T-34-85

The T-34 is a Soviet medium tank introduced in 1940. When introduced its 76.2 mm (3 in) tank gun was less powerful than its contemporaries while its 60-degree sloped armour provided good protection against anti-tank weapons. The Christie suspension was inherited from the design of American J. Walter Christie's M1928 tank, versions of which were sold turret-less to the Red Army and documented as "farm tractors", after being rejected by the U.S. Army. The T-34 had a profound effect on the conflict on the Eastern Front in the Second World War, and had a short lasting impact on tank design. After the Germans encountered the tank in 1941 during Operation Barbarossa, German general Paul Ludwig Ewald von Kleist called it "the finest tank in the world" and Heinz Guderian affirmed the T-34's "vast superiority" over German tanks. Alfred Jodl, chief of operations staff of the German armed forces noted in his war diary "the surprise at this new and thus unknown ''wunder''-armament being unleashed against the German assault divisions," although its armour and armament were surpassed later in the war.

The T-34 was the mainstay of the Soviet Red Army armoured forces throughout the war. Its general specifications remained nearly unchanged until early 1944, when it received a firepower upgrade with the introduction of the greatly improved T-34-85 variant. Its production method was continuously refined and rationalized to meet the needs of the Eastern Front, making the T-34 quicker and cheaper to produce. The Soviets ultimately built over 80,000 T-34s of all variants, allowing steadily greater numbers to be fielded despite the loss of tens of thousands in combat against the German Wehrmacht. Replacing many light and medium tanks in Red Army service, it was the most-produced tank of the war, as well as the second most-produced tank of all time (after its successor, the T-54/T-55 series). Harrison 2002 With 44,900 lost during the war, it also suffered the most tank losses ever. Its development led directly to the T-44, then the T-54 and T-55 series of tanks, which in turn evolved into the later T-62, that form the armoured core of many modern armies. T-34 variants were widely exported after World War II, and as recently as 2010 more than 130 were still in service.

Development and production

Origins

In 1939, the most numerous Soviet tank models were the T-26 infantry tank and the 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 tanks: fast-moving and light, designed for 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.

In 1937, the Red Army had assigned engineer Mikhail Koshkin to lead a new team to design a replacement for the BT tanks at the Kharkiv Komintern Locomotive Plant (KhPZ). The prototype tank, designated A-20, had a modified BA-20 engine and was specified with of armour, a 45 mm (1.77 in) gun, the production model used a Model V-2-34 engine, a less-flammable diesel fuel in a V12 configuration designed by Konstantin Chelpan. 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 tracks. This feature had greatly saved on maintenance and repair of the unreliable tank tracks of the early 1930s, and allowed tanks to exceed 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. 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.

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'' light tanks had diesel engines, 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 using Molotov cocktails. 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 rivets also proved to be vulnerable. The Soviet tanks were also easily destroyed by the Japanese Type 95 tank's 37 mm gunfire, despite the low velocity of that gun, or "at any other slightest provocation". 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.

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 of frontal armour. It had an L-10 76.2 mm (3 in) gun, and the same Model V-2-34 diesel. Both were tested in 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 mm (1.77 in) of front armour, wider tracks, and a newer L-11 76.2 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.

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. Koshkin's team completed two prototype T-34s in January 1940. In April and May, they underwent a grueling drive from Kharkiv for a demonstration for the Kremlin leaders, to the Mannerheim Line in Finland, and back to Kharkiv via Minsk and Kiev. Some drivetrain shortcomings were identified and corrected.

Initial production

Political pressure came from conservative elements in the army to redirect resources into building the older T-26 and BT tanks, or to cancel T-34 production pending completion of the more advanced T-34M design. This pressure was brought to bear by the developer of the KV-1 tank which was in competition with the T-34.

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 at the KhPZ plant. 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 Morozov, was appointed Chief Designer.

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. 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. The L-11 gun did not live up to expectations, so the Grabin Design Bureau at Gorky Factory N.92 designed the superior 76.2 mm F-34 gun. No bureaucrat would approve production of the new gun, but Gorky and KhPZ started producing it anyway; official permission came from the State Defense Committee only after troops praised the weapon's performance in combat against the Germans.

Production of this first T-34 series – the Model 1940 – totalled only about 400,''The Russian Battlefield'' 2000 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.

Mass production

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 KhPZ N.183, in early 1941 at the Stalingrad Tractor Factory (STZ), and starting in July at Krasnoye Sormovo Factory N.112 in Gorky.

After 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 Dzerzhinsky Ural Railcar Factory in Nizhny Tagil, renamed Stalin Ural Tank Factory N.183. The Kirovsky Factory, evacuated just weeks before the Germans surrounded Leningrad, moved with the Kharkiv Diesel Factory to the 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 Ordzhonikidze Ural Heavy Machine Tool Works (UZTM) in 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 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. 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. 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 the armour plate, including innovations by Prof. Evgeny Paton. The design of the 76.2 mm F-34 gun Model 1941 was reduced from an initial 861 parts to 614. 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.

Over two years, the unit production cost of the T-34 was reduced from 269,500  Rbls in 1941, to 193,000 Rbls, and then to 135,000 Rbls.

In 1943, T-34 production had reached an average of 1,300 per month; this was the equivalent of three full-strength tank divisions. By the end of 1945, over 57,300 T-34s had been built: 34,780 T-34 tanks in multiple variants with 76.2 mm guns in 1940–44, and another 22,609 of the revised T-34-85 model in 1944–45.''The Russian Battlefield'' 2003 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.

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; Zheltov lists even larger numbers

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 Poland (1951–55) and Czechoslovakia (1951–58), where 1,380 and 3,185 T-34-85s were made, respectively, by 1956. 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. 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.

Design

Overview

The T-34 had well-sloped armour, a relatively powerful engine and wide tracks. The initial T-34 version had a powerful 76.2 mm gun, and is often called the T-34/76 (originally a World War II German designation, never used by the Red Army). In 1944, a second major version began production, the T-34-85, with a larger 85 mm gun intended to deal with newer German tanks.

Comparisons can be drawn between the T-34 and the U.S. M4 Sherman tank. Both tanks were the backbone of the armoured units in their respective armies, both nations distributed these tanks to their allies, who also used them as the mainstay of their own armoured formations, and both were upgraded extensively and fitted with more powerful guns. Both were designed for mobility and ease of manufacture and maintenance, sacrificing some performance for these goals. Both chassis were used as the foundation for a variety of support vehicles, such as armour recovery vehicles, tank destroyers, and self-propelled artillery. Both were an approximately even match for the standard German medium tank, the Panzer IV, though each of these three tanks had particular advantages and weaknesses compared with the other two. Neither the T-34 nor the M4 was a match for Germany's heavier tanks, the Panther (technically a medium tank) or the Tiger I; the Soviets used the IS-2 heavy tank and the U.S. used the M26 Pershing as the heavy tanks of their forces instead.

Dimensions, road speed and engine horsepower of the various models did not vary significantly, except for the T-43, which was slower than the T-34.

Armour

The heavily sloped armour design made the tank better protected than the armour thickness alone would indicate. The shape also saved weight by reducing the thickness required to achieve equal protection. A few tanks also had appliqué armour of varying thickness welded onto the hull and turret. Tanks thus modified were called ''s ekranami'' (russian: с экранами, "with screens").

The USSR donated two combat-used Model 1941 T-34s to the United States for testing purposes in late 1942. The examinations, performed at the Aberdeen Proving Ground, revealed problems with overall armour build quality, especially of the plate joins and welds, as well as the use of soft steel combined with shallow surface tempering. Leak issues were noted: "In a heavy rain lots of water flows through chinks/cracks, which leads to the disabling of the electrical equipment and even the ammunition". Earlier models of the T-34, until the Model 1942, had cast turrets whose armour was softer than that of the other parts of the tank, and offered poor resistance even to 37 mm anti-aircraft shells. Early T-34s also suffered from poor quality welds, leading to instances of shells which would not have penetrated the tank under normal circumstances to penetrate anyway. They also suffered from rushed manufacturing, leading to inconsistent protection.

In addition, close examination of the T-34 at the Aberdeen Testing Ground showed that a variety of alloys were used in different portions of the armour on the T-34. " Mn- Si- Mo steels were employed for the thinner rolled armour sections, Cr-Mo steels for the thicker rolled armour sections, Mn-Si- Ni-Cr-Mo steels were employed for both rolled and cast steel components from 2" to 5" in thickness, and Ni-Cr-Mo steels were employed for some of the moderately thick cast armour sections". The armour was heat-treated in order to prevent penetration by armour-piercing shells, but this also caused it to be structurally weak, as the armor was very hard and thus brittle, resulting in strikes by high explosive shells causing spalling.

Despite these deficiencies, the T-34's armour proved problematic for the Germans in the initial stages of the war on the Eastern Front. In one wartime account, a single T-34 came under heavy fire upon encountering one of the most common German anti-tank guns at that stage of the war: "Remarkably enough, one determined 37 mm gun crew reported firing 23 times against a single T-34 tank, only managing to jam the tank’s turret ring." Similarly, a German report of May 1942 noted the ineffectiveness of their 50 mm gun as well, noting that "Combating the T-34 with the 5 cm KwK tank gun is possible only at short ranges from the flank or rear, where it is important to achieve a hit as perpendicular to the surface as possible." However, a Military Commissariat Report of the 10th Tank Division, dated 2 August 1941 reported that within 300–400 m the 37 mm Pak 36's armour-piercing shot could defeat the frontal armour. According to an examination of damaged T-34 tanks in several repair workshops in August to September 1942, collected by the People's Commissariat for Tank Industry in January 1943, 54.3% of all T-34 losses were caused by the German long-barreled 5 cm KwK 39 gun.

As the war went on, the T-34 gradually lost some of its initial advantages. The Germans responded to the T-34 by fielding large numbers of improved anti-tank weapons such as the towed 7.5 cm Pak 40 anti-tank gun, while hits from 88 mm-armed Tigers, anti-aircraft guns and 8.8 cm Pak 43 anti-tank guns usually proved lethal. In 1942 the German Panzer IVs were refitted with the 7.5 cm KwK 40 due to the inadequate anti tank performance of previous German tank designs against the T-34. The upgunned Panzer IV posed a serious threat to the T-34-76, being able to penetrate the frontal turret of a T-34-76 at a range of at any angle.

A ''Wa Pruef 1'' report estimated that, with the target angled 30° sideward, a Panther tank could penetrate the turret of a T-34-85 from the front at ranges up to 2000 m, the mantlet at 1200 m, and the frontal hull armour at 300 m.Jentz 1995:128 According to the ''Pantherfibel'' (the Panther tank manual for its crew), the T-34's glacis could be penetrated from 800 m and the mantlet from 1500 m at 30° sideward angle.

A Waffenamt-Prüfwesen 1 report estimated that with the T-34 angled 30 degrees sidewards and APCBC round, the Tiger I's 8.8 cm KwK 36 L/56 would have to close in to to achieve a penetration in the T-34's glacis, and could penetrate the frontal turret of a T-34-85 at 1,400 m, the mantlet at 400 m, and the nose at 300 m Ground trials by employees of NIBT Polygon in May 1943 reported that the 88 mm KwK 36 gun could pierce the T-34 frontal hull from 1,500 meters at 90 degrees and cause a disastrous burst effect inside the tank. The examined hull showed cracks, spalling, and delamination due to the poor quality of the armour. It was recommended to increase and improve the quality of welds and armour.

Analysis of destroyed T-34 tanks in the Korean War found that the 76 and 90 mm armour-piercing rounds of the M41 Walker Bulldog and M46 Patton could penetrate the T-34 at most angles from . The maximum range at which the tanks could penetrate the T-34 could not determined due to a lack of data at higher combat ranges.

In late 1950 a T-34-85 tank was captured by the UN security force in the Korean War. An evaluation of the tank was conducted by the USA which found that the sloped armour of the T-34 was desirable for deflecting shells. They also concluded that the armour was deemed as satisfactory as armour strength was comparable to US armour of similar hardness and that the quality of the material used was "high-grade". Similarly, casting was seen as high quality although casting defects were found in the side armour of the tank that negatively affected armour strength. The abundance of gaps in the joints of the armour was seen as an undesirable feature of the tank due to the risk of injury from "entry of bullet splash and shell fragments".

Firepower

The F-34 gun, fitted on the vast majority of T-34s produced through to the beginning of 1944, was able to penetrate any early German tank's armour at normal combat ranges. When firing APCR shells, it could pierce at and of armour at The best German tanks of 1941, the Panzer III and Panzer IV, had no more than of flat frontal armour. However by 1942 the Germans had increased the hull armour on the Panzer IV to which provided good protection at normal combat distances. The F-34 also fired an adequate high explosive round.

The gun sights and range finding for the F-34 main gun (either the TMFD-7 or the PT4-7) were rather crude, especially compared to those of their German adversaries, affecting accuracy and the ability to engage at long ranges. As a result of the T-34's two-man turret, weak optics and poor vision devices, the Germans noted:

The Germans also noted that the T-34 was very slow to find and engage targets, while their own tanks could typically get off three rounds for every one fired by the T-34. As the war progressed the Germans created heavier tank designs like the Tiger I or Panther which were both immune to the 76mm gun of the T-34 when fired upon from the front. This meant that they could only be penetrated from the sides at ranges of a few hundred metres. Due to low anti-tank performance, the T-34 was upgraded to the T-34-85 model. This model, with its 85 mm (3.35 in) ZiS gun, provided greatly increased firepower compared to the previous T-34's 76.2mm gun. The 85 mm gun could penetrate the turret front of a Tiger I tank from and the driver's front plate from at the side angle of 30 degrees, and the larger turret enabled the addition of another crew member, allowing the roles of commander and gunner to be separated and increasing the rate of fire and overall effectiveness. The D-5T was capable of penetrating the Tiger I's upper hull armour at 1,000 metres. When firing on the frontal armour of the Panther at an angle of 30 degrees sidewards, the T-34-85 could not penetrate its turret at . This meant that the T-34 would have to resort to using tungsten rounds or firing on the weaker sides of the Panther to destroy it.

The greater length of the 85 mm gun barrel – – made it necessary for crews to be careful not to plough it into the ground on bumpy roads or in combat. Tank commander A.K. Rodkin commented: "the tank could have dug the ground with it in the smallest ditch illing the barrel with dirt If you fired it after that, the barrel would open up at the end like the petals of a flower", destroying the barrel. Standard practice when moving the T-34-85 cross-country in non-combat situations was to fully elevate the gun, or reverse the turret.

During the Korean War, the USA captured a T-34-85. US engineering analysis and testing concluded that the T-34-85 could penetrate at , performing similarly to the HVAP rounds of the M41. The Americans also concluded the maximum range of the gun was , but the effective range was only up to .

Mobility

The T-34 was powered by a Model V-2-34 38.8 L V12 Diesel engine of 500 hp (370 kW), giving a top speed of 53 km/h (33 mph). It used the coil-spring Christie suspension of the earlier BT-series tanks, using a "slack track" tread system with a rear-mounted drive sprocket and no system of return rollers for the upper run of track, but dispensed with the heavy and ineffective convertible drive.

The Red Army's T-34s also experienced considerable problems due to the mud:
In 1944 February 4, the 21st Guards Tank Brigade with 32 T-34, was ordered to proceed by road to Tolstoye Rogi, a journey of approximately 80 kilometers.
The T-34 had a good reputation for its ability to negotiate difficult ground conditions, but the relatively short journey was a real challenge. Of the 32 tanks, no less than 19 got stuck in the mud or suffered mechanical breakdowns.

Ergonomics

The original 76mm armed T-34 suffered from the unsatisfactory ergonomic layout of its crew compartment compared to the later 85mm variant. The two-man turret crew arrangement required the commander to aim and fire the gun, an arrangement common to most Soviet tanks of the day. The two-man turret was "cramped and inefficient" and was inferior to the three-man (commander, gunner, and loader) turret crews of German Panzer III and Panzer IV tanks. The Germans noted the T-34 was very slow to find and engage targets while the Panzers could typically get off three rounds for every one fired by the T-34.

Early in the war, the commander fought at a further disadvantage; the forward-opening hatch and the lack of a turret cupola forced him to observe the battlefield through a single vision slit and traversable periscope. German commanders liked to fight "heads-up", with their seat raised and having a full field of view – in the T-34 this was impossible. Soviet veterans condemned the turret hatches of the early models. Nicknamed ''pirozhok'' ("stuffed bun") because of its characteristic shape, it was heavy and hard to open. The complaints of the crews urged the design group led by Alexander Morozov to switch in August 1942 to using two hatches in the turret.

The loader also had a difficult job due to the lack of a turret basket (a rotating floor that moves as the turret turns); the same fault was present on all German tanks prior to the Panzer IV. The floor under the T-34's turret was made up of ammunition stored in small metal boxes, covered by a rubber mat. There were nine ready rounds of ammunition stowed in racks on the sides of the fighting compartment. Once these rounds had been used, the crew had to pull additional ammunition out of the floor boxes, leaving the floor littered with open bins and matting and reducing their performance.

Most of the problems created by the cramped T-34/76 turret, known before the war, were corrected with the provision of a bigger cast three-man turret on the T-34-85 in 1944.

General reliability

The T-34's wide track and good suspension gave it excellent cross-country performance. Early in the tank's life, however, this advantage was greatly reduced by the numerous teething troubles the design displayed: a long road trip could be a lethal exercise for a T-34 tank at the start of the war. When in June 1941, the 8th Mechanised Corps under Dmitry Ryabyshev marched 500 km towards Dubno, the corps lost half of its vehicles. A.V. Bodnar, who was in combat in 1941–42, recalled:

The T-34 gearbox had four forward and one reverse gear, replaced by a five-speed box on the last of the 1943 model of the T-34. The earlier transmissions were troublesome, and some tanks went into battle with a spare transmission cabled onto the engine compartment deck.

The tracks of early models were the most frequently repaired part. A.V. Maryevski later remembered:

The USSR donated two combat-used Model 1941 T-34s to the United States for testing purposes in late 1942. The examinations, performed at the Aberdeen Proving Ground, highlighted these early faults, which were in turn acknowledged in a 1942 Soviet report on the results of the testing:

Testing at Aberdeen also revealed that engines could grind to a halt from dust and sand ingestion, as the original "Pomon" air filter was almost totally ineffective and had an insufficient air-inflow capacity, starving the combustion chambers of oxygen, lowering compression, and thereby restricting the engine from operating at full capacity. The air filter issue was later remedied by the addition of "Cyclone" filters on the Model 1943, and even more efficient "Multi-Cyclone" filters on the T-34-85.

The testing at Aberdeen revealed other problems as well. The turret drive also suffered from poor reliability. The use of poorly machined, low quality steel side friction clutches and the T-34's outdated and poorly manufactured transmission meant frequent mechanical failure occurred and that they "create an inhuman harshness for the driver". A lack of properly installed and shielded radios – if they existed at all – restricted their operational range to under .

Soviet tests on newly built T-34’s showed that in April 1943 only 10.1% could complete a 330 km trial and in June ’43 this went down to 7.7%. The percentage stayed below 50% till October 1943 when it rose to 78%, in the next month it dropped to 57% and in the period December ’43 – January ’44 the average was 82%.During February 1944 tests, 79% of tanks reached 300 kilometers, and of the test batches 33% reached 1,000 kilometers. This became immediately apparent to the tank troops. The deputy commander of the 1st Guards Tank Army, P. G. Dyner, commented that tanks in 1943 would reach only 75 percent of their guaranteed life span in engine hours and mileage, but in 1944 they reached 150 percent.

In 1944 June, a report written by the 2. Panzerjäger-Abteilung Company 128 (23. PzDiv.) described experiences acquired during operations with its ''Beutepanzer'' SU-85 and T-34:

On January 29, 1945, the State Defense Committee approved a decree that extended the service life guarantee of the T-34's V-2-34 engine from 200 hours to 250 hours. A report by the 2nd Guards Tank Army in February 1945 revealed that the average engine service life of a T-34 was lower than the official warranty at 185–190 hours. For comparison, the US M4 Sherman had an average engine service life of 195–205 hours.

During the Korean war the Americans captured a North Korean T-34-85, evaluating its performance. According to the tank’s instruments, it had travelled for , but the level of wear on the engine was minimal. The quality of materials used were "ample for the job" with some being "better than those used in American tanks". Protective coatings used to prevent wear of components were deemed "most effective". However the tank also had various defects. The gearbox was seen as problematic and unreliable and the US opinion of the transmission was exceptionally low, stating that the example had "by American standards already failed" attributing it to "inadequate design" as "excellent steel" was used throughout the transmission.

Operational history

Operation Barbarossa (1941)

Germany launched Operation Barbarossa, its invasion of the Soviet Union, on 22 June 1941. At the start of hostilities, the Red Army had 967 T-34 tanks and 508 KV tanks concentrated in five of their twenty-nine mechanized corps. The existence of the T-34 and KV heavy tanks proved a psychological shock to German soldiers, who had expected to face an inferior enemy. The T-34 was superior to any tank the Germans then had in service. The diary of Alfred Jodl seems to express surprise at the appearance of the T-34 in Riga.

Initially, the Wehrmacht had great difficulty destroying T-34s in combat, as standard German anti-tank weaponry proved ineffective against its heavy, sloped armour. In one of the first known encounters, a T-34 crushed a 3.7 cm PaK 36, destroyed two Panzer IIs, and left a long swathe of destruction in its wake before a howitzer destroyed it at close range. In another incident, a single Soviet T-34 was hit more than 30 times by a battalion-sized contingent of German 37mm and 50mm anti-tank guns, yet survived intact and drove back to its own lines a few hours later. The inability to penetrate the T-34's armour led to the Germans' standard anti-tank gun, the 37 mm PaK 36, being dubbed the ''Panzeranklopfgerät'' ("tank door knocker") because the PaK 36 crew simply revealed their presence and wasted their shells without damaging the T-34's armour. Anti-tank gunners began aiming at tank tracks, or vulnerable margins on the turret ring and gun mantlet, rather than the bow and turret armour. The Germans were forced to deploy 105 mm field guns and 88 mm anti-aircraft guns in a direct fire role to stop them.

Despite this, the Soviet corps equipped with these new tanks lost most of them within weeks. The combat statistics for 1941 show that the Soviets lost an average of over seven tanks for every German tank lost. The Soviets lost a total of 20,500 tanks in 1941 (approximately 2,300 of them T-34s, as well as over 900 heavy tanks, mostly KVs). Krivosheev & Erickson 1997:252, table 95. The destruction of the Soviet tank force was accomplished not only by the glaring disparity in the tactical and operational skills of the opponents, but also by mechanical defects that afflicted Soviet armour. Besides the poor state of older tanks, the new T-34s and KVs suffered from initial mechanical and design problems, particularly with regard to clutches and transmissions. Mechanical breakdowns accounted for at least 50 percent of the tank losses in the summer fighting, and recovery or repair equipment was not to be found. The shortage of repair equipment and recovery vehicles led the early T-34 crews to enter combat carrying a spare transmission on the engine deck.

Other key factors diminishing the initial impact of T-34s on the battlefield were the poor state of leadership, tank tactics, initial lack of radios in tanks, and crew training; these factors were partially consequences of Stalin's purge of the Soviet officer corps in 1937, reducing the army's efficiency and morale. This was aggravated as the campaign progressed by the loss of many of the properly trained personnel during the Red Army's disastrous defeats early in the invasion. Typical crews went into combat with only basic military training plus 72 hours of classroom instruction; according to historian Steven Zaloga:

Further action (1942–1943)

As the invasion progressed, German infantry began receiving increasing numbers of the 7.5 cm Pak 40 anti-tank guns, which were capable of penetrating the T-34's armour at long range. Larger numbers of the 88 mm ''Flak'' guns also arrived, which could easily defeat a T-34 at very long ranges, though their size and general unwieldiness meant that they were often difficult to move into position in the rough Soviet terrain.

At the same time, the Soviets incrementally upgraded the T-34. The Model 1942 featured increased armour on the turret and many simplified components. The Model 1943 (confusingly also introduced in 1942) had yet more armour, as well as increased fuel capacity and more ammunition storage. Also added were an improved engine air filter and a new clutch mated to an improved and more reliable five-speed transmission. Finally, the Model 1943 also had a new, slightly roomier (but still two-man) turret of a distinctive hexagonal shape that was easier to manufacture, derived from the abandoned T-34M project.

The T-34 was essential in resisting the German summer offensive in 1942, and executing the double encirclement manoeuvre that cut off the German Sixth Army at Stalingrad in December 1942. The Sixth Army was surrounded, and eventually surrendered in February 1943, a campaign widely regarded as the turning point of the war on the Eastern Front.

In 1943, the Soviets formed Polish and Czechoslovak armies-in-exile, and these started to receive the T-34 Model 1943 with a hexagonal turret. Like the Soviet forces themselves, the Polish and Czechoslovak tank crews were sent into action quickly with little training, and suffered high casualties.

In July 1943, the Germans launched Operation Citadel, in the region around Kursk, their last major offensive on the Eastern Front in the Second World War. It was the debut of the German Panther tank, although the numbers employed at the resulting Battle of Kursk were small and the brunt of the burden was carried by the Panzer III, StuG III, and Panzer IV. The campaign featured the largest tank battles in history. The high-water mark of the battle was the massive armour engagement at Prokhorovka, which began on 12 July, though the vast majority of armour losses on both sides were caused by artillery and mines, rather than tanks. Over 6,000 fully tracked armoured vehicles, 4,000 combat aircraft, and 2 million men are believed to have participated in these battles.

The Soviet high command's decision to focus on one cost-effective design, cutting costs and simplifying production wherever possible while only allowing relatively minor improvements, had proven to be an astute choice for the first two years of the war. However, the battles in the summer of 1943 demonstrated that the 76.2 mm gun of the T-34 was no longer as effective as it was in 1941. Soviet tank crews struggled at longer ranges with the additional frontal armour applied to the later variants of the Panzer III and Panzer IV, and were unable to penetrate the frontal armour of the new German Panther or Tiger I tank at standard combat ranges without tungsten rounds, and had to rely on tactical skill through flanking manoeuvres and combined arms.

T-34-85

After improved German Panzer IVs with the high-velocity 7.5cm (2.95 in) KwK 40 gun were encountered in combat in 1942, a project to design an entirely new Soviet tank was begun, with the goals of increasing armour protection while adding modern features like a torsion-bar suspension and a three-man turret. The new tank, the T-43, was intended to be a universal model to replace both the T-34 and the KV-1 heavy tank. However, the T-43 prototype's armour, though heavier, was not capable against German 88 mm guns, while its mobility was found to be inferior to the T-34. Finally, although the T-43 shared over 70% of its components with the T-34, manufacturing it would still have required a significant slow-down in production. Consequently, the T-43 was cancelled.

Not only were the weapons of German tanks improving, so was their armour. Soviet firing tests against a captured Tiger I heavy tank in April 1943 showed that the T-34's 76 mm gun could not penetrate the front of the Tiger I at all, and the side only at very close range. A Soviet 85 mm anti-aircraft gun, the M1939 (52-K), was found capable of doing the job, and so derivatives of it were developed for tanks. One of the resulting guns used on the original T-34 85 model (the D-5T) was capable of penetrating the Tiger I's upper hull armour at 1,000 metres. It was still not enough to match the Tiger, which could destroy the T-34 from a distance of , but it was a noticeable improvement.

With the T-43 canceled, the Soviet command made the decision to retool the factories to produce an improved version of the T-34. Its turret ring was enlarged from 1,425 mm (56 in) to 1,600 mm (63 in), allowing a larger turret to be fitted supporting the larger 85 mm gun. The prototype T-43's turret design was hurriedly adopted by Vyacheslav Kerichev at the Krasnoye Sormovo Factory to fit the T-34. This was a larger three-man turret, with radio (previously in the hull) and observation cupola in the roof. Now the tank commander needed only to command (aided by cupola and radio systems), leaving the operation of the gun to the gunner and the loader. The turret was bigger and less sloped than the original T-34 turret, making it a bigger target (due to the three-man crew and bigger gun), but with thicker 90 mm armour, making it more resistant to enemy fire. The shells were 50% heavier (9 kg) and were much better in the anti-armour role, and reasonable in a general purpose role, though only 55–60 could be carried, instead of 90–100 of the earlier shells. The resulting new tank, the T-34-85, was seen as a compromise between advocates for the T-43 and others who wanted to continue to build as many 76 mm-armed T-34s as possible without interruption.

Production of the T-34-85 began in January 1944 at Factory No. 112, first using the D-5T 85 mm gun. Parallel to the production of the T-34-85 with the D-5T gun, production of the T-34-85 using the S-53 gun (later to be modified and redesignated as the ZIS-S-53 gun) began in February 1944 at Factory No. 112. The improved T-34-85 became the standard Soviet medium tank, with an uninterrupted production run until the end of the war. A T-34-85 initially cost about 30 percent more to produce than a Model 1943, at 164,000  Rbls; by 1945 this had been reduced to 142,000 Rbls – Harrison 2002:181 during the course of World War II the cost of a T-34 tank had almost halved, from 270,000 Rbls in 1941, while its top speed remained about the same, and its main gun's armour penetration and turret frontal armour thickness both nearly doubled.

The T-34-85 gave the Red Army a tank with better armour and mobility than the German Panzer IV tank and StuG III assault gun. While it could not match the armour or weapons of the heavier Panther and Tiger tanks, its improved firepower made it much more effective than earlier models, and overall it was more cost-effective than the heaviest German tanks. In comparison with the T-34-85 program, the Germans instead chose an upgrade path based on the introduction of completely new, expensive, heavier, and more complex tanks, greatly slowing the growth of their tank production and helping the Soviets to maintain a substantial numerical superiority in tanks. By May 1944, T-34-85 production had reached 1,200 tanks per month. In the entire war, production figures for all Panther types reached no more than 6,557, and for all Tiger types (including the Tiger I and Tiger II) 2,027. Production figures for the T-34-85 alone reached 22,559.

On 12 January 1945, a column of Tiger IIs and other tanks from 424th Heavy Panzer Battalion were involved in a short-range engagement with T-34-85 tanks near the village of Lisow. Forty T-34-85 tanks commanded by Colonel N. Zhukov were attacked by the 424th Heavy Panzer battalion, which had been reinforced by 13 Panthers. The Germans permanently lost five Tiger IIs, seven Tiger Is and five Panthers for the loss of four T-34-85 tanks burnt out.

German use of T-34s

The German army often employed as much captured materiel as possible and T-34s were not an exception. Large numbers of T-34s were captured in fighting on the Eastern Front though few were T-34-85s. These were designated by the Germans as ''Panzerkampfwagen T-34 747(r)''. From late 1941, captured T-34s were transported to a German workshop for repairs and modification to German requirements. In 1943 a local tank factory in Kharkiv

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