design and layout of t-34 tanks

18 The Armor Journal Issue 03, Summer 2015

Designand layout of t-34 tanks

Aleksey Makarov and Igor Zheltov, research fellows, T-34 History Museum.

Translated by Alex Zaretser

of the Plant no.183 June 1942 production

The Armor Journal Issue 03, Summer 2015 19

The T-34 tank produced by the Plant No.183 in June 1942 was a further development of the medium tank manufactured in 1941 in Kharkov before the plant was evacuated to Nizhny Tagil. The tank was devel-

oped by the Design Bureau “520” (KB-520) of the Plant No.183 under the leadership of Chief Designer Alexander Morozov and Head of KB-520 Nikolai Kucherenko. The tank was dif-ferent from the previous versions; one of the differences was that it had a more spacious cast turret (also known as “hexagonal”). In addition, in order to reduce the complexity of the manufacturing process, a significant number of other changes were made to the tank’s design. For the same rea-son, production of majority of the parts was changed from casting to stamping.

This tank with a crew of four had a classical scheme/layout, which became widespread in the postwar world of tank manufacturing. The hull of the tank was divided into four sections. The driver’s compartment was located at the bow of the hull and had the workstation for a driver on the left side and the machine gunner/radio operator on the right side. The volume of the driver’s compartment was 2.2 m³. The tank commander, who also served as a gunner, was seated in the fighting compartment. He was located to the left of the gun, while the loader was to the right. The engine compartment, with a volume of 3.7 m³, was directly behind the fighting compartment and was separated from it by a removable bulkhead. The transmission compartment was located in the rear of the tank, and its volume was 1.5 m³.

The driver’s compartment had the following items: seats for a driver and the machine gunner who also served as the radio operator, mechanical control drives, instrumentations (KIP), DT machine gun in a ball mount, part of the ammu-nition storage, drives for the transmission compartment air exhaust louvers, two cylinders with compressed air, and part of the “ZIP” kit*.

A driver’s hatch was locat-ed in the front glacis plate. The opening was intended for enter-ing and exiting the tank by a driv-er/mechanic and gunner/radio operator; as well as to monitor the terrain by a driver in the ab-sence of enemy fire. In a combat situation the opening was closed by an armored hatch on hinges and was locked by two locking mechanisms called “zadraiki”**. A self-locking spring lock was located in the lower part of the lid between “zadraiki” and was welded to the inner side of the lid. To help with its opening, the driver’s hatch was equipped with a spring-balancing mechanism. In the open position the hatch cover could be fixed by a lock/stopper in one of six positions.

This could be done by rotating a knob and entering a tooth of the stopper into one of the recesses located on the rod of the counterweight mechanism.

The driver’s hatch cover also had two openings for the periscopic observation devices used by the driver. Each periscope was a prism made of silicate or organic glass. In the event of damage, and to protect the eyes of the driver from fragments of the prism, a protective glass was installed for both periscopes. To protect the prisms from bullets and shrapnel they could be closed on the outside with armored covers. Each armored cover could be opened or closed by a hand lever and fixed in one of the three open positions. If damaged, the prism could be replaced by one of four spares that were stored in holders inside of a box in the fighting compartment. To expand the exterior field of view, the vi-sion devices were placed at an angle to the longitudinal axis of the hatch with a turn toward the hull sides. The horizontal field of view of the right periscope was 95°; the left was 85°, and the vertical field of the view was 27°. The “blind” zone in front of the tank was 5.7 meters.

The driver’s compartment also had an additional (emer-gency) hatch. It was located by the feet of the machine-gun-ner/radio operator in the bottom of the tank.

The tank’s driving controls included left and right steering levers, pedals of the main clutch, parking (“moun-tain”) brake, and fuel supply (gas pedal/accelerator); the controls also included the gear shift lever. The pedals of the main clutch, “mountain brake” and fuel supply were locat-ed from left to right as in a conventional car. The number of instruments was minimized to simplify their control by the driver-mechanic.

The fighting compartment contained the workstations of the tank commander and loader, and included the main and auxiliary tank weapons. Two fuel tanks were installed

View of the workstation of the driver-mechanic of the T-34 tank mid-1942 production.


behind the removable steel walls (bulkheads) on the right and left sides of the hull. The majority of the 76-mm ammu-nition was located on the floor of the hull in special steel boxes called “suitcases”. Additional racks were on the side walls of the hull interior. The use of “suitcases” increased the amount of stored ammunition and located it in the place least vulnerable to enemy fire. Entering and exiting the ve-hicle by the commander and loader was done through two round hinged hatches in the roof of the turret.

In a combat situation the tank commander could conduct all round observation by using a panoramic periscope device PTK, which was in-stalled in a fixed position in the roof of the turret. The top part of the sight towered above the roof while the eyepiece was located inside the turret, at the eye level of the seated tank commander. A special all-around view mechanism allowed the prism head to rotate 360° around the vertical axis while the housing and commander’s eyepiece remained fixed. The optical system of the de-vice had a 2.5x magnification, a 26° wide field of view, and a vertical viewing range of -15° to + 30°. This optical instrument had better reliability and allowed for a greater range of target detection in comparison with similar observation devices without magnification, such as those used in the commander’s cupolas of the German Panzer III and IV medium tanks, which used simple “vision slots” with a five-layer glass. To improve visibility to the sides of a turret, two additional vision de-vices were installed. The device on the left was for the commander of the tank while the device on

the right was for the loader. Each device provided 90° hor-izontal field of observation, and ±6° vertical. The housing of each device had been welded to the inner wall of the turret in such a way so its viewing slot was directly against the cutout in the turret wall. The slot could be closed with an armored shutter; but during observation the shutter was lowered. During the battle, the observer’s eye was pro-tected by a double layered safety glass. The “blind” zone in front of the side vision slots was 17 meters.

The 76.2-mm tank gun F-34; the shell catcher is not installed. (RGVA)

Commander’s panoramic periscope PTK.

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In addition to his regular duties the commander of a T-34 served as the gunner. While this double tasking re-duced the response time to individual fire missions (there was no need to communicate with a separate gunner), the combined functions complicated the job of managing the tank during battle, especially when a tank commander was also the unit commander.

The loader, in addition to performing his main duty, could also operate the coaxial DT machine gun. In this sce-nario, the gun’s fixing lock had to be released. The design of the machine gun mounting allowed it to be fired in the range of ±5° in the vertical plane, and ±4.5° in the horizontal.

The armored volume of the engine compartment was 3.7 m³. It housed the V-2 diesel engine with air cleaner, cooling system radiators, lubrication system oil tanks, and the batteries. The transmission compartment contained the main clutch with centrifugal fan, transmission, steer-ing clutches, electric starter, final drives and two more fuel tanks. The armored volume of the transmission compart-ment was 1.5 m³.

The modernized 76.2-mm tank gun F-34 mod.1940 was the main armament of the tank. The upgrade/modern-ization of the gun was only in the installation of a barrel with “free” inner tube. It replaced the monobloc barrel and breech assembly, where the inner tube was coupled to the breech. The gun had a vertical sliding breech system with a semi-automatic follower type. The weight of the swinging assembly (barrel, breach, recoil mechanism and elevating shield at trunnions) of the gun was 1,155 kg. The 41.5 cali-bers long barrel was rifled with a constant twist. The rifled portion of the barrel was 2,562 mm in length and had 32

grooves. The fire rate of the F-34 cannon with both turret hatches closed was 5-6 rounds per minute.

The gun used fixed ammunition de-signed for the M1902/30 and M1939 divi-sional guns with the following rounds:

1. The high-explosive long-range fragmentation grenade (steel OF-350 or semi-steel OF-350A) with the KTM-1 fuse;

2. The high-explosive grenade of an old Russian type F-354 with fuses KT-3, KTM-3 or ZGT;

3. The armor-piercing tracer rounds BR-350A, BR-350B, and BR-350SP with the fuse MD-5;

4. The bullet shrapnel round Sh-354 with a 22-sec-ond time fuse or the T-6 fuse;

5. The rod shrapnel round Sh-361 with the fuse T3-UG. The 6.5 kg armor-piercing projectiles had an initial ve-

locity of 662 m/s and could penetrate a vertical 65-mm ar-mor plate (frontal armor of German tanks in service at the time) at a distance of 1000 m.

For anti-personnel fire, a coaxial 7.62-mm DT machine gun was mounted beside the main gun in the mantlet. Both of these weapons had common sight devices and aiming mechanisms. The maximum elevation angle of the gun was 28°, with the maximum depression of the angle being -5°. Fir-ing of the main gun or coaxial machine gun could be done by either hand or foot operated mechanisms. To protect the elevation mechanism from dynamic stresses during travel in a non-combat environment, a travel lock was used. The travel lock was attached to the right trunnion bracket. To fix the gun in the travel position it had to be leveled horizontal-ly, and the pin of the locking mechanism inserted into the socket located in a lower part of the trunnion bracket of the cradle/elevation shield.

Sighting the main and coaxial machine guns was done by a tank commander through a telescopic sight TMFD-7, firmly fixed to the left side of the cannon. While the telescop-ic sight ensured high precision aiming, working with it at

more than 8° elevation was not very convenient since the eyepiece moved as one with the gun.

Aiming the main and coaxial machine guns in the horizontal plane was car-ried out using the turret tra-verse mechanism (MPB)***, located to the left of the gun. Design of the MPB al-lowed the turret to be tra-versed manually or via an electric motor. The traverse speed in the manual mode would depend on how fast the MPB’s flywheel was ro-

Telescopic gun sight TMFD-7. (RGVA)

7.62mm DT machine gun. (RGVA)


Above: The balancing mechanism of a driver’s hatch; a knob of a stopper is also visible. The hand lever for the transmission compart-ment louvers is right behind the cylinder of the balancing mechanism. (A.Aksenov)

Below left: Turret traverse mechanism. (A.Aksenov)

Below right: The T-shaped handle of the main gun travel lock is visible to the right from the co-axial DT machine gun. (A.Aksenov)


tated. The electric traverse motor had 3 rotational speeds, which corresponded to the following values: the first lev-el was 2.1RPM; the second level was 3.6RPM, and the third level was 4.2RPM. The electric drive was controlled by the knob of a rheostat. To rotate the turret to the right, the knob was turned to the right; conversely to rotate it to the left the knob was turned to the left. Each direction had three posi-tions for each of the three traverse speeds but in the neutral position (required for manual traverse) the knob was locked with a button.

The second 7.62-mm DT machine gun was installed in a ball mount in the upper front plate (glacis) of the hull. The mount allowed the machine gun to be fired in the horizontal plane up to 12° to either side; and between -6° and 16° in the vertical. The area that could not be covered by MG fire in front of the tank reached 6.8 meters.

Ammunition for the 76-mm main gun consisted of 77 ar-mor-piercing and high-explosive rounds, 68 of which were in the six large (nine rounds each) and two small (seven rounds each) metal boxes (“suitcases”) located on the floor of the fighting compartment. The rest of the shells were placed in the ammunition racks on the right (three rounds) and left (six rounds) walls of the hull. Before being shipped from the fac-tory, the tank was equipped with thirty 63-round pan maga-zines for DT machine guns. The tank was also equipped with

25 F-1 hand grenades and one 7.62-mm PPSh submachine gun with four spare drum magazines.

The armor of the tank was of various thicknesses. The armored hull was a rigid welded box made of cast and rolled armor with a thickness of 20 and 45 mm. The shape of the hull, which had large angles of inclination of the armor plates, provided rational use of its volume and high armor protection. The hull consisted of the following main parts: the bow (front), sides, rear (stern), bottom, roof and lateral walls (i.e. bulkheads).

The front part of a hull consisted of an upper (part #34.29.904) and lower (part #34.29.905) rolled armor plates with a thickness of 45 mm; both plates were made of homo-geneous armor steel of the high hardness grade 8S (MZ-2), and were connected by a cast beam (part #34.29.906) made of the same armor steel as the front plates. Positioned with high angles of inclination and having a thickness ratio vs the diameter of a standard enemy artillery round close to “1”, this armor possessed higher resistance to artillery fire than the other types of armor steel.

The lower edge of the upper front armor plate (glacis plate) was welded to a crossbeam, where the beam (part #34.29.906) served as the link between lower and upper front plates. The upper edge of the glacis plate was weld-ed to the front under-turret plate (part #34.29.1705). An oval

Sketch of the T-34 hull Plant No.183 production with numbers of the armored parts as of July 1, 1942. (RGAE)


hole was cut into the right side of the glacis plate, and a cast armored dome for the ball mount of the DT machine gun was welded to the edges of that opening. The driver’s hatch was located to the left; it was protected with a cast armor hinged lid. Unfortunately, the presence of the hatch and ball mount in the glacis reduced its resistance to projectiles. The lower part of the glacis plate had two openings for access to the track tensioning mechanisms. They were closed with two armored threaded plugs. Near them (but closer to the longitudinal axis of the glacis) were two tow hooks with latches welded on. Two more tow hooks, similar by design, were also welded to the lower plate at the rear of the hull.

The upper edge of the lower front hull plate was weld-ed to the beam. Plate side edges were welded to the side plates of the hull, while the lower edge was connected to the bottom of the hull.

The left and right sides of the hull consisted of a lower (part #34.29.006) and upper (part #34.29.013) armor plates. The lower plate was positioned vertically, while the upper one was at a 40° angle. The plates were connected (weld-ed) via a horizontal armor plate (made out of two parts: #34.29.1636 and #34.29.1637). Such positioning of the side plates made the cross section of the hull shape look like a mushroom. This shape increased resistance of the upper

Above: Rear and front vews of the T-34 hull of the Plant No.183 approved for mass production July 1st, 1942. (RGAE)

Right: Brackets for the rubber bump-stops (dampers) limiting ver-tical movement of the suspension arms. The lower photo shows a double damper used for the suspension arm of the first (leading) wheel station. (V.Shaikin)


plate, the most vulnerable part of the hull, to enemy rounds; it did not interfere with track movement and did not increase the width of the tank.

The vertical side plate had four openings for brackets of the 2nd through 5th road wheels suspension arms, a cir-cular opening for the first wheel suspension arm bracket and four curved openings for the trunnions of the suspen-sion arms. A crank arm of the leading wheel (idler) and six brackets were welded on the exterior side of the vertical plate; the brackets were to accommodate rubber bump-stops (dampers) used to limit vertical movement of the sus-pension arms. Four more mounting brackets were welded on the outside of the plate as these brackets were for the

planks preventing horizontal movement of the arms. Four housings for suspension springs and a bracket for the front sus-pension assembly were welded to the inner side of the plate. The final drive housing was connected to the plate’s rear by welding and rivets.

The rear part of the hull consisted of two armor plates: the upper rear plate (part #34.29.008) and lower rear plate (part #34.29.007); and two final drive housings (parts #34.29.021 and #34.29.022). All these parts were made of homogeneous armor steel of a high hardness grade 8S (MZ-2) with a thickness of 45 mm. The top armor plate could be flipped open on three hinges; in the closed position it was bolted to the flanges, which were welded to the side and the

lower rear hull plates. The middle part of the top rear plate had a circular opening for access to the transmission com-partment. This opening was closed by an armored cover attached to the plate by a hinge and seven bolts. On both sides of the hatch there were two more holes for the exhaust pipes to go through; these holes were protected by 20 mm thick armored covers (part #34.29.023), bolted to the outside of the upper plate.

The bottom of the hull was a major binding element and consisted of four parts connected by a butt weld-ed joint; the welding between the parts was reinforced by plates with T-shaped cross-section. The bottom plates were made from 20 mm thick homogeneous armor steel of

Sketch of the roof of the T-34 hull Plant No.183 production with numbers of the armored parts as of July 1, 1942. (RGAE)

The guide plate used to retain 2nd through 5th suspension arms laterally. The guide plate was engaged by a forked extension on the suspension arm. (I.Perepelitsa)


the 2-P (MZ-3) grade. An oval opening, which served as an emergency exit for the crew, was located in the front bot-tom plate (part #34.29.1700) at the feet of a machine gun-ner/radio operator. The exit was closed from the inside with an armored hatch (part #34.29.026), which was con-nected to the bottom plate with a hinge. The hatch was fastened to the bottom by two locks (“zadrayki”**) which were held tight to the hatch flange by screw-nuts. For quick locking of the hatch a spring latch was installed on the lid.

The rear area of the bot-tom hull had a hatch (428 × 292 mm) to access the oil and water pumps, a single water drain, two drains for the oil tanks, two fuel drains, and a hatch to drain the oil from a gearbox housing (Ø 300 mm). These drains were closed by armored plugs, while the access hatches were closed by the bolted on armored panels. Along the edges on both sides the hull bottom had four openings for inspection and in-stallation of the roadwheels’ suspension parts. The bottom edge of the four suspension spring housings were welded to the edges of the openings from inside of the hull.

The roof of the hull could be split into three main sec-tions: the roof over the fighting compartment, over the en-gine compartment and over the transmission compartment. All parts of the hull’s roof were made of 20 mm thick rolled homogenous armor of the grade 2-P (MZ-3). The roof over the fighting compartment was made out of two armor plates (parts #34.29.1704 and #34.29.1705) of the same thickness, which were connected with a butt weld joint. It had a round opening (Ø 1481 mm) for the installation of the turret; holes for the turret ring bolts; and four cut-outs for access to the upper parts of wheel suspensions, closed by lids. Unlike the fighting compartment roof, the roof of the engine compart-ment was removable. It consisted of a middle longitudinal plate (part #34.29.849) above the engine and two lateral lon-gitudinal plates (parts #34.29.850 and #34.29.851) above the cooling radiators. The middle plate over the engine had a washtub-shaped form with a bulge facing up; the side and rear walls of the “upside-down tub” were reinforced by weld-ed on 20-mm thick armored planks. For access to the engine, the top of the plate had a large opening (800 × 500 mm) cov-ered with a lid (part #34.29.050) on two hinges; the lid cover had a special lock. To allow the air passage, both roof plates over the radiators had longitudinal openings (“windows”) in the middle; the “windows” had vertically positioned non-ad-justable armored louvers welded to the transverse webs.

Both plates also had smaller round holes closed by armored caps; these were used to fill the oil tanks. Armored covers with bars (part #34.29.053 and #34.29.054) were installed over the louvers.

The roof over the transmission compartment also con-sisted of several armor plates: two plates (parts #34.29.014 and #34.29.015) above the fuel tanks, two plates serving as air exhaust louvers (parts #34.29.037) above the fan, and a narrow transverse armor plate (part #34.29.035). The ar-mored louvers were adjustable and could be fixed in one of three positions. The hand lever for the louvers’ drive was controlled by the driver; the lever was moved along a spe-cial sector installed on the housing of the second left road wheel suspension. The transmission compartment roof was protected from foreign objects by a mesh cover; the cover could be flipped open when access was needed. The roof of the transmission compartment also had two small hatches for access to the filler tubes of the fuel tanks; located under the cover, they were closed by armored lids.

(Cont. in the next issue)______* From the Russian abbreviation “ЗИП” - Запасные части, Инструменты

и Принадлежности (spare parts, tools and accessories).** Plural form of the noun “zadraika” from the Russian verb “задраивать”

meaning to batten down [the hatches].*** From the Russian abbreviation “МПБ” – Механизм Поворота Башни

(turret traverse mechanism).___________________________________________________From the publisher: The colored photos and blueprints on the pages 21, 23 and 25-26 were not included in the original version of the article, and were added by the publisher to better illustrate details that may require an additional explanation.

Sketch of the bottom of T-34 hull Plant No.183 production with numbers of the armored parts as of July 1, 1942. (RGAE)

design and layout of t-34 tanks

Documents

drivers compartment

medium tank

drivers hatch

tank commander

fighting compartment

engine compartment

hatch cover

armored hatch