SMK Experimental Heavy Tank
In 1937 the Design Bureau of the KhPZ received the tasking to design a new heavy breakthrough tank on the base of the T-35. A requirements document of the ABTU, affirmed on 5 November 1937, suggested that a three-turreted vehicle be created, with a weight of 50-60 tons, armor thickness of 45-75mm, and armaments consisting of a single 76mm and two 45mm guns, and two DK and six DT machine-guns.
It was planned to use the transmission and drive train of the T-35 in the new tank. However, the Design Bureau KhPZ, which in normal circumstances lacked sufficient resources to carry out such complex work, had been subjected to mild repressions among its engineering staff working on the project. Therefore, despite countless demands of the ABTU, by the beginning of 1938 the KhPZ designers had managed only to complete preliminary designs of the six variants of the new tank, which differed only in the arrangement of the armaments. Therefore, in April 1938, in order to accelerate the design of the new heavy breakthrough tank, the ABTU brought into the effort the LKZ, with its powerful production base and the experience of serial production of the T-28, and also Kirov Factory #85, the cadre of which had experience in their own right in the development of new types of combat vehicles. The former plant (LKZ) designed the SMK (Sergey Mironovich Kirov) tank, under the leadership of engineer A. S. Ermolaev. Factory #85 designed "Project 100," which subsequently received the designation T-100, led by engineer E. Sh. Paley. Thus, contrary to some oral and written accounts, the SMK and T-100 tanks had different bases and were developed simultaneously.