T - 35 The T - 35 was a Soviet multi - turreted heavy tank of the interwar period and early Second World War that saw limited production and service with the Red Army . It was the only five - turreted heavy tank in the world to reach production , but proved to be slow and mechanically unreliable . Most of the T - 35 tanks still operational at the time of Operation Barbarossa were lost due to mechanical failure rather than enemy action . Outwardly , it was large ; but internally , the spaces were cramped with the fighting compartments separated from each other . Some of the turrets obscured the entrance hatches . Production history . The T - 35 was developed by the OKMO design bureau of the Bolshevik Factory , which began work on a heavy tank in 1930 . Two teams developed separate designs . The team headed by German engineer Grotte worked on the 100 - ton four - turreted TG - 5 tank , armed with a 107 mm naval gun , using pneumatic servo - controls and pneumatic suspension . This project was later cancelled . The concept of large , multi - turreted breakthrough tanks was favoured by several European armies in the 1920s and 1930s . Designs existed in Britain , France , and Germany for such vehicles . The second OKMO team , headed by N . Tsiets , worked on a tank inspired by the British Vickers A1E1 Independent . By July 1932 , a prototype of a 35 ton tank with a 76 . 2 mm tank gun was completed . The first prototype was further enhanced with four smaller turrets , two with 37 mm guns and two with machine gun s . This first prototype had severe defects in its transmission and was considered too complex and expensive for mass production . Therefore work on it was stopped and a new simpler prototype was built . This new prototype received a new engine , new gearbox and improved transmission . The decision was also made to standardise the turrets used on the T - 35 with those employed on the T - 28 , a triple - turreted medium tank . The small machine - gun turrets were identical on the two tanks . The large main turret housing the 76 . 2 mm gun was nearly identical , but those used on the T - 28 had an additional , rear - firing machine gun . On 11 August 1933 , the T - 35 was accepted for production . Engineering was shifted to the Kharkov Locomotive Factory , and two batches of ten vehicles were completed . The experiences gained with the two prototypes were used for the main production T - 35 Model 1935 , which was again improved from the second prototype , with a longer chassis , improved hull and 45 - mm guns in place of the 37s . It started production in 1935 , and about 35 were built by 1938 . In general , throughout its production run small improvements were made to the individual tanks . Production tanks had turrets similar to the ones on the BT - 5 , but without the rear overhang . Some examples had flamethrowers instead of one of the 45 mm guns . The final batch was a run of six T - 35 Model 1938s , which had new turrets with sloped armour all around , as well as modified side skirts and new idler wheels . Originally , the main turret was equipped with a 76 . 2mm gun KT obr . 1927 / 32 adapted from the regimental field - gun obr . 1927 . By 1936 , this weapon was being replaced by the KT - 28 cannon ( length of barrel 16 . 5 calibers ) , which was also used on the Т - 28 medium tank . The mounting allowed for vertical training ( aiming ) with upper and lower limits of - 7° and + 23° , respectively . As an auxiliary weapon in the main turret , to the right of the cannon , the 7 . 62mm DT machine gun was placed autonomously in a ball setting . The cannon and machine gun had complete 360° horizontal sector of fire and independent fire control systems . The spare DT machine gun was fastened in a loop setting in the storage niche of the turret . The mechanism to turn the turret employed an electromechanical three - speed drive ; an auxiliary hand drive was also provided for emergency use . By 1937 , an anti - aircraft DT machine gun was set in a P - 40 mount on the foundation of the gunners hatch on the main turret . In 1938 , the L - 10 tank cannon was proposed for the main turret weapon , but the representatives of the ABTU ( the " Auto - Tank Directorate " ) abandoned this idea , considering the power of the KT - 28 enough for the purpose of defeating enemy armored vehicles , and the accompaniment of attacking infantry was provided for by the two 45 - mm cannons . In each of the two diagonally - mounted ( i . e . , one in the right forward quarter and another in the diagonally - opposite left rear quarter , as viewed from behind ) two - seater turrets was placed one 45mm tank cannon obr . 1932 and a coaxially - mounted 7 . 62mm DT machine gun . Later , this cannon was replaced with a 45mm gun of the 20k Model 1934 with a semi - automatic breech - block . The coupled setting had vertical training ( aiming ) limits of - 8° to + 23° . The front turret weapon had a horizontal field of fire from 19° ( left of the turret ' s centerline ) to - 184° ( rearwards ) . The two smaller turrets were single - seat and had one 7 . 62mm DT machine gun apiece . The horizontal training ( aiming ) of these weapons was carried out through the turning of a hand mechanism . The main and the two small machine gun turrets of the Т - 35 and Т - 28 had a high level of standardization . Main - weapon sighting utilized the telescopic breech - sight TOP obr . 1930 and the periscope breech - sight PT - 1 обр . 1932 . The 76 . 2mm cannon had 96 rounds , the 45mm guns had 226 rounds , and the DT machine guns had 10 , 080 cartridges . The 50 - ton tank was designed with the maximum thickness of the body ' s armoured plates being 30mm and that of the turret 20mm . The armoured plates were coupled together by welding and riveting . In 1936 the thickness of the frontal , sloping body plate and the front plate protecting the driver - mechanic was increased to 50mm . Armored side skirts also added 10mm to the side armor covering the tracks . In 1938 , a conical turret with a maximum thickness of 25mm ( at the front ) for strengthening the armoured defence of the tank was introduced ; the thickness of the frontal armoured plates was also increased , to 70mm . The battle weight of the machine grew to 54 tons ( the first - series machines weighed 42 . 5 tons ) . Overall , from April 1939 to the end of Т - 35 production , six machines with the increased armoured defence were produced . On two of the machines of the 1939 issue , a 7 . 62 - mm DT machine gun was mounted in the storage portion of the main conical turret back , for rear defence . Western and Russian historians disagree about the inspiration for the T - 35 ' s design . The former argue it was inspired by the British Vickers A1E1 Independent tank , but this is rejected by many Russian specialists . It is impossible to know the truth , but there is strong evidence to support Western claims , not least failed Soviet attempts to purchase the A1E1 . At the same time , the influence of German engineers , who in the late 1920s were developing similar designs at their Kama base in the Soviet Union , cannot be discounted . What is clear is that borrowing military technology and ideas from other nations was common to the majority of the armed forces in the inter - war years . The Red Army , with its purchase of the British Vickers Carden Loyd tankette , Vickers E - Light and Cruiser Mk II Medium tanks , and of the American Christie suspension for production use in its own vehicles , was clearly one of the leading exponents of this practice . Due to its high cost , the production run of the T - 35 ended at just sixty - one tanks . Combat history . The T - 35 served with the 5th Separate Heavy Tank Brigade in Moscow , primarily for parade duties , from 1935 until 1940 . In June 1940 , the question was raised whether to withdraw the T - 35s from frontline service , with the option to either convert them to heavy self - propelled artillery , or to assign them to the various military academies . The choice was made to use them up in combat instead and the surviving vehicles were collected together into the 67th and 68th Tank Regiments of the 34th Tank Division , which served with the 8th Mechanized Corps in the Kiev Special Military District . During Operation Barbarossa , ninety percent of the T - 35s lost by the 67th and 68th Tank Regiments were lost not to enemy action but through either mechanical failure or because they were abandoned and destroyed by their crews . The most common causes of breakdown were transmission - related . The last recorded action of the T - 35 took place during the early stages of the Battle of Moscow . At least one captured T - 35 was shipped to Germany for evaluation at the Kummersdorf military proving ground . The T - 35 is sometimes cited as having participated in the Winter War against Finland , but according to Soviet sources it did not . In fact , two other prototypes of multi - turreted heavy tanks had been sent to the front for testing : T - 100 and SMK . The SMK tank was disabled by a Finnish land mine and all attempts to recover the 55 - ton behemoth failed . Finnish photographs of the previously unknown tank were mistakenly designated " T - 35C " by German intelligence . Four T - 35 machines were used in training facilities in the Soviet rear . One of these still exists in running condition and is accessible to visitors at the Kubinka Tank Museum near Moscow .