"To the Chief of the Red Army GABTU, Lieutenant General of the Tank Forces, comrade Ya.N. Fedorenko
December 30th, 1940
Copy: to the Chairman of the Committee of Defense of the Council of Commissars of the USSR, Marshal of the Soviet Union, comrade Voroshilov
In carrying out order #428 of the Committee of Defense issued on November 19th, 1940, I present the reasons for switching to a torsion bar suspension. The coil spring suspension of the T-34 tank is reliable, but has the following drawbacks:
- Significant oscillations make firing on the move difficult.
- The suspension spring and guide rod shafts constrict the internal space of the tank, impede free placement of components, and reduce the amount of ammunition that can be carried.
- Cutouts must be made in the sides of the tank for the suspension arms that weaken the resistance of the armour.
According to preliminary calculations, the torsion bar suspension gives:
- Increase of the fighting compartment volume by 20%.
- Reduction of the weight of the suspension by 300-400 kg.
- Increase of the fuel capacity from 465 L to 750 L, which will increase the tank's operational range by 60-100 km.
- Protection of the sides increases (where will be no cutouts).
- Installation and removal of the suspension in the field will be easier.
- The overall weight of the tank might be reduced if the layout it changed.
- The reliability of the torsion bar suspension has been proven on the KV and T-40 tanks.
- Factory #183 has a production base for the torsion bars.
The turret of the T-34 has already been widened by factory #183 by 160 mm according to protocol #848 of the People's Commissars of Defense comrade Voroshilov and Medium Machinebuilding comrade Likhachev dated March 31st, 1940. Further expansion of the turret without widening the turret ring will not result in improved firing conditions.
To increase the fighting performance of the T-34 I ask you to instruct the NKSM (factory #183) to produce two experimental tanks with a torsion bar suspension, widened turret platform, commander's cupola with all-round vision, and increased combat speed.
I ask you to approve the attached draft decree.
Authorized representative of Marshal of the Soviet Union G. Kulik"