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IS-6 heavy tank

The IS-6 was a Soviet heavy tank built as a breakthrough tank. The first prototype, the Object 253, overheated too much and required too much copper therefor cancelled. The second prototype was lighter weight and had more speed. The tank was not much of an improvement of the IS-4.

The IS-6 heavy tank project (object 253) was developed at the beginning of 1944 at Plant No. 100. The tank was armed with a 122 mm D-30 gun, identical in ballistics and ammunition to the D-25T. The cannon was paired with a 7.62 mm SGMT machine gun, and a 12.7 mm DShK machine gun was mounted on the turret roof on the turret.

In parallel, another prototype IS-6 tank (object 252) was manufactured and tested, on which a mechanical transmission was used. In addition, in the chassis were used rollers of increased diameter, supporting rollers were not. The maximum speed of about 252 was 43 km / h, as the eighth gear in the gearbox was blocked. The weight of the tank is 51.5 tons.

In terms of firepower, the IS-6 tank did not exceed the IS-2, IS-3, and IS-4. Its armor protection was better than the IS-2 and IS-3, but somewhat inferior to the IS-4. The installation of an electric transmission facilitated control and was supposed to enhance its maneuverability. However, this did not happen due to the large mass of both the machine itself and the electric transmission, as well as due to the low reliability of the latter. As for the version of the IS-6 with a mechanical transmission, with the exception of armor protection, it generally had no advantages over other heavy tanks.

The IS-6 heavy tank project (Object 253) was developed at the pilot plant No. 100 in Chelyabinsk in the first half of 1944. The main feature of this combat vehicle was the use of an electromechanical transmission on it. In accordance with the decision of the GKO, by order of the People's Commissar of the Tank Industry of June 8, 1944, Uralmashzavod, together with plant No. 100, was entrusted with the production of drawings and the production of prototype IS-6.

The main design work had already been completed by Plant No. 100, a significant part of which also fell to the designers of Uralmash, since the production of working drawings was made here. Prototypes were manufactured by both plants with assembly and debugging of vehicles at Uralmashzavod. In the autumn of 1944, after factory tests, the IS-6, together with a second set of parts and a spare hull, was sent to Kubinka for comparative tests of new heavy tanks made by tank factories.

IS-6 had a classic layout with the shape of the hull and turret, close to the tank IS-4. The 122 mm D-30 cannon was paired with the Goryunov machine gun. On the roof of the tower on the turrets installed anti-aircraft machine gun DShK. The tank’s ammunition consisted of 30 rounds of separate loading, 1,200 rounds of 7.62 mm and 500 rounds of 12.7 mm caliber anti-aircraft machine gun. TBSh sight - telescopic, tank. The anti-aircraft machine gun was equipped with a K8-T collimator sight. At the disposal of the commander, driver, gunner and loader there was one sighting device MK-4.

750-liter B-12V engine from. housed in the aft. The electromechanical transmission included the main generator DK-305A with a capacity of 385 kW and a mass of 1740 kg, installed together with the engine. In one unit with the main generator on a common shaft was a three-phase synchronous generator SG-1A, designed to power the fan motors of the traction engine and diesel cooling system, as well as to drive the battery charging unit.

Two small G-73 direct current generators were mounted on the diesel engine, which fed the excitation circuits of the DK-305A and SG-1A generators. Traction electric motors DK-302A and DK-302B of reverse action through final drives connected to the drive wheels of the tank. Traction was adjusted by changing the excitation of the main generator. The operating current reached 960 A, when driving on the highway it was 490 A, on the terrain - 740 A. The voltage in the circuit reached 500 V. The chassis of the IS-6 tank with six track rollers and three support rollers on board was similar to the chassis of the IS-2 .

Individual suspension, torsion bar. A 10-P radio station and an intercom TPU-4bis F. were installed on the tank. Another model of the IS-6 ( object 252 ) was manufactured with a mechanical transmission of the IS-3 type. Apparently, a second set of parts and a spare armored hull were used for its manufacture. Large-diameter track rollers were used in the chassis, and support rollers were missing. The maximum speed was 43 km / h (the eighth gear in the gearbox was blocked) The mass of the tank decreased to 51.5 tons.

The State Commission appreciated the use of electric transmissions on the IS-6, which made it easier to control the machine, however, the identified shortcomings reduced this advantage to zero. The mass of the transmission was too large, which affected the total combat mass of the tank and, as a consequence, its mobility. In addition, the IS-6 did not stand out from the serial IS-2 in terms of armament, and in armor protection it was similar to the IS-3 and IS-4, which were preparing for serial production. As a result, it was decided to stop work on the IS-6 and after the war both prototypes were scrapped.