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modified: Nov 10, 2012
T-34-85 was a further development of the Soviet T-34 medium tank. It was initiated in response to the increasing ineffectiveness of the T-34 against new German armor. The battle of Kursk showed that the new Panther and Tiger tanks were superior in both firepower and armor.

Development History
Four gun design teams were given the task of up-arming the T-34. Grabin was developing an 85mm S-53 gun at the Central Artillery Design Bureau (TsAKB). F. Petrov was developing the 85mm D-5 gun at Artillery Plant No. 9 in Sverdlovsk. A prototype was completed in June 1943. A. Savin took over Grabin's old bureau at Zavod Nr. 92 (ZiS). And K. Siderenko began design work on the 85mm S-18 gun.

The D-5 and S-53 underwent state trials in July 1943 with the D-5 winning. However, the D-5 was too large to fit in a T-34 turret so it was initially mounted in the new IS heavy tank and the SU-85 tank destroyer.

Grabin convinced the GAU that his gun can be mounted in a standard T-34 Model 1943 turret. A small number of conversions were made and firing trials were conducted at the Gorokhovets proving ground in mid-summer. The tests showed that the S-53 was too large for the T-34 turret.

The guns (it's unclear if it's two or four of them) were trialled at the Gorokhovets proving ground. Due to his political influence, Grabin's S-53 was selected to arm the T-34 despite the fact that the D-5 was entering production for the SU-85.

Aleksandr Morozov's T-34 Main Design Bureau (GKB-T-34) in Nizhni Tagil suggested that the project be shifted to the Krasnoye Sormovo Plant No. 112 to further accelerate the program.

Obiekt 135 was undertaken by V. Krylov's design team. The new turret design was assigned to V. Kerichev. Experimental mountings of an 85mm gun in the T-43 (T-43-85) showed that the turret was not suitable without modifications. The commander was moved from the center rear of the turret to behind the gunner in order to provide space for the longer recoil of the 85mm gun.

The drawings of the production version of the S-53 completed in the autumn of 1943 revealed that the gun was bulky and would lack proper depression and elevation in the new turret.

Two unarmed Obiekt 135 prototypes with the new turret were completed in November 1943. After trials at Kubinka proving ground, Obiekt 135 was approved by the State Defense Committee (GKO) for Army service on December 15, 1943 as the T-34-85, despite incomplete trials.

Stalin ordered tank industry officials to have the T-34-85 ready for production by February 1944. Further acceptance trials of the S-53 revealed issues with the recoil system. In order to meet Stalin's deadline, the GAU ordered Zavod Nr. 112 Krasnoye Sormovo plant to adapt the 85mm D-5S to the T-34-85. This interim version, sometimes called T-34-85 Model 1943 was produced in February-March 1944 armed with the tank version of the D-5S, the D-5T.

In January, GAU examined Grabin's S-50 and S-53, Petrov's D-5 and the LB-1 (also referred to as the LB-85 to distinguish it from the later 100mm LB-1) from a GULAG prison design team. None of the guns were satisfactory and it was decided that the final gun should include the better features of each gun.

Savin modified Grabin's S-53 gun to fit in the new turret while incorporating other improvements. Firing trials of the redesigned gun were conducted in January 1944. It was designated the ZiS-S-53 in recognition of Savin's contributions and production began in March 1944. The ZiS-S-53 replaced the D-5T on the new T-34-85 Model 1944 in March 1944. A total of about 800 T-34-85s were built with the interim D-5T gun.

The T-34-85 Model 1944 had a modified turret developed by a team under M.A. Nabutovskiy at the main design bureau in Nizhni Tagil. The TSh-15 telescope was replaced with the new TSh-16 articulated telescopic sight leading to a redesign of the turret interior. The gunner and commander's stations were moved further towards the rear of the turret. The gunner's periscopic roof sight was replaced by an MK-4 periscope.

In addition, the radio was moved from the right hull front adjacent to the hull machine gunner up into the turret near the commander. The shape of the gun mantlet changed because of the method in which the inner mantlet was attached to the new gun, and because of the repositioning of the new telescopic sight.

Different casting techniques at two foundries in Nizhni Tagil and Irkutsk resulted differences in the appearance of the T-34-85 turrets. The most widespread type, believed to be produced at the Novo Tagil foundry in Nizhni Tagil, had flattened sides. The other foundry produced a type from composite castings which was distinguished by a sharp joint at the rear floor.

The T-34-85 was produced at three plants during the Great Patriotic War: Uralvagonzavod No. 183 in Nizhni Tagil, Krasnoye Sormovo No. 112 in Gorkiy, and the Omsk Tank Plant No. 174. Uralvagonzavod accounted for 78.2% of T-34-85 production.

In 1942, T-34s constituted 51% of Soviet tank production which rose to 79% by 1943/44. Although the T-34-85 accounted for most of the T-34 production in 1944, some factories still built the T-34 Model 1943 with the 76mm gun.

The Red Army started to receive the T-34-85 in March 1944. The first units that obtained the tank included the 2nd, 6th, 10th, and 11th Guards Tank Corps. The T-34-85s made their combat debut in late March 1944 during operations in western Ukraine.

The Germans initially misidentified the T-34-85 as the T-43, a project that was abandoned earlier.

Allied countries
The T-34-85 was supplied to nations allied with the Soviet Union in the last year of the Great Patriotic War. The largest Allied user of the T-34-85 was the Polish People's Army (LWP). The LWP received an early production T-34-85 in May 1944 for training. The first significant number of service tanks were received in October 1944.

The 1st, 2nd, 3rd, 4th, and 16th armored brigades of Poland were equipped at least in part with the T-34-85. The Polish tanks' first combat action was during the January 1945 Vistula-Oder offensive. They were also involved in the final stages of the Prague operation in May 1945. The LWP received a total of 328 T-34-85 tanks during the war, of which 132 survived the fighting. Plans to deploy an LWP SU-100 tank destroyer regiment were delayed until the summer of 1945.

The 1st Czechoslovak Tank Brigade was deployed on the Eastern Front. In the spring of 1945, this unit received 52 T-34-85 tanks before the Prague operation, while serving with the 4th Ukrainian Front. The number of tanks had risen to about 60 T-34-85s by the end of the war.

The Soviet Union formed the 2nd Tank Brigade, which together with Britain's 1st Tank Brigade, was intended to support Tito's Yugoslav National Liberation Army. The Soviet brigade was equipped with T-34-85s and it reached Yugoslavia in late 1944.

The Germans captured a small number of T-34-85s during the summer of 1944 which were used on an ad hoc basis. Finland also captured seven T-34-85 tanks that summer which were used against the Red Army until capitulation, and against the Germans afterwards.

Production Improvements
Several changes were introduced in 1944. An electric power traverse was added inside the turret. The additional space required by the electric drive resulted a rectangular bulge on the left turret side of tanks produced since the summer of 1944.

A new enlarged commander's cupola with a one-piece hatch instead of a two-piece one, was introduced in late 1944 or early 1945. In the late spring of 1944, a front mudguard with a sharply angled shape was introduced. The TDP (tankovoy dymoviy pribor) smoke concealment system was added to the rear of tanks in late 1944.

One of the wheel producers began providing a new cast, spoked wheel which was used alongside the more common drawn concave wheel in use since 1941. Tire suppliers shifted from perforated to solid rubber wheels in 1945.

A total of 11,050 T-34-85 tanks were produced in 1944 while 18,330 were built in 1945.

The Kharkov Tractor Plant No. 75, which was the location of the T-34 design bureau, was rebuilt in 1944 after the end of occupation by the Germans. The plant started producing T-34-85 tanks in late 1945 making it the fourth factory to do so.

Around 1945, a new turret variant was introduced which split the turret ventilators, placing one forward of the loader's hatch, and leaving one at the right rear corner. These turrets were mainly used by the Kharkov plant. The standard type of turret casting with twin mushroom vents was still being produced.

T-34-85 production continued after the end of the Great Patriotic War. T-44 production began in 1945. However, the production of T-44s was limited due to mechanical teething problems. Therefore, the T-34-85 was manufactured in large numbers until the advent of the T-54A. The last few hundred T-34-85 tanks were assembled in 1950 at Gorkiy from remaining subcomponents.

Including foreign post-war production, a total of 35,120 T-34-76 and 48,950 T-34-85 tanks were built. In addition, 13,170 assault gun variants were manufactured resulting a grand total of 97,240 vehicles. Therefore, the T-34-85 was the most produced tank of the Great Patriotic War era.

The T-34-100 was a variant of the T-34-85 developed at the Morozov design team. The project was started when it was felt that a more powerful gun was desirable after encounters with German Panthers in 1944. The T-34-100 mounted a 100mm D-10S gun as used on the SU-100. The hull gunner position was eliminated to provide more space for ammunition. The turret diameter had to be increased from 1.6 to 1.7m to accommodate the gun, and a new, slightly larger turret was designed as well. A few prototypes were tested. However, the gun was too large for the T-34-85 chassis and there was more interest in the new T-44 and T-44-100, so the project was terminated.

As in the T-34-76, there were two crewmen in the hull of the T-34-85: the driver/mechanic, and the machine gunner. During 1944, there were severe shortages of trained tank crews. Women who worked in the Urals tank plants were enlisted as tank drivers to make up for the shortages.

Many tank units had only four crewmen or sometimes three, before the organization was changed to accommodate the fifth crewman. The hull machine gun position was usually the first position left vacant in the event of crew shortages.

In the turret, the gunner and tank commander sit on the left side of the turret. The loader is located on the right. The main gun was mounted slightly asymmetrically to the right to provide additional space for the tank fire controls. The gunner sat on a seat attached to the frame of the gun assembly. The commander was provided with a fold-down seat attached to the turret ring. The loader had a small saddle attached by snap-ties to allow the seat to be folded out of the way during combat.

The tank gun was of conventional design with recoil recuperators above the gun, a fast-action drop breech, and a barrel length of 54.6 calibers. There were at least three standard rounds for the gun. The standard anti-tank round was the BR-365. Later in 1944, the improved high velocity BR-365P appeared. The most common round was the O-365 HE-FRAG projectile.

55 rounds of tank gun ammunition were carried. Later versions had 60 rounds. A rack in the turret bustle contained 16 rounds. Four more rounds were located on the right rear turret side near the gunner. Most of the ammunition was found in the floor in six metal ammunition bins each containing six rounds. Five additional rounds were stowed in cavities on the right side of the hull. The floor was generally covered with a rubberized mat to protect the ammunition bins. A trained crew can usually achieve a rate of fire of three to four rounds per minute.

The gunner was equipped with a TSh-16 telescopic sight, articulated with the gun. The gunner had two sets of gun and turret controls, the turret elevation gear at his right hand and the turret traverse at his left. The first production batches of T-34-85 through the summer of 1944 used a simple manual turret traverse system. The MB-20V electric drive was introduced later in 1944 relieving the gunner of this responsibility during the gun-laying process, and also increasing the turret traverse speed. The electric traverse system was used to move the turret into the right position with fine adjustments being implemented manually.

The gunner was provided with the PTK-5 sight in the original T-34-85 Model 1943 with the D-5T gun. In later versions, it was replaced with the MK-4 periscopic sight. Unlike the PTK-5, the MK-4 was not used for aiming but general observation.

The commander sits behind the gunner. The commander's all-around vision cupola had armored glass vision slits as well as an MK-4 periscopic sight. The roof of the cupola traversed, allowing the commander to use the MK-4 periscopic sight in all directions.

The T-34-85 was usually equipped with the 9-R transmitter-receiver. The internal fuel capacity of the tank was reduced from 610 to 545 liters, but external fuel capacity was increased from 180 to 270 liters by the use of three cylindrical fuel tanks.

The TDP smoke system, which was introduced in late 1944, consisted of two MDSh smoke canisters fitted to the rear plate of the tank. The canisters were electrically detonated to camouflage a tank unit when it encountered enemy anti-tank guns. The MDSh canister mountings were sometimes used for small fuel canisters instead.

The T-34-85 introduced improved Multi-cyclone air filters. Later production T-34-85s used the V-2-34M diesel engine.

Foreign Production
License production rights for the T-34-85 were sold to Poland. T-34-85 production at the Bumar Plant in Labedy lasted from 1951 to 1955, when it was replaced with the T-54A. Polish versions can usually be distinguished from Soviet ones by their smoother turret castings. Polish T-34-85s were exported to some of the other Warsaw Pact countries including East Germany.

Czechoslovakia began T-34-85 production at the same time as Poland and lasted until 1958 when T-54A production began. A new factory was erected at Martin for final assembly. Czechoslovak T-34-85s resembled the Polish versions. However, they can be distinguished by the housing for an infantry signal button on the rear corner of the left hull side, and by the use of the post-war pattern tow-cable assembly on the left hull side. The Stalin Plant in Martin also began license production of the related SU-100 at the same time. Czechoslovakia exported the T-34-85 and SU-100 to the Middle East in the early 1950s.

Yugoslavia decided to incorporate a variety of changes before starting production. The resulting tank was called the Teski Tenk Vozilo A (Heavy Tank Type A) and featured a locally designed turret and a modified hull with the front corners of the superstructure angled. Seven prototypes were built in 1949-50 before relations between Stalin and Tito soured and Soviet support for the project was withdrawn.

Post-war Improvements
The Soviet Union had two major modernization programs for the T-34-85. The first one started in 1960. The V-2-34 engine was replaced by the improved V-34-M11 with the new VTI-3 air-cleaners and small changes to the cooling and lubrication system. A GT-4563A or G-731 generator was introduced to keep the batteries charged. The new BDSh canisters replaced the MDSh canisters in the TDP tank smoke system. A BVN infrared driving sight was installed and an FG-100 infrared headlight was added next to the normal white light headlight for night driving. The 9-R radio was replaced by the improved 10-RT-26E. The modernization was also extended to related vehicles such as the SU-100. Similar programs were undertaken in Poland, Czechoslovakia and other Warsaw Pact countries. The upgraded Polish tanks were called T-34-85M1.

The second modernization effort was instituted in 1969. The 10-RT radio was replaced by the latest R-123. The infrared night driving equipment was replaced with newer periscopes and headlights. Small automotive upgrades were also made. To make obtaining fuel from external tanks easier, a fuel pump and its associated stowage box were added to the left hull side. The two BDSh smoke canister racks were usually removed or moved to the left hull side between the fuel pump box and the external fuel cell. In their place, a new pair of stowage racks which can carry a 200-liter fuel drum and an unditching beam were added.

In the 1970s, a new replacement wheel was developed for the T-34-85 and T-44 that resembled the T-55 starfish wheel, but had a narrower track. The new wheel was used for the T-34-85 Model 1969 only when stocks of the older wheels were exhausted at local rebuilding plants.

Some of these changes were also made by other Warsaw Pact countries. The Polish modernized version was designated the T-34-85M2. It included additions on the outside of the vehicle for stowage, a water-proofing kit to allow deep-wading, associated snorkel equipment, and other features. Some countries also made their own local modifications. For example, Bulgaria introduced a local loader's hatch fitted with a traversable external anti-aircraft machine gun.

Multiple technical support vehicles were based on the T-34-85 chassis. In addition, there were also civilian variants built for heavy construction, logging, and other purposes.

References: OW, STCV, TMT, TMW