Su-26

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 (teletanks), military engineering vehicles, self-propelled guns 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 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 the 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).

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.

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Wikipedia