Even as the classic T-34 Medium Tank helped to turn the tide of the War in the East for the Soviets, there were several developments on the part of the Germans that became cause for concern for Soviet warplanners. In May of 1942, the Germans began using the 75mm KwK 40 L/48 anti-tank guns against the T-34 at-range with consistent success so this drove a new Soviet tank project hoping to succeed both the T-34 Medium Tank and KV-1 Heavy Tank lines by combining the best qualities of both - speed/mobility of the former and armor protection of the latter.
The approach was known as a "Universal Tank" and essentially laid the groundwork for what was to become the "Main Battle Tank" of the Cold War period (1947-1991). Soviet authorities commissioned engineers at the Nishni Tagil and Chelyabinsk production facilities to begin work on this new Universal Tank to have a single design take the place of two or more types in service and help to end the German armored scourge once and for all. The Nishni Tagil plant - Factory No.183 (Ural Waggon Works) - took the lead on the project as the workers at Chelyabinsk were deep into the KW-13 program (detailed elsewhere on this site).
The design would be heavily influenced by the in-service T-34 and carried over its stout, angled hull facings while mating this to an all-new, more spacious three-man turret containing the main armament. The gun of choice became the same 76.2mm F-34 weapon of the T-34, which was a proven commodity in-the-field against German armor, and this was set in the frontal face of the turret. The radioman and his machine gun position at the bow were deleted so as to slide the driver's position more centerline, though slightly offset to the starboard side of the forward hull. The new turret featured greater armor protection than that of the T-34 and also housed a 7.62mm DT machine gun in a coaxial fitting as an anti-infantry measure. Armor protection of the new tank reached between 16mm and 90mm along the various facings, more so at the critical front and side facings of the hull (70mm) and turret (90mm) which inevitably saw more direct action from the enemy. A commander's cupola was seated at the left-hand side of the turret roof line. Inside there was a crew of four - driver, tank commander, gunner, and loader.
The running gear involved five large road wheels to a hull side and no track-return rollers were used. Unlike the T-34's American Christie-based suspension system, the T-43 was given a more modern torsion bar arrangement to improve cross-country mobility while reducing complexity. Drive power was from a 500 horsepower V-2-34 12-cylinder diesel-fueled unit providing for a road speed of 48kmh out to a range of 300 kilometers. The vehicle could ford a water depth of up to 1.3 meters.
The end product yielded a running length of 8 meters with a beam of 3 meters and a height of 2.58 meters. Weight reached 34 tonnes. Up to 70% of the existing parts of the T-34 (Model 1943) were used in making up the T-43.
Evaluations were quick to note the T-43's susceptibility to the German 88mm FlaK guns being used in greater numbers in the Anti-Tank (AT) role (as well as being used as the primary armament of the Tiger I Heavy Tanks). In fact, armor protection and mobility of the T-43 was found to be no better than that already showcased by the T-34 which was a cause for concern. Additionally, the weight of the added armor and new turret drove down road speeds and hampered mobility of the tank, particularly during cross-country affairs. The shift to an all-new turret would also disrupt production at many of the important Soviet facilities should the T-43 project have matured towards serial manufacture.
Add to this the fact that, during the Battle of Kursk (July 5th, 1943 - August 23rd, 1943) - Germany's final "blitzkrieg" which once-again starred the T-34 - after-action reports suggested that the existing T-34 merely lacked a more potent main gun. In response to this, T-43 engineers attempted to mate a more powerful 85mm D-5T main gun into a modified version of the new T-43 turret but this endeavor did not help the T-43 project success. It became much more convenient to simply up-gun the existing T-34 - and this went on to produce the famous T-34/85 Medium Tank (detailed elsewhere on this site) design. Because of this, the T-43 program was therefore cancelled in full with nothing more than a single prototype realized.
For the Germans, who suspected a T-34 successor to be in the works under the designation of "T-43", the T-34/85, when it entered service in 1944 as the standard combat tank of the Soviet Army - was mistakenly thought to be the new T-43 and thus German wartime reports made frequent mentions of a "T-43" in direct combat service in numbers along the East Front.