Plans for an up-gunned T-64A with a more powerful 125-mm gun had already been made in 1963. Production of the T-64 with a 115-mm gun began in 1964.
This led to the introduction of the 700 hp 5TDF engine, which was unreliable, difficult to repair, and had a guaranteed lifespan similar to World War II designs. The much smaller design presented a problem when selecting a suitable engine. To do this, the crew was reduced to three soldiers, removing the loader by introducing an automated loading system. Under the direction of Alexander Morozov in Kharkiv a new design emerged with the hull reduced to the minimum size possible. The T-64 (Object 432) was a very ambitious project to build a competitive well-armoured tank with a weight of not more than 36 tons. The development of the T-72 was a direct result of the introduction of the T-64 tank.
