"Overall direction of turret modernization during the war
The design of the turret was changed significantly (see fig. 143).
- In December of 1941, turrets 34.30sb-7 and 34.30sb-8 were cancelled, and turret 34.30sb-12 was introduced.
- In January of 1942, turret 34.30sb-12 was cancelled and turret 34.30sb-12-1 was introduced.
- In March of 1942, turret 34.30sb-12-1 was cancelled and turret 34.30sb-12 was introduced.
- In June of 1942, turret 34.30sb-12-12 was introduced.
This rapid change in turret likely indicated that the type of turret was unsatisfactory, and the design was only deemed satisfactory after introduction of a new turret with a commander's cupola in 1943 (see fig. 145).
In December of 1943, a turret with a 1675 mm turret ring bearing base and D-5 85 mm gun was put into production according to blueprints from the head factory.
During the production of this turret, our factory did not introduce significant changes, with the exception of altering the top of the turret and the roof to match the capabilities of the casting plant.
In January of 1944, our factory once again designed a widened turret ring turret (1600 mm) for an 85 mm ZIS-S-53 gun. The turret differed from the D-5 turret by its dimensions, size in the front, hatch locations, commander's cupola, protection, and internal layout. The amount of seats and observation devices remained the same, with the exception of the sights, which were replaced with the TSh-15 refracting sight. This sight has advantages over other types of sights in the fact that the lens is rigidly attached to the cradle carrier and the eyepiece is attached to a ball and socket joint, which allows the gunner to observe the target uninterrupted, regardless of the gun's position. (Although the eyepiece does move, but the movement is so insignificant that it has no practical bearing.)
Initially, after moving to the 85 mm ZIS-S-53 gun, the factory was forced to install D-5A guns in existing turrets due to a shortage.
In order to retain the internal equipment layout of the D-5A, the turret was rationalized. For example, the gun kept its TMFD sight, the MK-4 was used instead of the PT-4-15 periscopic sight, the gun mantlet was widened by 105 mm, but overall the equipment was left without change.
The head factory modernized the turret designed by factory #112 in July of 1944, increasing the front armour to 90 mm, and the sides to 75 mm, gradually transitioning to 52 mm. The cast gun mantlet was thickened to 90 mm in the horizontal with gradual decrease up and down. Otherwise, the turret retained its factory #112 design components.
The modernized turret with thickened walls was introduced at our factory in August of 1944 (see fig. 146).
The head factory later introduced a commander's cupola rim thickened to 75 mm from 52 mm, which was introduced by us in September of 1944.
An optical TPU-8T sight was introduced for the radio operator's machinegun in December of 1944 in order to increase precision of fire.
The 1944 mass production turret had a two piece hatch on the commander's cupola, which was difficult to open due to the weight of the pieces. In addition, the front half housed the MK-4 periscope, which made exiting through the hatch difficult. Our factory raised the issue of changing the hatch design and replacing it with a one-piece hatch, and such a hatch was introduced in March of 1945 (see fig. 147).
At the same time, new ventilation was implemented using our factory's blueprints. The layout with two extractor fans in the rear did not clean the air completely satisfactory with an 85 mm gun when hatches were closed. The change in ventilation consisted of one extractor fan installed in the front, above the gun breech, and the other was left in place, but changed to intake. As a result, the air kept moving through the fighting compartment, keeping gases away from locations occupied by the crew.
In addition, a new ammunition rack was put into production using our factory's blueprints. Instead of 12 shells, the simplified rack fit 16 shells in the turret, and its more comfortable design improved the rate of fire of the tank.
In accordance with NKTP orders, the factory designed tanks with single-use firefighting equipment, which were tested in combat.
In the future, the issue was approached in greater depth, and experiments with multiple use automatic fire extinguishers were performed.
Due to the increased weight of the modernized turret, a defect was observed where the turret ring rail was deformed. During factory trials, the turret took great strength to traverse, which led to exhaustion of the crew and reduced precision of fire.
In order to correct this, our factory introduced technical requirements and a method of hardening the turret ring rail and lower turret ring. The hardened rails were tested first on experimental vehicles, then on production vehicles, and fully proved themselves."