The cylinder pushes down on the drawbar to release the tool in the same manner as the Lever Draw Bar does on the Pulsar. Tormach's Power Draw Bar works the same way. There is a spindle nut which prevents loading the spindle bearings. If you take a look at Brian's video you can see the spindle nut is threaded on the top of the draw bar above the lower plate.

Ray's PDB for the Torus spins the drawbar.

Steve