It's all very basic, from my Kirby selling days. You put the
palm of your hand over the open end of a hose while the machine is on! Your hand is tight against the open end. That is
suction! If you start to pull your hand away and you hear the
air flowing. That's just what dose the cleaning, air flow.
Back in the 70's (kirby classic) Kirbys had an adjustable
vent on the top of the carpet cleaning head. So when you vacuumed glued down looped carpet. You would have air flow to
pick up the dirt !
Norm