You should be able to find the parts you need specific for the application. Check out the attached graphic. There are such things as:

Concentric Brushsets - wires out the top, wires out the bottom, rotating middle. Given the harsh environment and alkali dust, I recommend getting an integrated, hassle free rig like this.

Compression bearings - hold up heavy turning things. It only actually makes sense in Location B, where it relieves loading on the Concentric Brushset. Some Brushsets are built to take weight, and basically have such a compression bearing built in, which is equivalent to having the bearing in Location A, and the additional compression bearing drawn at Location B is actually superfluous.

Flexible Bracing - this bracing should only keep the bottom of the brushset from rotating with the tower, and should be flexible and lightweight. There will be a lot of strange vibration in the tower. If this bracing is structural, the vibration will cause the brushset or the bracing to come unglued.

Structural Bracing and Ring Bearings- Make sure the rotating tower is cuffed in at least two burly ring bearings, encased in a solid structural base. If it falls over, you want the base to rotate through the fall with it, otherwise the bottom of the tower will ream out any innards inside the base, including brushsets, motors, and computers.

Interior Lip - to keep the brushset from sliding up into the base of the tower and getting the bottom non-rotating half of it jammed inside it.

I've left out the motor drive and the velocity/acceleration meter, which attach between the two ring bearings. There are certainly more details, but hope this helps. Over and out.