T - 26 variants Main article : " T - 26 tank " More than 50 different modifications and experimental vehicles based on the T - 26 light infantry tank chassis were developed in the USSR in the 1930s , with 23 modifications going into series production . The majority were armoured combat vehicles : flame tank s , artillery tractor s , radio - controlled tanks ( teletank s ) , military engineering vehicles , self - propelled gun s and armoured personnel carriers . They were developed at the Leningrad Factory of Experimental Mechanical Engineering ( from 1935 known as the Factory No . 185 named after S . M . Kirov ) by talented Soviet engineers P . N . Syachentov , S . A . Ginzburg , L . S . Troyanov , N . V . Tseits , B . A . Andryhevich , M . P . Zigel and others . Many Soviet tank engineers were declared " enemies of the nation " and repressed during Stalin ' s Great Purge from the middle of the 1930s . As a result work on self - propelled guns and armoured carriers ceased in the USSR during that time . T - 26 light tanks were also modified into armoured combat vehicles in the field during wartime . Flame - throwing ( chemical ) tanks . Flame - throwing tanks formed around 12 % of the series production of T - 26 light tanks . It should be mentioned that the abbreviation " OT " ( " Ognemetniy Tank " which stands for " Flame - throwing Tank " ) appeared only in post - war literature ; these tanks were originally called " KhT " ( " Khimicheskiy Tank " which stands for " Chemical Tank " ) , or BKhM ( " Boevaya Khimicheskaya Mashina " ; " Fighting Chemical Vehicle " ) in the documents of 1930s . All chemical ( flame - throwing ) tanks based on the T - 26 chassis ( KhT - 26 , KhT - 130 , KhT - 133 ) were designated BKhM - 3 . The vehicles were intended for area chemical contamination , smoke screens and for flame - throwing . The TKhP - 3 chemical equipment for smoke screens and chemical contamination was developed in 1932 . This equipment could be easily installed on any T - 26 light tank and was produced by the " Compressor " Factory , ( introduced for smoke screening as the TDP - 3 from summer 1934 ; 1 , 503 such sets were produced to the end of 1936 ) . Combat engineer vehicles . Additional variants of the ST - 26 ( with a sliding system of bridge laying and with a tipping system of bridge laying ) were also tested from 1932 . The first had a massive guide frame and a special boom ( the bridge could be laid in 3 min 20 sec , the raise operation took 6 - 7 min ) , while the second was equipped with a special swinging - boom with a rack - and - pinion drive . All three variants of the ST - 26 participated in military maneuvers of the Leningrad Military District in the summer of 1933 ; subsequently series production of the ST - 26 with a cable system of bridge laying was begun as it proved to be more reliable and less complicated to maintain . The Defence Committee of the USSR ordered the production of 100 ST - 26 to the end of 1933 , but only 44 vehicles were assembled by the Factory No . 174 by 1934 , and 20 in 1935 . The delay was attributed to the manufacture of the metal bridges , carried out by the " Gipstalmost " Factory and several workshops using semi - handicraft techniques . " Specifications " : weight - ; crew - 2 men ( commander and driver ) ; speed - ; range - . The Armoured Engineering Section of the Red Army ' s Research Institute of Engineer Equipment ( NIIIT RKKA ) in co - operation with the " Gipstalmost " Factory developed an improved engineer tank at the end of 1936 , with a lever hydraulic system of bridge laying ( similar to the UST - 26 , see below ) and a small turret of new design . The bridge could be laid in 45 sec and the raise operation took 1 . 5 min ( both processes did not require crew exit ) . The vehicle was assembled by the Podolsk Machine Factory named after S . Ordzhonikidze in July 1937 , and was successfully tested at the NIIIT Proving Ground ( 85 bridge layings were performed and 70 light tanks passed over the bridge ) . This ST - 26 prototype was also tested at the Kubinka Tank Proving Ground , and participated in military exercises of the Leningrad Military District in 1938 . A decision was made in 1939 to produce a batch of engineer tanks with the lever hydraulic system , but the Podolsk Machine Factory could assemble only one . The Stalingrad Tractor Factory probably also produced two such vehicles the same year . An experimental multispan bridge was developed in 1934 which allowed for the coupling together of three or more ST - 26 bridges , using special automatic grips in the end of each bridge section . The multispan bridge employed 250 kg metal columns high and was intended for crossings by T - 26 and BT light tanks of water obstacles up to wide and deep . The launching of each bridge section took 20 - 30 min . The bridge had no development after testing . Engineer Alexandrov from the Research and Technology Division of the Red Army ' s Engineer Directorate ( NTO UNI RKKA ) developed a wooden tracked bridge long . The bridge was mounted on standard T - 26 light tanks as well as on ST - 26 engineer tanks and could be laid in 30 - 60 sec without crew exit . Trials carried out in July – August 1934 were successful and 20 such bridges were issued to the armed forces . Seventy - one ST - 26 engineer tanks were produced in 1932 - 1939 including experimental vehicles : 65 ST - 26 with a cable - laid bridge system , 1 ST - 26 with a sliding bridge , 1 ST - 26 with a tipping bridge , 2 UST - 26 and 2 ST - 26 with a levered bridge - laying system . Ten ST - 26 engineer tanks were used on the Karelian Isthmus during the Winter War ( 9 with a cable system and 1 with a lever system ) ; they were included in engineer groups for obstacle clearing that were established in each tank brigade during the war . Three ST - 26 tanks of the 35th Light Tank Brigade had the most success ( in particular they launched two bridges over a trench and then an antitank ditch for a tank battalion during an assault on the fortified High Point 65 . 5 ( Hottinen area ) of the Mannerheim Line on February 18 , 1940 ) . The ST - 26 with the lever system of bridge laying demonstrated good results and that vehicle was used quite actively during the Winter War , while tanks with the cable system were less reliable and had limited use . There were no losses of ST - 26 engineer tanks during the Winter War . Tank units of the Red Army had 57 ST - 26 engineer tanks on June 1 , 1941 : 9 in the Far Eastern Front , 26 in the Moscow Military District , 2 in the Leningrad Military District , 2 in the Kiev Special Military District , 8 in the Western Special Military District , 1 in the Volga Military District , and 9 vehicles were in military supply depots . From those ST - 26 engineer tanks only 12 were in good order , the others required repair . Artillery tractors . " Specifications " : weight - ; crew - 1 ( driver ) + 4 - 5 ( gun crew or landing party ) ; armour - ; speed - , with a 5 - t trailer ; range - with a 5 - t trailer . One hundred and eighty three T - 26T were produced in 1933 . Fourteen more with a high - powered engine and improved towing device were produced in 1936 ( including 10 with an armoured cabin ) . The manufacturer was the Factory No . 174 named after K . E . Voroshilov in Leningrad ( a plan to produce 200 T - 26T with a canvas cover and 150 T - 26T with an armoured cabin annually was not carried out due to increases in tank production ) . Tests and army service showed that T - 26T artillery tractors were underpowered for cross - country towing of trailers weighing more than , so these vehicles had no further development . Also around 20 T - 26 light tanks of early models were converted into artillery tractors by army units in 1937 - 1939 . A transfer of overhauled old twin - turreted T - 26 tanks ( without turrets and armament ) from some tank units of western military districts for use as artillery tractors for anti - tank and regimental guns in mechanized corps began in May 1941 . Tank and mechanized infantry units of the Red Army had 211 artillery tractors based on the T - 26 chassis on June 1 , 1941 . Almost all T - 26T artillery tractors of border and some inner military districts were lost during the first weeks of the Great Patriotic War . A few remained in front - line service until 1942 at least ( for example , the 150th Tank Brigade of the Bryansk Front had a T - 26T with an armoured cabin on May 15 , 1942 , which was used as a command vehicle ) . No less than 50 old twin - turreted T - 26 tanks of the Transbaikal Military District were converted into artillery tractors from 1941 ; these vehicles participated in combat with the Japanese Kwantung Army in August 1945 . Armoured carriers . " Specifications " : full weight - ; crew - 2 ( driver and commander ) + 14 men ( landing party ) ; armour - . Series production . Around 1 , 701 armoured combat vehicles based on the T - 26 chassis were produced in the USSR from 1932 till 1941 . Vehicle - mounted engineer equipment . Many different attached implements for the T - 26 light tank were developed in the USSR in the 1930s . Among these were mine sweeps , equipment for swimming , snorkels for deep fording , wooden and brushwood fascines for trench crossing , special extra - wide swamp tracks and mats , wire cutters , dozer blades and many others . All of them were tested but despite often excellent test results none ( except some mine sweeps ) passed into army service . Design work started again when the Winter War began : Leningrad factories Kirov Factory , Factory No . 185 and Factory No . 174 developed new models of mine sweeps for the T - 26 and T - 28 tanks in December 1939 . Kirov Factory produced 93 new mine sweeps and Factory No . 174 produced an additional 49 . These disc mine sweeps ( metal discs 700 – 900 mm in diameter with a thickness of 10 – 25 mm on a common axis ; the weight of the whole construction was 1 , 800 - 3 , 000 kg ) were issued to army field forces in February and March 1940 . Despite low explosion resistance ( the discs would bend after the first mine explosion ) , these mine sweeps were used successfully by the 35th tank brigade and tank battalions of the 8th Army during the Winter War .