Was designed for infantry support and was based on the (8) 15 British 6-Ton Vickers Type Es that were imported. One was tested at the F. E. Dzerchinskiy Academy of Artillery Weapons in Leningrad.
The Directorate of the Mechanization of the Red Army (UMM), led by I. A. Khalepsky, purchased a Vickers-Armstrong 6 ton E Light Tank. It arrived in 1930.
A license to build the tanks was obtained from Vickers-Armstrong Ltd. and prototypes were being manufactured at the Bolshevik factory in Leningrad. The Experimental Design department ( OKMO) headed up the design, under the leadership of N. V. Barikov and S. A. Ginzbury. The test vehicles were designated TMM-1 and TMM-2 and were very similar to the 6-Ton Vickers.
The Revolutionary War Department gave orders on February 13, 1931, to produce the T-26 even though development and testing hadn't concluded yet. These were to replace the obsolete MS-1 models. An engineer, Zigelya, made some minor modifications and production started.
Production of the T-26A series was ended and the T-26B series became the main one produced. The T-26B series was to be used by the calvary.
Based on the performance in the Spanish Civil War improvements were made (T-26-S). These involved fitting shot deflecting conical turrets, welded armor, and some had rolled mantlets for the turret.
The military wanted the 2 turrets improved so that they could be fired over a wider arc. Larger visors were added, the MGs were ball mounted, and the turning circles were limited to 265 degrees.
The commander was in the left turret in the dual turreted models. The seats in the turrets were fixed in place and didn't turn with the turrets.
The driver sat on the right, next to the multistep mechanical gearbox.
The engine was based on the British Armstrong-Siddeley (renamed GAZ) which produced 91 HP. There was a firewall between it and the fighting compartment.
Tanks produced from 1931-1933 had their armor riveted on.