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Height adjusting device for a chair

  • US 5,749,557 A
  • Filed: 05/23/1996
  • Issued: 05/12/1998
  • Est. Priority Date: 05/23/1996
  • Status: Expired due to Fees
First Claim
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1. A height adjusting device comprising:

  • an inner tube having an upper end and a lower end;

    a bushing fixedly connected with the lower end of the inner tube and defining internal threads;

    a positioning tube having an upper end and a lower end, a sleeve securely mounted in said upper end of said positioning tube and having an inner diameter slightly greater than an outer diameter of said inner tube for fitting and partially receiving the inner tube and allowing axial and rotational movement of said inner tube, and a base plate securely mounted to the lower end of the positioning tube and having a central hole and a plurality of downward protrusions arranged around the central hole;

    a screw defining a threaded upper section for the bushing to be screwed thereto and to be moved therealong and a reduced lower section, said threaded upper section comprising a top and bottom blocking means for limiting the traveling of the bushing therealong between a top position and a bottom position, said reduced lower section defining a bottom and extending through the central hole of the base plate;

    a bearing assembly and a spring mounted around the reduced lower section of the screw and located between the base plate and the threaded upper section of the screw; and

    an engaging member fixedly attached to the bottom end of the reduced lower section of the screw and defining a plurality of upward protrusions for releasably engaging with the downward protrusion defined in the base plate.

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