u/FarSeries2172

There's 2 swivel bearings. One is locked and the other unlocked so that it can squeeze the pillar. and I used a valve to control the locked bearing.
Another thing is I had to build it sideways and then rotate it 90 degrees because apparently only the upper and lower faces of belts can move along blocks. if you just make a vertical belt it will stick to the pillar but it wont move, instead only the tiny faces on the edges will move along blocks.