a vent follower which moves in relation to said vent position, said follower rigidly attached to said shaft so as to rotate said shaft when said vent follower moves, said vent follower extending between said shaft and said inside surface and said top and bottom plate, said {HEAD ~ vent follower} forming {TAIL ~ a movable seal} at said inside surface and said top and bottom plate 
a vent follower which moves in relation to said vent position , said follower rigidly attached to said shaft so as to rotate said shaft when said vent follower moves , said vent follower extending between said shaft and said inside surface and said top and bottom plate , said { HEAD ~ vent follower } forming { TAIL ~ a movable seal } at said inside surface and said top and bottom plate
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH