Turrets only want one degree of freedom: spinning. 148 (and lots of other turrets) achieves this by using a "bearing sandwich."

Their shooter is attached to the light gray gear on the left, with another dark gray ring on the bottom.

The part of note here is the three bearings stacked together. The larger light gray bearings on top and bottom sandwich the turret base, restraining its up and down movement.

The blue bearing in the middle rotates, spinning against the turret base. These stacks of bearings are all around the turret, so it can't move horizontally either.

Each bearing is holding the turret base in place, so that the only thing that can move is the rotation of the shooter.