Closable vane turbine ventilator

A turbine ventilator, comprising:

• a tubular skirt adapted to be secured in upstanding relation to the upper end portion of a ventilator shaft, or the like;
• a spider secured to the inner periphery of said skirt;
• an upstanding shaft coaxially supported at its depending end portion by said spider;
• a horizontally disposed disk-like rain plate coaxially journalled by the upper end portion of said shaft for angular rotation;
• a moveable plate-like ring horizontally surrounding said shaft above said skirt for vertical movement toward and away from said rain plate,
• said moveable ring having a depending flange telescopically surrounding the outer periphery of the upper end portion of said skirt and having radial inwardly projecting spokes;
• superposed clamp rings vertically slidably surrounding said shaft and impinging the inwardmost end portions of said spokes;
• a plurality of panel-like vanes extending vertically in circumferentially spaced relation between corresponding peripheral edge portions of said rain plate and said moveable ring in a like plurality of respective planes normally substantially tangential to a cylindrical plane generated by the periphery of said skirt,
• each said vane having a longitudinally extending tab centrally formed on its respective end forming upper and lower sets of tabs,
• each tab of at least one set of tabs having a quarter twist about its longitudinal axis to form opposing cam surfaces,
• said rain plate and said moveable ring each having a row of circumferentially spaced-apart apertures disposed in cooperative relation for receiving the respective upper and lower sets of tabs,
• at least one row of said rows of apertures comprising vertical slots for receiving said set of quarter twisted tabs and slidably engaging said tab cam surfaces;
• a plurality of fasteners connected with the end of each tab of said sets of tabs projecting through said rain plate and said moveable ring, respectively;
• and,
• lever means interposed between said moveable ring and said skirt and secured to said shaft for lifting said moveable ring toward said rain plate,
• at least one set of said sets of tabs angularly rotating said plurality of vanes in unison through an arc of predetermined magnitude in response to movement of said moveable ring toward said rain plate.