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IS-4 Heavy Tank

In 1946, the Soviet Army received the new heavy tank IS-4, the development of which, like the tank IS-3, began in the years of the Great Patriotic War. This combat vehicle was created in accordance with the IT assigned to the new heavy tank in the last years of the war, and, in contrast to the IS-3, was not a modernization of the IS-2 tank. The new tank was developed as an offensive weapon for breaking through the prepared defenses of the enemy and was intended to destroy manpower, enemy fire weapons, and also to fight with its heavy tanks and artillery.

Tank IS-4 was produced at ChKZ in 1947-1949. and during the time of mass production, it was upgraded with a change of mark on the IS-4M. The plant manufactured a small batch of IS-4M tanks in 1951. In the same year, according to the revised technical documentation, the ChKZ carried out the modernization of all previously produced vehicles.

The development of the IS-4 heavy tank began in 1944, somewhat earlier than the IS-3. The initiators of the creation of the new machine were the leaders of the ChKZ: I.M. Zaltsman (director), S.N. Makhonin (chief engineer) and N. L. Dukhov (chief designer); Lead Designer of the project - L.S.Troyanov. Their main task was to create a promising heavy tank for the final stage of the war and for the subsequent time. It should be noted that this work, as in the case of EC-3, was carried out with a certain degree of conspiracy. Neither the People's Commissar of the Tank Industry V.V. Malyshev, nor the First Secretary of the Chelyabinsk Regional Committee of the CPSU (B.) N.S. Patolichev were informed about it until the time. The design was funded from the factory budget. Apparently, such secrecy was caused by the fact that the conceived machine initially did not fit into the 46-ton weight limit, approved by JV Stalin, and the plant management did not want to “tease the geese” before the time.

The IS-4 serial model was preceded by products 701-2, 701-5 and 701-6. These machines differed from each other in thickness of armor, brand and caliber of the gun, location of crew members. On the product 701-2, a C-34 100-mm gun was installed with an initial velocity of an armor-piercing projectile of 600 m / s. Ammunition consisted of 30 shots. There were a telescopic sight TSH-17 and viewing devices MK-4. The thickness of the frontal and side plates of the turret and the hull was the same and did not exceed 160 mm. 750 hp twelve-cylinder diesel engine B-12 allowed the 55.9-ton combat vehicle to reach a speed of 43 km / h. The crew consisted of 4 people. On object 701-5, a 122 mm D-25T cannon was installed and the thickness of the turret armor increased. The mass of the tank increased to 58.5 tons.

Object 701 -6 received the military designation of the IS-4 and in 1947 was adopted by the Soviet Army. The body was welded from large thickness armor plates, and the cast turret had a variable wall thickness with developed zygomatic and frontal details. Frontal and side armor of the hull and turret were not penetrated by foreign anti-tank guns with a range of 1000 m, and the stern sheet of the hull had the same thickness as the front of the turret of the IS-2 tank.

The driver was located in front of the axis of the car. Above his seat there was a small round hatch. closed by moving aside a cover. In the manhole cover were installed two viewing devices, which it was necessary to remove before opening the hatch. The driver's seat was height adjustable and could be installed in the firing position with the hatch closed and in the stowed position with the hatch open.

The front of the tank turret was covered with a removable armor plate fastened with bolts. The hatch closed by this sheet was intended for mounting and dismounting the gun. In the rear part of the turret’s roof they were located on the left - the hatch of the tank commander with a lid, on the right - the loader hatch with the lid. In the covers of the hatches and the left part of the roof were viewing devices, and in the cover of the commander's hatch there was a periscope viewing device TPK-1.

The rotation of the turret was carried out by the rotation mechanism, which had two drives: manual and electric. The planetary block of the turning mechanism allowed separate and joint operation of these drives without any switching.

Gun D-25T caliber 122 mm was paired with a 12.7-mm machine gun DShK. On the head of the tank was placed on the anti-aircraft turret of the second machine gun DShK, equipped with a K8-T collimator sight.

For aiming the gun and coaxial machine gun used the mechanism of rotation of the turret, sector lifting mechanism and commander control system with electric drive. The guns were fired at direct fire using the TS-45 telescopic articulated sight, and from closed positions with the help of a lateral level and a goniometric circle on a turret chase.

Ammunition consisted of 30 shots of separate loading. The peculiarity of the IS-4 ammunition was the placement of projectiles in special metal cassettes. Each cassette consisted of a cylinder, a damping spring, and a spring lock. An additional cup was inserted in the armor-piercing projectile cartridges (between the shock-absorbing spring and the projectile head), and in the high-explosive fragmentation cassettes a fuse cap for the head fuse. For armor-piercing projectiles, there were 12 cassettes, for high-explosive fragmentation grenades - 18. The holders of the armor-piercing projectile locks were painted red, and high-explosive fragmentation grenades - in yellow.

Ammunition 12.7-mm cartridges consisted of two stacks of 500 pieces each. In one package, cartridges were loaded into ribbons of 50 pieces each and placed in box-stores, two of which were on machine guns. In the second piling, cartridges in packs of original packaging were stored in four canvas bags.

The tank was equipped with a 12-cylinder, four-stroke, V-shaped uncompressed diesel V-12 liquid cooling with a working volume of 38,800 cm3 and a maximum power of 750 hp. (552 kW) at 2100 rpm It differed from its predecessors of the 8-2 family mainly by the presence of a centrifugal non-switching-off supercharger. The fuel system included three main built-in fuel tanks with a total capacity of 410 liters. Four additional fuel tanks of 90 liters each were installed outside the tank aft. Instead of the fuel pump NK-10 (as in B-2), a twelve-plunger pump NK-12 was used.

In addition, changes were made to the B-12 engine regarding the design of the crankcase, cylinder heads, injectors, camshaft, exhaust valves, oil filter and water pump. Two axial horizontal fans provided cooling radiators. Starting the engine in the cold season was facilitated by heating the intake air. Air cleaners - type-Multiclone, two-stage, with a bunker for collecting dust.

Power transmission (more precisely, the mechanism of gears and turns) - planetary, providing six gears forward, three back and two neutral positions. It consisted of a three-speed gearbox, which was a two-row planetary gear with three friction elements and served as a gearbox, a conical reverse and a gearbox type ZK with multipliers. The turning mechanism of the type ZK was developed in 1935–1936 by professors MK Kristi and GI Zaychik and was made in metal for a light amphibious tank T-38, however, due to its complicated construction for that time, it was not used.

Its main advantages were: automatic increase in torque on the drive wheels when turning compared to the straight-line movement; steady rectilinear motion; creation of braking force without brakes. The main drawback of the ZK type turning mechanism was a significant drop in the center of gravity of the vehicle when turning, which led to a deterioration in the dynamics when exiting the turn due to engine overload and a decrease in the rotational speed.

The ZK-type turning mechanism showed good results in tanks with low power density (11–13 hp / t), since it reduced the power required for turning. With the increase in power density, its use became inexpedient.

This is one example where a progressive design solution outpaced the technology that existed at the time. But the use of friction discs of friction elements working in oil, which were not mastered by domestic industry, could increase the reliability of the transmission and reduce its weight and size. The drive for controlling the gears and turns mechanism was mechanical, selector, with hydraulic pedal setting on the forward gears.

The drive wheels had removable rims with 14 teeth. Guide wheels with screw tensioning mechanisms located in front. On each side there were 7 support and 3 supporting skating rinks. Suspension - individual, torsion. The caterpillar is small-scale. helical gear, with open hinge. The number of tracks in each track is 86. Track pitch is 160 mm, width is 720 mm.

The electrical equipment included four rechargeable batteries connected in parallel-series, with a total capacity of 256 Ah, the G-73 generator with a power of 1500 W, the electric starter CT-700 with a power of 15 hp. The wiring system is single-wire, with a voltage of 24V. For emergency lighting devices, a two-wire wiring system was provided. The machine was installed automatic fire-fighting equipment with thermoelectric switches in the engine and transmission compartments. Communications equipment consisted of radio station 10-RK-26 and intercom TPU-4bisp.

It is officially considered that the mass production of the IS-4 began in 1947. However, a number of facts suggest that some of the cars were released earlier - in 1946 and even in 1945. Unlike the latter, modernized machine guns DShKM 1938/46, a collimator sight K10-T and radio station UURT were installed on tanks produced in 1947-1948. Since 1948, the tanks were equipped with intercoms TPU-47.

In total, during serial production until 1949, about 250 IS-4s were manufactured. The cost of one car was 994 thousand rubles.

These tanks were directed mainly about military units stationed in the Far East - in Transbaikalia. Primorye, etc. The service of the new tank was short-lived - the IS-4 was decommissioned and put into long-term storage, and then removed from service. The reason for this was a variety of circumstances. This combat vehicle, which had the most powerful booking in the world at the time of its creation, had significant shortcomings: a mass exceeding the carrying capacity of most of the existing bridges and vehicles at that time, low transmission reliability, low traffic throughput due to high specific pressure (0.9 kg / smg). The maneuverability of the tank was also insufficient, and the armament of the IS-4 had no advantages over the heavy tanks IS-2 and IS-3.

In a complete state, the IS-4 tank can be seen only in two places: in the Kubinka town near Moscow and at the exposition of the Museum of armored weapons and equipment and as a monument in the village of Zabaykalsk, Chita Region.