Military Review

Project wheel-tracked tank A-20

In the thirties, Soviet tank builders were actively developing wheel-tracked vehicles. tanks. Due to certain problems with the resource of the caterpillar mover, I had to look for an alternative solution, which eventually became the use of a combined chassis. In the future, problems with the tracks were resolved, which led to the abandonment of wheeled-tracked tanks. After that, all domestic armored vehicles of this class were equipped only with a caterpillar mover. However, in the mid-thirties there were no necessary technologies and materials, which forced designers to study and develop several projects at the same time.

Even before the end of the war in Spain, the Soviet military and designers began to discuss the appearance of a promising tank. The rapid development of anti-tank artillery led to the emergence of a requirement to equip machines with anti-bullet armor resistant for 37 and 45 caliber guns. There were common views on the armament of promising tanks. The reason for numerous disputes was the chassis. The specialists divided into two camps, which defended the need to use a tracked or combined propulsion unit.

Project wheel-tracked tank A-20
Experienced A-20

The main prerequisite for the creation of wheeled-tracked tanks was the low resource of the tracks that existed at that time. The military wanted a tracked drive with a resource of at least 3000 km. In this case, it was possible to abandon the idea of ​​hauling equipment over long distances using wheels. The lack of required tracks was an argument in favor of a combined propulsion unit. At the same time, the wheel-tracked scheme complicated the design of the tank, and also had a negative impact on production and operation. In addition, foreign countries by this time began the transition to a full-fledged tracked vehicles.

October 13 1937, the Kharkov Locomotive Plant them. Comintern (KhPZ) received a technical task for the development of a new wheeled-tracked tank. This machine was supposed to have six pairs of drive wheels, combat weight at the level of 13-14 t, antislite armor with inclined arrangement of sheets, as well as 45-mm cannon in a rotating turret and several machine guns. The project received the designation BT-20.

In March, 1938, Commissar of Defense K.E. Voroshilov made a proposal concerning the future of armored units. In a memo addressed to the chairman of the Council of People's Commissars, he noted that tank units needed only one tank. To determine the most profitable version of such a machine, the People's Commissar proposed to develop two similar projects of tanks with different propulsion units. Having the same protection and armament, the new tanks were to be equipped with wheel-tracked and tracked propellers.

By September 1938, Kharkov engineers had completed the development of the BT-20 project and presented it to the specialists of the People's Commissariat of Defense. The staff of the Armored Directorate reviewed the project and approved it, making some suggestions. In particular, it was proposed to develop a version of the tank with the 76-mm gun, to provide for the possibility of circular observation from the tower without using viewing devices, etc.

Further work was carried out taking into account the proposals of the ABTU. Already in October, 38-th KhPZ presented a set of drawings and models of two promising medium tanks, which differed in the type of running gear. The main military council examined the documentation and models in early December of the same year. Soon, the preparation of working drawings for a wheeled-tracked tank began, by which time it had received the new designation A-20. In addition, the design of the tracked vehicle called A-20G was launched. In the future, this project will receive its own name A-32. The lead engineer of both projects was A.A. Morozov.

At this stage of the implementation of the two projects, serious disagreements arose. In the fall of 38, the military agreed on the need to build and test two experimental tanks. However, at a meeting of the 27 Defense Committee in February 1939, the representatives of the Defense Commissariat subjected the A-32 tracked tank to serious criticism. The wheel-tracked A-20, as it was then thought, had greater operational mobility. In addition, the current status of the project A-32 left much to be desired. As a result, doubts arose about the need to build and test a tracked vehicle.

However, the chief designer of KhPZ M.I. Koshkin insisted on the need to build two prototypes. According to various sources, the military offered to close project A-32 due to the impossibility of quickly completing its development and building a prototype within an acceptable timeframe. However, M.I. Koshkin was able to convince them of the need to continue the work and, as it turned out, he was right. In the future, the A-32 after the mass of improvements was adopted under the symbol T-34. The medium tank T-34 was one of the most successful combat vehicles of the Great Patriotic War.

Tank A-20 in a number of ways lost to its caterpillar counterpart, however, it is of great interest with technical and historical points of view. So, he became the last wheeled and tracked tank of the Soviet Union. In the future, the problem of unacceptably high wear of the tracks was solved and abandoned the combined chassis.

Medium tank A-20 was built on the classic layout. In front of the armored hull there was a driver (at the left side) and an arrow. Behind them there was a fighting compartment with a tower. Stern hull given under the engine and transmission units. The tower provided for jobs commander and gunner. The commander of the car also performed the duties of the loader.

The armored vehicle had a welded construction. It was proposed to collect from several armor sheets with a thickness of 16-20 mm. To increase the level of protection, the hull sheets were located at an angle to the vertical: the front sheet — under 56 °, the sides — 35 °, and the aft — 45 °. The welded tower was made of sheets with a thickness of up to 25 mm.

Reservations with a thickness of up to 25 mm, located at rational angles, made it possible to provide protection against bullets of large-caliber small weapons and small-caliber artillery, as well as to maintain the combat weight of the machine at the level of 18 t.

At the rear of the hull there was a B-2 diesel engine with 500 horsepower. The transmission consisted of a four-stage three-speed gearbox, two side clutches and two single-row final drives. The use of wheel-track propulsion impacted the design of the transmission. For the movement on the tracks, the machine had to use the drive wheels with a ridge engagement located in the stern. In the wheel configuration, three rear pairs of road wheels became the driving wheels. An interesting fact is that the BT-20M armored vehicles were widely used as part of the transmission of the A-7 tank.

The chassis of the medium tank A-20 had four support rollers on board. In the front part of the hull, the guide wheels were mounted, in the aft - leading wheels. Basic skating rinks were equipped with an individual spring suspension. Three rear pairs of rollers were associated with the transmission and were leading. The two front wheels had a turning mechanism to control the vehicle when driving “on wheels”.

In the turret of the tank installed 45-mm tank gun 20-K. Inside the fighting compartment, we managed to place an 152 projectile for the cannon. In one installation with a gun mounted twin machine gun DT caliber 7,62 mm. One more machine gun of the same type was in spherical installation of a frontal sheet of the body. The total ammunition of two machine guns - 2709 cartridges.

A-20 tank gunner had a telescopic and periscopic sights. Mechanisms with electric and manual drives were used to target the gun. The commander of the vehicle could monitor the situation on the battlefield with his own panorama.

Communication with other tanks and units was provided with the help of 71-TK radio station. The crew of the car was supposed to use the TPU-2 tank intercom.

At the beginning of the summer of 1939, Plant No. 183 (a new name for KhPZ) completed the construction of two experimental tanks A-20 and A-32. The wheel-tracked vehicle was handed over to the military representative office of ABTU 15 June 39. Two days later, the military handed over the second experienced tank. After some preliminary checks on 18 July, comparative field tests of the new tank started, which continued until August 23.

Medium tank A-20 showed quite high performance. On a wheeled course, he developed speeds up to 75 km / h. The maximum speed on the tracks on a dirt road reached 55-57 km / h. When driving on a highway, the range was 400 km. The car could climb the 39-degree slope and wade through water obstacles to a depth of 1,5 m. During the tests, the prototype A-20 passed along different 4500 km routes.

Experienced A-32

The test report stated that the A-20 and A-32 tanks presented surpass all existing serial vehicles in a number of characteristics. In particular, there was a significant increase in the level of protection in comparison with old equipment. It was argued that rational angle of armor and other design features provide greater resistance to shells, grenades and flammable liquids. The crossover of the A-20 and A-32 was superior to the existing BT series tanks.

The commission that conducted the tests concluded that both tanks met the requirements of the Defense Commissariat, so that they could be put into service. In addition, the commission made a proposal concerning the design of the tank A-32. This machine, which had a certain margin for weight gain, after minor modifications could be equipped with more powerful armor. Finally, the report pointed out some of the shortcomings of the new armored vehicles that needed to be addressed.

New tanks were compared not only with serial, but also with each other. During the tests, some advantages of A-20 in terms of mobility were found out. This machine has proven its ability to make long marches with any undercarriage configuration. In addition, the A-20 retained the desired mobility with the loss of tracks or damage to two road wheels. However, there were drawbacks. The A-20 was inferior to the tracked A-32 in terms of firepower and protection. In addition, the wheeled-tracked tank had no reserves for modernization. His chassis was heavily loaded, because of which, with any noticeable modifications to the car, it would have to be developed anew.

19 September 1939, the People's Commissariat of Defense made a proposal to adopt two new medium tanks for the Red Army. Before starting the assembly of the first production machines, the designers of the plant # XXUMX recommended fixing the identified deficiencies, as well as slightly changing the design of the hull. The front sheet of the hull should now have a thickness of 183 mm, the front part of the bottom - 25 mm.

By December 1, 1939 was required to build an experimental batch of A-32 tanks. The design of the first ten machines planned to make some adjustments (project A-34). A month later, Kharkov specialists had to transfer to the military the first 10 tanks A-20, also in a modified version. Full-scale mass production of A-20 was supposed to begin with 1 March 1940 of the year. The annual release plan was set at the level of 2500 tanks. The assembly of new tanks was to be carried out by the Kharkov plant No. XXUMX. Production of armor parts were going to entrust the Mariupol Metallurgical Plant.

Experienced tanks at the site in Kubinka. From left to right: BT-7M, A-20, T-34 arr. 1940, T-34 arr. 1941

The development of the updated project A-20 has been delayed. Kharkiv plant was loaded with orders, because of which the creation of a modernized project was associated with certain difficulties. New design work began in November 1939. It was planned to test the upgraded A-20 with enhanced armor and undercarriage at the very beginning of 40. Soberly assessing its capabilities, Plant No. 183 appealed to the management of the industry with a request to transfer the serial production of А-20 to another company. Kharkov plant could not cope with the full-scale production of two tanks at the same time.

According to some reports, work on the A-20 project continued until the spring of 1940. Plant No.183 had certain plans for this project, and also wished to transfer the construction of serial tanks to another enterprise. Apparently, those wishing to start the production of new medium tanks were not found. In June, the Politburo of the CPSU (B) issued a decree of 1940, in accordance with which it was required to begin mass production of medium-sized T-34 tanks (former A-32 / 34) and heavy KVs. Tank A-20 in the series did not go.

There is some information about the further fate of the only built experienced tank A-20. At the beginning of World War II, this machine was included in the tank company of Semyonov, which, according to some sources, was formed from the equipment available at the test site of the 22 th Scientific test vehicle and armored range (now 38 th Research Institute of the Ministry of Defense, Kubinka). In the middle of November, the X-NUMX prototype A-1941 completed the 20-th tank brigade. December 22 car received minor damage and after a few days returned to service. For several weeks the 1 Brigade carried out combat missions together with the cavalry of Major-General L.М. Dovatora. In mid-December, the A-22 tank was again damaged, after which it was relegated to the rear for repair. At this traces of an experienced car are lost. Her further fate is unknown.

Medium tank A-20 did not go into the series. Nevertheless, its development, construction and testing were of great importance for the domestic tank building. Despite the not quite successful completion, this project helped to establish real prospects for tracked and wheeled-tracked vehicles. Tests of A-20 and A-32 tanks showed that with existing technologies, armored vehicles with a combined undercarriage are rapidly losing advantages over tracked vehicles, but cannot get rid of congenital defects. In addition, A-32 had a certain stock of characteristics for upgrading. As a result, the updated A-32 tank went into series, and the A-20 did not leave the test and refinement stage, becoming the last Soviet wheeled-tracked tank.

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  1. igordok
    igordok 12 May 2015 07: 38
    The commander of the machine also performed the duties of the loader.

    In T-34, the commander was also a gunner. Both options, where the commander is distracted from observation and leadership, are bad. But if you use a commander, which option is better, A-20 or T-34?
    In the loader's version, there is more "free time", but the workplace is inconvenient for observation.
    In the version of the gunner, the gunner is already monitoring the battlefield, though in a narrow sector.
  2. Gray 43
    Gray 43 12 May 2015 07: 58
    Everything is known about the ancestor of the famous T-34, but a little about his rival, thanks to the author for the article
  3. inkass_98
    inkass_98 12 May 2015 09: 01
    A-20 was interesting in terms of the development of Christie’s technology, but would not have been successful in terms of further modernization, it didn’t have the same potential as A-32 because of the wheel-caterpillar mover.
    1. svp67
      svp67 12 May 2015 11: 17
      Quote: inkass_98
      A-20 was interesting in terms of the development of Christie’s technology, but would not have been successful in terms of further modernization, it didn’t have the same potential as A-32 because of the wheel-caterpillar mover.

      I do not agree. The potential was. As they once refused the opportunity to sail with the T40 and created its completely normal modification, they could have created a new light tank similar in design to the T34 by abandoning the Wheel-Caterpillar mover, which would greatly simplify the supply and organization of repairs ...
    2. Argon
      Argon 12 May 2015 11: 55
      A-20 is the most vivid example of unwillingness, fear (caused by incompetence) of the responsibility of making a decision, by the top leadership of the Red Army, which is not surprising, all those who could have either sat or were shot. Does this experiment remind you of solving the problem, is it better to roll a ball or a cube? In the 39th year, everything was already very clear, on the one hand, the "Spanish" experience, on the other hand, the comparative operation of the experimental series T-29 (wheeled-tracked) and T-28 (purely tracked).
    3. goose
      goose 12 May 2015 13: 51
      The BT-7m was exploited almost 100% on the tracks, their removal was no longer foreseen. Whereas the BT-7 still had this opportunity. This is an indicator of opinion that prevailed in tests A-20 and A-32. Just the day before, the technological problem of hardening the hinges of the tracks for the T-26 (and the rest) was solved, thanks to which the resource of the tracks was more than 2000 km, instead of 300 earlier. This was confirmed by operation in units and a report on this was already available at the GABTU.
  4. Malkor
    Malkor 12 May 2015 10: 33
    Plant No. 183 realized that the A20 project was rotten and tried to shove it to another plant, only for this he was tasked with bringing the A20 to mind before mass production, which the factory could not cope with. My opinion for the tank is caterpillars, if you need a wheeled chassis, you had to create a whole wheeled car.
    1. DmitriyDonskoj
      DmitriyDonskoj 12 May 2015 11: 27
      There were problems with wheels then - only natural rubber, with caterpillars too - wear resistance suffered, until superhard alloys (Pobedite) appeared for another 20 years, but they could not be serially treated with high-speed steel (rapid) for a long time. So I had to be wise.
      1. washi
        washi 12 May 2015 12: 26
        Quote: DmitriyDonskoj
        There were problems with wheels then - only natural rubber, with caterpillars too - wear resistance suffered, until superhard alloys (Pobedite) appeared for another 20 years, but they could not be serially treated with high-speed steel (rapid) for a long time. So I had to be wise.

        And they couldn’t make a box of speeds on their own, but could they deploy the engine? All this was done, but later not by T-44 Kharkiv.
        And the rubber on the rinks, the increased shoulder strap of the tower - at first they did without it. Look at the photo of the T-34 1942-43gg. Due to the low technological effectiveness of Kharkov developments, every Lepid plant as it could. It later came to a common denominator
      2. goose
        goose 12 May 2015 13: 47
        Quote: DmitriyDonskoj
        There were problems with wheels then - only natural rubber, with caterpillars too - wear resistance suffered, until superhard alloys (Pobedite) appeared for another 20 years, but they could not be serially treated with high-speed steel (rapid) for a long time. So I had to be wise.

        What is natural rubber? In the USSR, there was never any currency on it.
        In 1910, Ivan Kondakov discovered the polymerization reaction of dimethylbutadiene. In Russia and the USSR, Nikolai Vavilov worked on this problem. Synthetic rubber serial tires.
        .In 1926, the Supreme Council of the National Economy of the USSR announced an international competition for the best industrial method of producing synthetic rubber. Scientists from all countries could participate in it. Main conditions: artificial rubber must be of high quality, cheap and made from domestic raw materials.
        Two methods have been adopted for the production of synkatchuk; their authors are our scientists S. V. Lebedev and B. V. Byzov. By the method of Academician S.V. Lebedev, synthetic rubber is obtained from ethyl (wine) alcohol, and by B.V. Byzov's method - from oil. Already in 1931-1932. In our country, powerful synthetic rubber plants were built and put into operation for the first time in the world.

        Synthetic rubber was first created in our country in Leningrad in 1928. And in 1932, the Red Triangle plant mastered its industrial production (6 years earlier than in Germany, and 10 years earlier than in the USA). He worked according to the Lebedev method.

        In addition, there were rubber plants in the USSR, the most famous being ordinary dandelion.
  5. washi
    washi 12 May 2015 10: 58
    10 th
    The armor of the BT-7M was strengthened (even the engine was not changed). That's all design (it’s hard to call it construction), although what do you want from Kharkov tank builders? They were noted after the war with their T-64.
    T-34 (A-32) began to drive normally only after tuning carried out at Russian plants.
    1. DmitriyDonskoj
      DmitriyDonskoj 12 May 2015 11: 28
      Have you designed a lot?
      1. washi
        washi 12 May 2015 12: 23
        Quote: DmitriyDonskoj
        Have you designed a lot?

        Nothing. I exploited according to the diploma
    2. alecsis69
      alecsis69 13 May 2015 03: 16
      In general, the BT-7M differed from the BT-7 in the first place with a diesel engine, which then stood on all medium and heavy Soviet tanks, taking into account improvements to the T-90 inclusive, with the exception of the T-64, well, the T-80 is natural.
  6. svp67
    svp67 12 May 2015 11: 13
    Alas, but the author in this article "dug not deeply, and not widely."
    Where is the mention of the names of Dil, Firsov, and many more who have laid down the concept of both the A-20 and the T32 ... Silence. Again, great Koshkin. But his main merit is that he was an excellent organizer and tough at the same time. He did a lot to make these tanks born, in the end he gave his life for it. But do not forget those who gave their lives and health in dungeons and camps, on false accusations ... Why don’t they remember them now?
    Nevertheless, the chief designer of KhPZ M.I. Koshkin insisted on the need for two prototypes.
    Another myth. If he could "insist" on this, it was only in the form of reports addressed to the director of the plant and his People's Commissar. The decision was made by completely different people and for some reason their names are now forgotten. And apparently it is worth remembering the name of Pavlov's NachAvtoBroneTank Directorate, who "moved" these tanks, for the mistakes of the first days of the war he already answered in full, why not tell him "THANKS" for the T34, then he was right.
  7. washi
    washi 12 May 2015 12: 35
    Thanks to Pavlov for the tanks. And for the failure to comply with the directive of 18.06. he is not shot enough
    1. Argon
      Argon 13 May 2015 00: 08
      There were so many of these directives and often mutually exclusive. 22.06.41 7 of them were received, from- "not to give in to provocations" -to- "immediately develop an offensive on Krakow" -.
  8. whereispie
    whereispie 12 May 2015 13: 57
    Great article ..
  9. valerysvy
    valerysvy 12 May 2015 14: 09
    Thank you ... Interesting ... the photo of 4 tanks at the test site is simply a "masterpiece"
  10. fa2998
    fa2998 12 May 2015 14: 54
    Already at the end of the 30s, the A-20 was morally obsolete. The rich experience of military cock conflicts (including Spain) showed that tanks with 15-25mm armor. Are easily hit by anti-tank guns of the smallest calibers (37,40,42,45). The Germans began to shield them. tanks, and did not help much. Near Moscow they were beaten from the PTR cal.14.5mm. It is correct that they rejected this "brother" BT and thanks for the T-34. We thought right! The Germans should come later, and in the midst of the war, the production of "Panthers" and "Tigers". hi
  11. Free wind
    Free wind 12 May 2015 20: 29
    Thanks to comrade KOSHKIN, FOR HIS GENIUS CREATION, for his T-34 tank, contrary to all generals, Thanks to comrade STALIN for seeing the future in this car. !!!!! T-34 had many shortcomings, but was able to fight !!!!