By the end of July, the tank divisions were effectively gone. The ones that remained in name at the front, had the real strength of brigades or less. Several armies formed "Tank Groups" in August and September 1941. Basically, these were collections of what tank and motorized forces were left in the army, under the highest-ranking armor officer available. What little information is available on these groups (they only lasted a few weeks, at best) indicates they operated at battalion or small regiment strength.
From the first days of the war, some tank units had been split into tank battalions for direct support. As divisional headquarters ceased to function, many separate tank battalions appeared in the Soviet Army in August and September 1941. Some of these were formed from dissolving tank divisions and tank regiments. Some were formed as 'ad hoc' units, using tanks repaired in local factories and whatever crews could be found. Some of these battalions, in fact, had no numerical designation for some time. Eventually, most of the separate tank battalions would be used to form larger units: separate tank regiments or tank brigades.
In late August 1941, the Soviet army began forming tank brigades. The advantages of the tank brigade were:
1. It was a unit small enough that the Soviet tank officers could handle it.
2. They could be formed fast -many were put together from existing tank battalions or tank regiments in just a few weeks.
3. Enough of them could be formed that everybody could have some tank support, even if not very much.
4. Although small, the tank brigade could still provide some minimum support for the tanks, in the form of infantry and light artillery and antiaircraft units.
The major disadvantage of the tank brigade was that it did not last long in combat. An individual tank brigade could lose all of its tanks in just a few days of intense combat. Later in the war, when the tank and mechanized corps controlling the tank brigades had their own repair bases, spare tanks, and even reserve tank crews, tank brigades could survive and sustain combat for some time. In 1941, individual tank brigades operating under army HQ with no repair units and few supporting units quickly disintegrated. The average combat strength of a tank brigade in the Battle of Moscow in December, for instance, was about 12 tanks - smaller than a prewar tank company!