Wednesday 10 April 2019

Torsion Bars for the T-34

"December 30th, 1940
To the Chair of the Committee of Defense of the Council of Commissars, Marshall of the Soviet Union, comrade Voroshilov

In carrying out the Committee of Defense decree #428 issued on November 19th, 1940, I present to you my thoughts on moving the T-34 to a torsion bar suspension.

The coil spring suspension currently used on the T-34 is reliable in its function, but has the following drawbacks:
  1. There is significant longitudinal oscillation, which makes accurate fire on the move difficult.
  2. The shafts containing the springs take up a lot of space inside the tank, which makes it hard to position components and reduces the ammunition capacity.
  3. The side plates have to be cut to allow for vertical movement of the suspension arms, which reduces protection.
According to preliminary calculations, the torsion bar suspension will give us:
  1. 20% increase in volume of the fighting compartment.
  2. Reduction in weight of the suspension of 300-400 kg.
  3. Increase of fuel capacity from 465 L to 750 L, which will increase the tank's range by 60-100 km.
  4. More resilient side armour (cuts will not have to be made).
  5. Removal and installation of suspension elements in field conditions is made easier.
  6. Reliability of the torsion bar suspension is proven by T-40 and KV tanks.
  7. Factory #183 can produce torsion bars.
The turret has already been widened by factory #183 according to decree #848 issued by the People's Commissar of Defense comrade Voroshilov and People's Commissar of Medium Manufacturing comrade Likhachev by 160 mm, and widening the turret further without widening the turret ring will not give improved conditions for aimed fire.

To improve the fighting qualities of the T-34, I ask the NKSM (factory #183) to develop two experimental tanks with torsion bar suspensions, wider turret ring, a commander's cupola, and higher top speed by April 1st, 1941. The draft of the proposed decree is attached, and I ask for your approval.

Authorized representative of Marshall of the Soviet Union, Kulik"


  1. While I prefer torsion bars I do feel that the two spaced plates of steel holding the Christie style suspension did provide a degree of protection against shaped charge warheads.

  2. From one hand coil springs of Christie suspension took significal space of hull, but from other hand, in my opinion springs don't reduce crew comfort. Springs was located front of and rear of tankers. In terms of fighting compartment, springs don't interference with turret ring (in T-34-85 interferenced, but only below level which was created by covers of ammo boxes). In terms of ammo capacity- T-34 have floor mounted main ammo rack. In my opinion T-34 with torsion bars don't have far more ammo (torsion bars also took space near hull floor). In terms of fuel tanks- yes, T-34 with torsion bars can have far bigger fuel tank capacity (Christie springs took space near side armour of hull, and in this same space was located fuel tanks), but from other hand, also typical T-34 have pretty big cruising range.

    Below my "collage", which show that in T-34-85, coil springs of Christie suspension interference with turret ring "light" only below crew-used part of battle compartment.