FM 100-2-2 gives details of Soviet river crossings
and has this to say
Tank unit crossings are more complicated than motorized rifle assaults. Although tanks may be attached to support motorized rifle assault crossings,a tank battalion usually crosses in the second echelon. However, a tank battalion could cross in the first echelon in a weakly defended sector. A tank battalion crosses a river by fording, by going over bridges, by being transported aboard ferries or on tactical pontoon bridging, or by snorkeling. Although Soviet tank crews receive periodic underwater training, snorkeling is the least-preferred option. Some elements snorkel across at one site while others cross elsewhere by other means. Sealing arras arc [areas are] selected near concealed routes about 3 to 5 kilometers from the river. Snorkels are installed about 1 to 2 kilometers from the water barrier. Some tanks provide fire support for the crossing, and artillery is used for both direct and indirect fire. The far bank must be secured before tank snorkeling starts. Efficient traffic control is essential. If the traffic controller permits tank formations to mass, they become a lucrative target for enemy aviation and artillery. Tanks cross underwater in column formation at approximately 30 meter intervals. They cross at low speeds without shifting gears or halting. The tank must be halted to remove waterproofing before the turret can traverse and the main gun can fire.
I suspect the process remains much the same for the Russians
with that confirmed pretty much here
Russian Deliberate River Crossings: Choreographing a Water Ballet