T-40

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. The vehicle's armament consisted of a single 12.7 mm DShK heavy machine gun, which was a much more potent weapon than the 7.62 mm DT machine gun mounted on the T-37 and the T-38.

Water propulsion was achieved 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.

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 were produced with BM-8-24 Katyusha rocket racks mounted instead of a turret. This version provided a mobile mount for a 24-rail multiple-launch rocket system, firing 82 mm unguided rockets. 
A total of 44 T-40s were converted into this model in autumn 1941.

There was also the T30A and the T30B light tanks, which were the prototypes of the T-40 and T-60 respectively. Both of them were armed with a 20 mm cannon with a DT machine gun. These prototypes were preserved in the Kubinka Tank Museum.

The T-40 was widely photographed at the time of Operation Barbarossa and also during the defence of Moscow. Many were knocked out during the fighting. The type was very rarely seen after the end of 1941, although some T-40s remained in service as late 1946 in some school units.

T-40 amphibious scout tank
A T-40 in the Kubinka Tank Museum.
Type	Amphibious light tank
Place of origin	Soviet Union
Service history
In service	1941–46
Used by	Soviet Union
Wars	World War II
Production history
Produced	1940–41
Number built	222
Variants	BM-8-24 Katyusha, T-30 light tank
Specifications ([1][2][3])
Weight	5.9 t (6.5 short tons)
Length	4.10 m (13.5 ft)
Width	2.33 m (7.6 ft)
Height	1.90 m (6.2 ft)
Crew	2
Armour	4–13 mm (0.16–0.51 in)
Main armament	12.7 mm (0.50 in) DShK machine gun
Secondary armament	7.62 mm (0.300 in) DT machine gun
Engine	GAZ-202 85 hp (63 kW)
Power/weight	12 hp/tonne
Suspension	torsion bar
Operational range	450 km (280 mi)
Speed	45 km/h (28 mph)