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Sliding door operator

  • US 3,938,282 A
  • Filed: 02/01/1974
  • Issued: 02/17/1976
  • Est. Priority Date: 02/01/1974
  • Status: Expired due to Term
First Claim
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1. An automatic door operator used in opening and closing a door which is mounted upon a door frame for sliding movement in a vertical plane between open and closed positions in response to movement of traffic adjacent the door, said door operator comprising:

  • a drive cylinder for mounting relative to said door frame having first and second fluid inlets;

    a piston slideably movable within said drive cylinder through door opening and door closing strokes between said first and second fluid inlets;

    a drive means for connecting said piston to a door to drive the door through the door opening and door closing strokes;

    a means for supplying pressurized fluid from a suitable source thereof connected to said first and second fluid inlets and operable to supply pressurized fluid to either of said first and second fluid inlets;

    control means interconnecting said supplying means with said first fluid inlet and connecting said second fluid inlet to exhaust continuously throughout an opening stroke and connecting said supplying means to said second fluid inlet and connecting said first fluid inlet to exhaust continuously throughout a closing stroke;

    said control means including means for reducing the pressure of fluid acting on said piston from a side thereof in communication with one of said fluid inlets connected for supplying pressurized fluid to said cylinder after said piston has moved part way along on a stroke; and

    exhaust metering means metering the exhaust flow of fluid at least as the door approaches the end of its stroke.

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