Whether the heads will move or not, I don't know.
But the welding of the head to the frame is in no way a barrier to the head moving. The beam could be temporary while they install the mechanism (which could be in the body with steel wires going to the head).
The spires of BSO had literally hundreds of beams that stuck out further than they needed in order to put scaffolding on them. When done with the concrete work, and the scaffolding was coming down, they just torched the extending beams off.
But the welding of the head to the frame is in no way a barrier to the head moving. The beam could be temporary while they install the mechanism (which could be in the body with steel wires going to the head).
The spires of BSO had literally hundreds of beams that stuck out further than they needed in order to put scaffolding on them. When done with the concrete work, and the scaffolding was coming down, they just torched the extending beams off.