T-40

The T-40 amphibious scout tank was a light amphibious tank used by the Soviet Union during World War II.

Importance
Amphibious capability was important to the Red Army, as evidenced by the production of over 1,500 amphibious tanks in the 1930s. The T-40 was intended to replace the aging T-37 and T-38 tank light amphibians. It was a superior design, but due to the pressures of war the Soviets favored the production of simpler tank designs, and only a small number of T-40s were built.

Development
The T-40 was an improvement over the T-37 and T-38 in several respects. The coil-spring suspension of the T-38 was replaced by a modern torsion-bar suspension with four pairs of road wheels. The boat-shaped hull was entirely welded, in contrast to the riveted hulls of the T-37 and T-38. The welded, conical turret shape improved protection, although the armor was still very thin. Armament was a 12.7mm DShK heavy machine gun, a much more potent weapon than the 7.62mm DT machine gun mounted on the T-38.

Water propulsion was via a small propeller mounted at the rear of the hull. The propeller was set into an indent in the hull rear, and was thus better protected than the exposed propeller of the T-38. Buoyancy was provided by the large boat-shaped hull.

Production
The T-40 entered production just prior to the outbreak of war, and was intended to equip reconnaissance units. As the need for large numbers of tanks became critical, a secondary non-amphibious variant was designed on the T-40 chassis. This design became the T-60. The T-60 was simpler, cheaper, better armed, and could fulfill most of the same roles. Under the stress of war, production of the T-40 was halted in favor of the T-60. Thus only 222 T-40s were issued, compared to over 6,000 T-60s.

The last batch of T-40s built had BM-8-24 Katyusha rocket racks mounted instead of turrets. This version provided a mobile mount for a 24-rail multiple-launch rocket system, firing 82mm unguided rockets.

The T-40 was widely photographed at the time of Operation Barbarossa and also during the defence of Moscow. The type was very rarely seen after the end of 1941. Some T-40 remained in service as late 1946 in school units.