By the end of 1940, when production of the T-34 started, [1][2] there were already plans to improve the vehicle’s reliability and operational capabilities by adopting more modern technology.[3]
This design project was designated T-34M.[3] It had enhanced armour protection, [1] a three-man hexagonal turret, torsion bar suspension instead of Christie suspension, road wheels with internal shock absorption, [1] increased fuel capacity, [1] and more main gun ammunition(100 rounds instead of 77 in standard T-34).[1][1][4] The bow machine gun and driver’s hatch switched positions on the glacis plate. In addition to six smaller wheels, [4] the suspension of the T-34M had four return rollers. The original model V-2 12-cylinder diesel engine developing 500 hp(373 kW) was replaced by a new 12-cylinder diesel engine which produced 600 horsepower(450 kW).[4][5] It had a new 8-speed transmission system.[4] It was the first tank design to feature transverse engine placement, which made it smaller than a standard T-34 and gave the crew more space.[4]
The Zhdanov Metallurgical Factory manufactured five sets of armour plates for the hull of the T-34M[1] and delivered them to Factory No. 183.[1] However, early in 1941 work on the T-34M ceased[1] as the production facilities were extremely busy with the mass production of the T-34.[1] When the war with Nazi Germany broke out the only sensible solution was to gradually improve the existing design.[2]
T-34-85
During the battles on the Eastern Front it became apparent that the Red Army needed a new medium tank.[4] They requested that it should have better protection at a minimal increase of weight.[4][5] In 1942 the T-43 tank design project began. It featured a new turret and shorter suspension which reduced the clearance between the roadwheels.[4] However, it concentrated on increasing armour at a time when maintaining production and increasing firepower were more important. The T-43 was cancelled, but its new turret design was adapted to carry a larger 85 mm D-5T and later ZiS-S-53 gun in a new variant called the T-34-85. It marked the end of T-34 improvements as fitting 100 mm guns in T-34-100[4] prototypes proved unfeasible.(See T-34 variants article for details).[2][6]
Prototypes[edit]
First generation[edit]
In the autumn of 1943 the design bureau of the Stalin Ural Tank Factory No. 183, located in Nizhny Tagil(in the Ural Mountains, where most of the Soviet tank industry had been evacuated after Operation Barbarossa in 1941), started working on a vehicle that would have improvement opportunities in the future, under a direct order from Joseph Stalin.[7] The intention was to retain the high mobility of the T-34 and provide it with heavier armour protection against modern tank guns. In November 1943, the chief designer, A. A. Morozov, presented the overall design of the vehicle and a model of the tank, which received the designation T-44(Ob’yekt 136). The first prototype was completed by January 1944 and two more were completed in February. The first two prototypes were armed with 85 mm D-5T guns and received the designation T-44-85, while the third prototype was armed with the 122 mm D-25-44T tank gun and received the designation T-44-122. The D-25-44T tank gun was very similar to the basic D-25 field gun, but differed in some minor details including fixed single-piece ammunition to increase the rate of fire and a double-baffle muzzle brake.[6][8] What allowed fitting such powerful armament in a medium tank weighing 30 tonnes was the construction of the hull with an innovative placement of the engine. Unlike most tanks, in the T-44 the engine was placed perpendicular to the axis of the tank. The hull was designed without sponsons. It was also much wider which made the crew compartment bigger and allowed the turret to be placed over the center part of the vehicle.[6] This reduced the overall length of the vehicle. A big disadvantage to the vehicle was that its ammo rack was on the broad left side and was easily hit, often resulting in detonation of the ammo rack, which caused a lethal explosion[citation needed]. The thickness of the armour was 75 mm on the front of the hull and 90 mm on the front of the turret. The side armour was 45 mm thick and could be reinforced by 30 mm thick additional armour plate. All three prototypes were powered by the V-2IS diesel engine which developed 500 hp(373 kW). This first generation of prototypes featured a raised cast driver’s hatch with an opening vision flap as well as mounting bolts in a ring around the base of the gun tube.[2][6][8]
Morozov’s new medium tank design received a skeptical response.[9] It was believed that putting a high-speed 12-cylinder engine with a working displacement of almost 40 liters perpendicular to the direction of travel would cause problems, including breaking the connecting rods.[9] It was believed that decreasing the displacement of the engine compartment for the purpose of enlarging the fighting compartment was unnecessary and that moving the turret rearwards would limit the elevation angle of the main gun. However, it turned out that even though rotating the engine complicated the transmission by introducing an additional reduction gear - gear-train and fan drive, it also solved many problems. The cover of the engine and transmission compartment turned along with the radiator; this allowed easier access to the engine, transmission and batteries. The significant decrease in the length of the engine compartment allowed the turret to be moved rearwards, which in turn moved its rotation axis and the center of mass[10] to the center of the hull, increased the accuracy of the main gun[6] and decreased a chance that the turret could get stuck after getting hit in the turret ring with a projectile that ricocheted.[10] The thickness of the frontal armor protection more than doubled without disturbing the center of mass or drastically increasing the weight of the tank. At the beginning of World War II the thickness of T-34 armor was considered enough. Improvements made to the T-34 during World War II included increasing the caliber of the gun(from 76.2 mm to 85 mm) and thickening the armor of the turret. No significant improvements were made to the hull. Increasing the size of the fighting compartment allowed the removal of floor ammunition stowage. The height of the tank was decreased by 300 mm, even though the turret remained almost the same. Removal of the conical pair in the transmission permitted fitting a more compact gear box and improved the control of the brakes and the steering clutch. Visibility from the driver’s position was improved. The driver was protected from being splashed b