They had one of those at Tire Farm in Farmingdale, NJ when I was a kid. If memory serves it helps to seat the bead on those trouble prone "new fangled" tubeless tires!
While you've got an air hose clipped on the stem blowing in air to inflate the new tire, compressed air is blown out along the lower gap you see to help the bead "catch" and then normal inflation can take place.
Actually a very practical unit that makes seating those troublesome tire beads a snap! There have been days I wish I had one of these! (no space, no real need, thanks anyway)
The wheel rim sat on the inner circle, the tire on the outer circle making a seal of sorts with the metal. You've located the top bead to seal against the wheel by lifting up on the tire. A huge blast of air comes out of the groove you see between the inner and outer circles. The air you are putting into the stem is met by the huge blast of exterior air which forces the tire to inflate and seal against the lower rim seat.
Ever been to a tire shop and heard those huge loud blasts of compressed air? This is / was one of the sources of the air noise.
Basically a stationary version of This type of modern portable unit.....
http://www.gesusa.com/The-Tornado-p/105431.htm
Dave
