Friday 1 June 2018

Planetary Transmission

"Attachment #2 to NKSM order #192ss
May 10th, 1941

Tactical-technical requirements for a mechanical planetary transmission for the T-34 tank
  1. The planetary transmission is to be installed into the T-34 tank to improve its mobility.
  2. The installation of a planetary transmission must not require relocation of the engine and final drives. The transmission must fit within existing dimensions of the tank and provide for convenient access to service and adjustment points.
  3. The planetary transmission must provide the T-34 with a top speed of 45-50 kph and a minimum speed of no less than 5-6 kph, as well as have a reverse gear. The transmission must allow for free changing of gears out of order, both when gearing up and gearing down.
  4. The planetary transmission must provide:
    1. Smooth turns without jerking at any gear.
    2. Turning without sudden load on the engine and excess loss of power.
    3. The ability to keep course on any surface.
    4. Brake while climbing or descending inclines up to 45 degrees.
  5. The controls must be the same as presently. The force applied to final drive clutch levers must not be more than 15-18 kg each.
  6. The planetary transmission must be highly reliable, robust, resistant to wear, and allow the tank to be controlled easily.
  7. The mechanisms of the planetary transmission must require adjustment no sooner than 50 hours of driving the tank.
  8. The warranty period of the transmission must be no less than the overall warranty period of the tank.
  9. The factory is allowed to introduce changes and additions to these tactical-technical requirements to improve the design with the permission of the NKO (GABTU)."


  1. Did they ever build one of these for a T-34? I was under the impression the Russian's like America stuck to using clutch braking until they could get the bugs worked out on more advanced types of tank steering. Plus I think it was cheaper in the short run.

    1. The T-34 stuck with clutch brakes. I can't say for sure that a prototype was never built, but it was never put into production, even though the IS had a more advanced steering mechanism.