircraft engine, and inferior [[transmission (mechanics)|transmission]] and [[clutch]].{{Sfn|Zheltov|Pavlov|Pavlov|2001|p=40–42}} }}

{| class="wikitable sortable floatright" style="text-align:right;"
|-
|+Total Soviet tank production<ref name=sk>{{cite book|title=Stalin's Keys to Victory: The Rebirth of the Red Army|year=2007|publisher=Stackpole Books|location=Mechanicsburg, PA|isbn=978-0-8117-3423-3|url=https://books.google.com/books?id=JE7Yd2sNBu4C&pg=PA34|first=Walter S. Jr.|last=Dunn|page=34|access-date=20 April 2021|archive-date=31 March 2023|archive-url=https://web.archive.org/web/20230331150852/https://books.google.com/books?id=JE7Yd2sNBu4C&pg=PA34|url-status=live}}</ref>
|-
! Type !! Number
|-
| Light tanks || 14,508
|-
| '''T-34''' || '''35,119'''
|-
| '''T-34-85''' || '''29,430'''
|-
| KV and KV-85 || 4,581
|-
| IS || 3,854
|-
| SU-76 || 12,671
|-
| '''SU-85''' || '''2,050'''
|-
| '''SU-100''' || '''1,675'''
|-
| '''SU-122''' || '''1,148'''
|-
| SU-152 || 4,779
|}

After [[Nazi Germany|Germany's]] surprise invasion of the Soviet Union on 22 June 1941 ([[Operation Barbarossa]]), the [[Wehrmacht]]'s rapid advances forced the evacuation and relocation of Soviet tank factories eastwards to the [[Ural Mountains]], an undertaking of immense scale and haste that presented enormous logistic difficulties and was extremely punishing to the workers involved. Alexander Morozov personally supervised the evacuation of all skilled engineers and laborers, machinery and stock from KhPZ to re-establish the factory at the site of the [[Uralvagonzavod|Dzerzhinsky Ural Railcar Factory]] in [[Nizhny Tagil]], renamed Stalin Ural Tank Factory N.183.<ref>{{harvnb|Zaloga|Grandsen|1983| p=17}}</ref> The Kirovsky Factory, evacuated just weeks before the Germans surrounded Leningrad, moved with the Kharkiv Diesel Factory to the [[Chelyabinsk Tractor Plant|Stalin Tractor Factory]] in [[Chelyabinsk]], soon to be nicknamed ''Tankograd'' ("Tank City"). The workers and machinery from Leningrad's Voroshilov Tank Factory N.174 were incorporated into the Ural Factory and the new Omsk Factory N.174. The [[Uralmash|Ordzhonikidze Ural Heavy Machine Tool Works]] (UZTM) in [[Yekaterinburg|Sverdlovsk]] absorbed workers and machines from several small machine shops in the path of German forces.

While these factories were being rapidly moved, the industrial complex surrounding the [[Volgograd Tractor Factory|Dzerzhinsky Tractor Factory]] in Stalingrad continued to work double shifts throughout the period of withdrawal (September 1941 to September 1942) to make up for production lost, and produced 40% of all T-34s during the period.<ref>{{harvnb|Zaloga | Grandsen |1983| p=13}}</ref> As the factory became surrounded by heavy fighting in the [[Battle of Stalingrad]] in 1942, the situation there grew desperate: manufacturing innovations were necessitated by material shortages, and stories persist of unpainted T-34 tanks driven out of the factory directly to the battlefields around it.<ref>{{harvnb|Zaloga |1994|p=23}}</ref> Stalingrad kept up production until September 1942.

Soviet designers were aware of design deficiencies in the tank, but most of the desired remedies would have slowed tank production and so were not implemented: the only changes allowed on the production lines through to 1944 were those to make production simpler and cheaper. New methods were developed for automated [[welding]] and [[hardening (metallurgy)|hardening]] the armour plate, including innovations by Prof. [[Evgeny Paton]].<ref>"[https://archive.today/20120905165316/http://www.paton.kiev.ua/eng/inst/person/patoneo.html Paton Evgeny Oscarovich]", at the E.O. Paton Electric Welding Institute. Retrieved 17 November 2008.</ref> The design of the 76.2&nbsp;mm [[F-34 gun Model 1941]] was reduced from an initial 861 parts to 614.<ref name="Zaloga-1984-131">{{harvnb|Zaloga|Grandsen|1984|p=131}}</ref> The initial narrow, cramped turrets, both the cast one and the one welded of rolled armour plates bent to shape, were since 1942 gradually replaced with the somewhat less cramped hexagonal one; as it was mostly cast with only a few, simple flat armour plates welded in (roof etc.), this turret was actually faster to produce. Limited [[rubber]] supplies led to the adoption of all-steel, internally sprung road wheels, and a new clutch was added to an improved five-speed transmission and engine, improving reliability.<ref name="auto2">{{harvnb|Zaloga|Grandsen|1983|p=18}}</ref>

[[File:T-34-76 RB8.JPG|thumb|left|Polish T-34 Model 1942 in [[Poznań]], Poland. The model 1942's hexagonal turret distinguishes it from earlier models.]]

Over two years, the unit production cost of the T-34 was reduced from 269,500&nbsp;[[Soviet rouble|Rbls]] in 1941, to 193,000&nbsp;Rbls, and then to 135,000&nbsp;Rbls.<ref name="Zaloga-1984-131"/>

In 1943, T-34 production had reached an average of 1,300 per month; this was the equivalent of three full-strength [[Division (military)#Armored division|tank divisions]].<ref>Zaloga 1984:225</ref> By the end of 1945, over 57,300 T-34s had been built: 34,780 T-34 tanks in multiple variants with 76.2&nbsp;mm guns in 1940–44,{{Citation needed|date=July 2013}} and another 22,609 of the revised T-34-85 model in 1944–45.<ref name="auto3">''The Russian Battlefield'' [[#Reference-Russian Battlefield-2003|2003]]</ref> The single largest producer was Factory N.183 (UTZ), building 28,952 T-34s and T-34-85s from 1941 to 1945. The second-largest was [[Krasnoye Sormovo Factory]] N.112 in Gorky, with 12,604 in the same period.<ref>{{harvnb|Michulec| Zientarzewski| 2006|p=220}}</ref>

At the start of the German-Soviet war, T-34s comprised about four percent of the Soviet tank arsenal, but by the end it made up at least 55% of tank production (based on figures from;<ref>Zaloga 1984:125–6, 225</ref> Zheltov lists even larger numbers<ref>{{harvnb|Zheltov|Pavlov|Pavlov|2001|p=}}</ref>{{page needed|date=August 2022}}

Following the end of the war, a further 2,701 T-34s were built prior to the end of Soviet production. Under licence, production was restarted in [[People's Republic of Poland|Poland]] (1951–55) and [[Czechoslovakia]] (1951–58), where 1,380 and 3,185 T-34-85s were made, respectively, by 1956.<ref>Drachkovitch, Milorad M. (ed.) ''East Central Europe: Yesterday, Today, Tomorrow.'' Hoover Press 1982:150.</ref> Altogether, as many as 84,070 T-34s are thought to have been built, plus 13,170 self-propelled guns built on T-34 chassis.<ref name="Zaloga-1996-18"/> It was the most-produced tank of the Second World War, and the second most-produced tank of all time, after its successor, the [[T-54/55]] series.<ref name="ReferenceA" />