T-26 variants
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 tanks, artillery tractors, radio-controlled tanks, military engineering vehicles, self-propelled guns and armoured personnel carriers. They were developed at the Leningrad Factory of Experimental Mechanical Engineering 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" appeared only in post-war literature; these tanks were originally called "KhT", or BKhM in the documents of the 1930s. All chemical tanks based on the T-26 chassis 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,.
- KhT-26 — Flamethrower variant developed in 1933. Based on the twin-turreted T-26 mod. 1931 tank but using a single turret armed with a flamethrower, the second turret was removed.
- KhT-130 — Flamethrower variant of model 1933, using a larger 45 mm gun turret.
- KhT-133 — Flamethrower variant of model 1939.
- KhT-134 — Flamethrower variant of model 1939, with 45 mm gun.
Combat engineer vehicles
- ' — engineer tank; a bridge-laying tank based on the twin-turreted T-26 mod. 1931 chassis. According to the "System of armoured engineering armament of the Red Army", the ST-26 was developed by designers from the Academy of Military Engineering in the beginning of 1932. The ST-26 had only one shortened turret in the middle of the hull armed with a DT tank machine gun with 1,008 rounds; arc of fire was 211°. Special equipment consisted of a metal tracked bridge long and weighing, supports for the bridge and a cable winch inside the vehicle. The ST-26 was intended to provide for crossing of trenches and streams wide and barriers up to high by T-27, T-26 and BT light tanks: the bridge had a maximum load rating of. The bridge could be laid with the help of the cable winch in 25–40 seconds without crew exit; the raising operation took 2-3 min and a commander needed to come out from the vehicle in order to control the process. The ST-26 with its cable system for bridge laying was tested in the summer of 1932.
Specifications: weight - ; crew - 2 men ; speed - ; range -.
The Armoured Engineering Section of the Red Army's Research Institute of Engineer Equipment 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 and a small turret of new design. The bridge could be laid in 45 sec and the raise operation took 1.5 min. 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. 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 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 ; 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. 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.
- ' - mod. 1936 was an improved version of the ST-26. Operation of the ST-26 engineer tanks had demonstrated their low reliability, so the improved UST-26 was developed in 1936. The vehicle designers were the Red Army's Research Institute of Engineer Equipment and the Gipstalmost Factory. The UST-26 used a lever system of bridge laying with two levers and a hydraulic cylinder. The Factory No. 174 in co-operation with the Podolsk Machine Factory assembled two UST-26 in 1936. Trials performed in March 1936 showed the UST-26 was an improvement on the series-produced ST-26. Nevertheless, the UST-26 had its own disadvantages.
Remotely controlled tanks
- TT-26 — Teletank
Self-propelled guns
- SU-1 — Self-propelled gun armed with 76.2 mm regimental gun mod. 1927. The single fully armoured vehicle was built and tested in 1931.
- AT-1 — Artillery tank armed with 76.2 mm PS-3 or L-7 tank gun. Two fully armoured vehicles were built and tested in 1935, 10 AT-1 artillery tanks were planned to be built in 1936 but were cancelled.
- SU-5-1 — Self-propelled gun armed with the 76.2 mm divisional gun mod. 1902/30.
- SU-5-2 — Self-propelled gun armed with 122 mm howitzer mod. 1910/30.
- SU-5-3 — Self-propelled gun armed with 152.4 mm divisional mortar mod. 1931.
- SU-6 — Self-propelled gun armed with 76.2 mm 3K anti-aircraft gun.
- SU-T-26 — Self-propelled gun of an open-top design armed with a 37 mm gun or a 76.2 mm regimental gun mod. 1927. The Factory of Hoisting-and-Conveying Machinery named after S.M. Kirov built 14 vehicles in 1941: probably 2 with a 37 mm gun and 12 with a 76 mm gun.
Armoured transport vehicles
- TR-4 — Armoured personnel carrier
- TR-26 — Armoured personnel carrier
- TR4-1 — Ammunition transportation vehicle
- TB-26 — Ammunition transportation vehicle
- T-26Ts — Fuel transportation vehicle
- TTs-26 — Fuel transportation vehicle
Reconnaissance vehicles
- '
- '
-
Artillery tractors
- — armoured artillery tractor based on the T-26 chassis. Two unarmed variants were developed in 1932 according to the "Program of tank, tractor and armoured car armament of the RKKA": one with a canvas cover designed by the Artillery Design Office of the Bolshevik Factory and one with an armoured cabin designed by the Artillery Academy. The canvas cover had celluloid windows along the perimeter. The armoured cabin had a double-wing driver hatch in the front, two hatches on the roof and lookout hatches on the sides and rear. T-26T artillery tractors had riveted or welded hulls. The vehicle was equipped with a special towing device for towing 76.2 mm divisional guns, 122–152 mm howitzers and trailers up to weight.
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. The manufacturer was the Factory No. 174 named after K.E. Voroshilov in Leningrad. 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 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.
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
- . In early 1933, a prototype of armoured personnel carrier for mechanized units based on the T-26 chassis was manufactured according to the "Program of tank, tractor and armoured car armament of the RKKA". The TR-1 armoured personnel carrier was developed by students of the Military Academy of Mechanization and Motorization named after I. Stalin, and produced at the Leningrad Factory of Experimental Mechanical Engineering. An engine and transmission were located at the front of the vehicle, and an armoured cabin for infantrymen, equipped with a rear door and six portholes in side walls, was located in the rear. The TR-1 was an unarmed vehicle. In August–October 1933 this armoured personnel carrier has passed extensive tests at Kubinka proving ground.
Series production
Around 1,701 armoured combat vehicles based on the T-26 chassis were produced in the USSR from 1932 till 1941.| 1932 | 1933 | 1934 | 1935 | 1936 | 1937 | 1938 | 1939 | 1940 | 1941 | Total | |
| KhT-26 | 91 | 106 | 430 | 7 | - | - | - | - | - | - | 552 |
| KhT-130 | - | - | - | - | 10 | - | 290 | 101 | - | - | 401 |
| KhT-133 | - | - | - | - | - | - | - | 42 | 265 | - | 269 |
| KhT-134 | - | - | - | - | - | - | - | - | 2 | - | 2 |
| ST-26 | 3 | - | 44 | 20 | 2 | 1 | - | 1 | - | - | 71 |
| TT-26 and TU-263 | - | 33 | - | - | 74 | - | 55 | - | - | - | 162 |
| SU-5 | - | - | - | 34 | 30 | - | - | - | - | - | 33 |
| T-26T | - | 183 | - | - | 14 | - | - | - | - | - | 197 |
| SU-26 | - | - | - | - | - | - | - | - | - | 145 | 14 |
- 1Delivered to customer in 1933
- 2Prototypes
- 3Teletanks and control tanks of all types
- 4Prototypes of SU-5-1, SU-5-2, SU-5-3
- 5Produced in Leningrad at the "Factory of Carrying-and-conveying Machines named after S. Kirov"
Vehicle-mounted engineer equipment
- Tank mine sweeps. Several mine sweeps of different designs for the T-26 and ST-26 tanks were developed in the USSR, but none of them were passed into army service. Three models of mine plows were tested in 1932–1934. Trials showed very poor performance of such types of mine-sweep on compacted soil or scrubby land. The much more successful KMT-26 mine roller was developed and tested in July 1934; three such mine-exploding rollers were produced. An experimental mine flail was tested in August–September 1939 also. Mine sweeps could be mounted on T-26 or ST-26 tanks in 1.5 hours and jettisoned without crew exit if necessary.
- Fascines. Three types of remotely released large fascines for trench crossing were developed for the T-26 and the ST-26 in 1937–1939. These fascines made possible the crossing of trenches and antitank ditches 3.5 m wide and 1.2 m deep. Only ten sets of wooden fascines were produced. The fascines somewhat restricted the field of fire of the main gun.
- Wire cutters. Factory No. 174 developed special wire cutters for T-26 tanks in 1940. The automatically operated TN-3 tank wire cutters were intended for breaching enemy wire obstacles. They were located on the rear of the vehicle over the tank tracks, cutting off wire caught in the tracks. Trials performed in October 1940 in Kubinka proving ground demonstrated that the design needed improvement.
- Snowplow. The ST-26 engineer tank with a mounted snowplow from the Ya-5 truck was tested in Kubinka proving ground in 1933. In 1935 a special tank snowplow for the ST-26 was developed for clearing roads of 3 m width, in snow up to 1.2 m deep. The snowplow could be mounted on the ST-26 in 15 min. It was officially passed into army service but follow-up trials indicated that it could not clear even 0.6-0.8 m deep snow.
- Other equipment. Between 1934 and 1940 the following equipment for the T-26 tank was developed and tested: brushwood mats and wooden planks for swamp crossing, special water/bog tracks, automatic coupling equipment for two tanks intended for crossing trenches of 3.8-4.2 m width, an implement for destroying antitank teeth and road-blocks, a magnetic mine detector, different track grousers.