Here what I found about Soviet artillery tractor T-20 “Komsomolets”. That was a light mobile artillery tractor (weight 3,46 t + 0,5 t load (including 6 men in addition to 2 men crew) + 2 t trailer) with 50-52 hp engine GAZ-M, 48 km/h speed and range 152-200 km. T-20 was mainly used for tow the 37mm and 45mm AT guns and 76mm regimental gun.
Its predecessor was high-speed light artillery tractor “Pioneer” (based on “Marmon-Herrington” design and Soviet light amphibious tank T-37A chassis) with weight only 1,5 t, 1 man crew + 6 men of gun’s crew, 40 hp, 50 km/h. Near 50 “Pioneers” were built in Moscow in 1936. But they were unstable at turns, had low tractive force and were insufficiently armored. So experimental armored “Pioneer” B-1 and “Pioneer” B-2 were developed soon, but were overweight.
Much more successful was high-speed armored light artillery tractor T-20 “Komsomolets”, which was developed in 1936, using amphibious tank T-38 chassis with modified springs and truck GAZ-AA units (engineer N.Astrov). “Komsomolets” had 7-10 mm armor and 1 x 7,62mm MG (1008 shells) at the front. The engine located behind. “Komsomolets” had also 6 seats for the gun’s crew and awning with windows. There were three serial modifications of T-20 “Komsomolets”, differ in the construction of guide roller, seats, cargo platform, armament and air intake. The main defect of this quite good tractor was a low-powered car engine.
7780 T-20 “Komsomolets” were produced in 1937-1941 in Moscow, Gorky and Stalingrad. They played a great role in motorization of Soviet light artillery units (6700 T-20s were in Soviet Army in June 1941, each of infantry division should have 21 "Komsomolets"). They used very often as MG tankettes during the first period of WWII and as light tractors by partisans. The losses of “Komsomolets” were high and in September 1942 there were only 1662 T-20s in Soviet Army.
Also 101 AT self-propelled guns ZiS-30 with 57mm AT gun ZiS-2 were produced in 1941 in Gorky, using “Komsomolets” chassis and hull. ZiS-30 were the first real serial Soviet SP guns and used quite successfully against German tanks during the Battle for Moscow in 1941 by AT batteries of 20 tank brigades. But they were overweight (3,96 t) and unstable during firing because of small base and high hull of “Komsomolets” (so folding bearings were used), also they had an open hull.
Juha Hujanen wrote:
Well there was also SU-45.A Komsomoletz with 45mm gun.
May be this is a mistake, anyway I couldn't find any info about such SP gun. AFAIK experimental SU-45 with 45mm AT gun (weight 4,2 t, 3 men crew) was developed exactly by the same plant, where “Komsomolets” produced, but in 1936 (“Komsomolets” were produced in 1937-1941) and using light amphibious tank T-38 chassis and hull, not “Komsomolets”.
Also several experimental light unarmored artillery tractors were developed during WWII: LT-1 (50 hp) and LT-2 (76 hp) in Moscow; GAZ-20 “Komsomolets-2” (60 hp) and GAZ-22 (85 hp, based on T-40 chassis) in Gorky. All of them had the hull from GAZ-MM truck and could tow more heavy divisional cannons and AA guns.
The trophy “Komsomolets” were used quite active by Finns (Finnish Army had 56 T-20s in 1941 and 184 in 1943) and by Germans as light artillery tractors. Germans also developed a SP gun, using “Komsomolets” chassis and 37mm AT gun Pak 35/36. Finns used T-20s till 1961 (!). Also Romanians used 34 captured T-20s during WWII.
The photo of the Soviet light artillery tractor "Pioneer" (military parade, Moscow, 1936):
The photo of the Soviet light armored tractor T-20 "Komsomolets"
The photo of T-20 "Komsomolets" with awning, towing 45mm AT gun mod. 1932 (exercises, 1940):
http://www.battlefield.ru/tanks/komsomo ... som_07.jpg
The photo of T-20 "Komsomolets" with awning for gun's crew:
http://www.battlefield.ru/tanks/komsomo ... som_06.jpg
Photo of the Soviet light armored artillery prime mover T-20 "Komsomolets" (1937-1941, 7780 copies)
is from http://www.battlefield.ru/tanks/komsomo ... som_05.jpg
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