For example, the chassis pyatikatkovuyu practically did not change, but instead of the planned introduction of the spring suspension torsion coupled with the latest in a box that allows you to shift gears while driving (PPC series of the T-34 did not have such power). Assembling the tank has changed dramatically, becoming more dense. In addition, the gunner was removed from the crew, which reduced weight and liberate space inside the crew compartment of the tank. Immediately, the thickness of armor in the front of the case has been brought up to 70 mm, the stern and sides — up to 60 mm. So Makar, these activities allowed in terms of booking closer to the languid tanks KV-1 with the lowest weight and more speed. Despite this, after the committee meeting of the Second Division NKTP February 42 th year, the project was not approved.
One of the reasons which prompted the Commissariat rid of the T-34M, were adherent to the requirements of a medium tank. The experience of fighting with German forces, which are intensively used 50 — and 75-mm anti-tank guns, again forced to reconsider the question of security of the T-34. In the spring of the same year produced the new terms of reference, which provided for the improvement of armor thickness up to 80 mm, the maximum speed — up to 50 km per hour, guaranteed mileage — up to 1500-2000 km. The increased attention paid to eliminate even the 1st significant drawback — "blindness" in the review from the commander and driver. With all of this tank should keep the power plant, trucks, rollers, other accessories and spare parts Ammunition. Task for the design of the tank, which received the designation T-43, issued IV Stalin.
As prescribed by the People's Commissariat of the tank industry was to create a three-local tower. Tank commander in the newest tower was located on the site of the stern niche, which allowed him to observe with the commander's cupola, which has radial view. Further design bureau of the plant number 183 for the base took the rejected draft T-34M, equipping it with the radio station 9P, an improved combat pack and increased fuel tanks. In July of '42 the project was approved by the board of the People's Commissariat of the tank industry, which has set November 7th term of the assembly of the first prototype.
Meanwhile, the team of designers led by A. Morozov (with the approval of the parent control) began implementation of individual components of the T-43 on the production of T-34 tanks. Namely, trying to establish the commander's cupola-type Russian T-50 or the German tanks. Finally got the three options that were different production technology (welded or cast) as the method of attachment (molded together with the roof or welded). Turret-type T-50 pretty quickly rejected because it did not have an escape and ventilation hatches, so decided to concentrate on the next working aft turrets. In general, and in this version did not work without problems — its moving backwards causing difficulties in adjusting the vertical position of the commander's seat, and place the location was not very successful. Later built a highly experienced "high-speed" version of the tank — the T-34C, which has the latest 5-speed gearbox, which is completely installed on an old place. During the test, the T-34C has developed the highest rate equal to 54.5 kilometers per hour on the highway and 15 kilometers per hour over rough terrain, with improved cross was proof of the correctness of the chosen direction of the work.
In October the 42 th to the test presented the second T-34C, filled not only a 5-speed gearbox, and a three-tower of the new standard (commander turret was shifted to the center of the tower) and 60-mm frontal armor. Although this machine has a number of advantages over the T-34, it revealed many shortcomings. The combat weight of the second T-34C was more than 32 tons and is as follows, tank had overloaded the chassis. Assembly seats crew acknowledged a failure, and mechanisms of the machine does not work reliably. But the most important thing — the T-34C no reserves for the upcoming modernization.
By September or October of '42, when the approved drawings of the T-43, many of its units have been tested for mass-produced cars and started to be implemented in the establishment. For example, since March 43 on the T-34 tank installed the latest box, and previously to the machine started to equip the commander's cupola. Work on the deep modernization of the production of the T-34 by this time had stopped and all attention is focused on T-43.
The first model of a tank made in December 1942, and he differed little from the original project. Once again, the assembly has been changed: the driver's seat was moved to starboard, he was given a supervisory hatch, "cork", the left one was installed fuel tank capacity of 500 liters. This allowed us to better protect the front part of the body, but made difficulties during evacuation . Course also installed a machine gun on the right, but now it has been fixed motionless. Aimed fire led a driver. orientation used to track bullets and corrections were introduced by divisions (risks) on the periscope.
Protection of the tank was seriously strengthened: hotel tower is 90 mm, sides — 60 mm, the front part of the case — 75 mm.
Tests of the T-43, and the layout of the second T-34C were together for three months. Tests have shown significant advantages of the new tank in terms of reliability of the machine. Polygons commission remained satisfied "third 40", but recommended to strengthen the armament of the tank, which was impossible because of the dense assembly. Makarom So, there was a project T-43 "improved" on which the planned installation of a tower with epaulets 1600 mm track lantern meshing and newest radio station. In general, do this tank the metal is not possible, as early as the summer 43rd year began to conduct active work on the installation on T-34 tanks of the massive 85-millimeter gun, which led to the emergence of T-34-85.