In 1935, a new modification of the BT tanks, which received the BT-7 index, was put into service and put into mass production. The tank was produced until 1940 and was replaced in production by the T-34 tank. (Also read “Medium Tank T-44”) Compared to the BT-5 tank, its hull configuration has been changed, armor protection has been improved, and a more reliable engine has been installed. Part of the connections of the armor plates of the hull has already been carried out by welding.
The following variants of the tank were produced:
- BT-7 - a linear tank without a radio station; since 1937 it was produced with a conical turret;
- BT-7RT - command tank with radio station 71-TK-1 or 71-TK-Z; since 1938 it was produced with a conical turret;
- BT-7A - artillery tank; armament: 76,2 mm KT-28 tank gun and 3 DT machine guns;
- BT-7M - a tank with a V-2 diesel engine.
In total, more than 5700 BT-7 tanks were produced. They were used during the liberation campaign in Western Ukraine and Belarus, during the war with Finland and in the Great Patriotic War.
Tank BT-7.
Creation and modernization
In 1935, KhPZ began production of the next modification of the tank, the BT-7. This modification has improved cross-country ability, increased reliability and facilitated operating conditions. In addition, the BT-7 featured thicker armor.
The BT-7 tanks had a redesigned hull, with a large internal volume, and thicker armor. Welding was widely used to connect armor plates. The tank was equipped with an M-17 engine of limited power and with a modified ignition system. The capacity of the fuel tanks has been increased. BT-7 had a new main clutch and gearbox, developed by A. Morozov. The side clutches used variable floating brakes designed by Professor V. Zaslavsky. For the merits of KhPZ in the field of tank building in 1935, the plant was awarded the Order of Lenin.
On the BT-7 of the first issues, as well as on the BT-5, cylindrical towers were installed. But already in 1937, cylindrical towers gave way to conical all-welded ones, characterized by a greater effective armor thickness. In 1938, the tanks received new telescopic sights with a stabilized line of sight. In addition, tanks began to use split-link tracks with a reduced pitch, which showed themselves better during fast driving. The use of new tracks required a change in the design of the drive wheels.
Some radio-equipped BT-7s (with a cylindrical turret) were equipped with a handrail antenna, but BT-7s with a conical turret received a new whip antenna.
In 1938, some line tanks (without radios) received an additional DT machine gun located in the turret niche. At the same time, the ammunition had to be somewhat reduced. Some tanks were equipped with a P-40 anti-aircraft machine gun, as well as a pair of powerful searchlights (like the BT-5) located above the gun and serving to illuminate the target. However, in practice, such floodlights were not used, since it turned out that they were not easy to maintain and operate. The tankers called the BT-7 "Betka" or "Betushka".
The last serial model of the BT tank was the BT-7M.
The experience of fighting in Spain (in which the BT-5 tanks participated) showed the need to have a more advanced tank in service, and in the spring of 1938, ABTU began to develop a successor to the BT - a high-speed wheeled-tracked tank with similar weapons, but better protected and more fireproof. As a result, the A-20 prototype appeared, and then the A-30 (despite the fact that the military was against this machine). However, these machines were more likely not a continuation of the BT line, but the beginning of the T-34 line.
In parallel with the production and modernization of BT tanks, KhPZ began to create a powerful tank diesel engine, which in the future was supposed to replace the unreliable, capricious and fire hazardous carburetor engine M-5 (M-17). Back in 1931-1932, the NAMI / NATI design bureau in Moscow, headed by Professor A.K. Dyachkov, developed a project for a D-300 diesel engine (12-cylinder, V-shaped, 300 hp), specially designed for installation on tanks ... However, it was only in 1935 that the first prototype of this diesel engine was built at the Kirov Plant in Leningrad. It was installed on BT-5 and tested. The results were disappointing as the diesel power was clearly insufficient.
At KhPZ, the 400th department headed by K. Cheplan was engaged in the design of tank diesel engines. The 400th department collaborated with the department of engines VAMM and TsIAM (Central Institute of Aviation Engines). In 1933, the BD-2 diesel engine appeared (12-cylinder, V-shaped, developing 400 hp at 1700 rpm, fuel consumption 180-190 g / hp / h). In November 1935, the diesel engine was installed on the BT-5 and tested.
In March 1936, the diesel tank was demonstrated to the highest party, government and military officials. BD-2 required further refinement. Despite this, it was already put into service in 1937, under the name B-2. At this time, there was a reorganization of the 400th department, which ended in the appearance in January 1939 of the Kharkov Diesel Building Plant (HDZ), also known as Plant No. 75. It was the KhDZ that became the main manufacturer of V-2 diesels.
From 1935 to 1940, 5328 BT-7 tanks of all modifications (excluding BT-7A) were produced. They were in service with the armored and mechanized troops of the Red Army for almost the entire war.
