That's the T-28. Panther F posted a great video on it last week. Wish we hand more like that.

Here are some pics that show the size of our huge T-30. The tank had the "new" Allison CD tranny and could theoretically pivot...BUT, 72 tons with 8 road wheels length on the ground, it would have dropped a track or dug itself into and soaft ground. The T-29 thru T-34 were about the same size with mostly 120mm guns.

The photos; me at rear of turret. It's so big, you almost have to use the MG stowage pintle as a step to get onto the turret.
A shot of ther breech end....that is a HUGE recoil system and breech that takes up the entire inside. At upper center left is the crane.
A photo of the projo rammer. That spring is super strong...can hear it slam about 3 blocks away.
A shot lf looking over the turret from the TC hatch and looking rear from the mantlet. The turret top feels like a Navy carrier deck.