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Lift mechanism systems and methods

  • US 8,286,927 B2
  • Filed: 04/07/2010
  • Issued: 10/16/2012
  • Est. Priority Date: 05/20/2003
  • Status: Active Grant
First Claim
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1. A lift mechanism, comprising:

  • a fixed component having proximal and distal ends;

    a movable component disposed in sliding or rolling engagement with the fixed component, the engagement including a contracted configuration in which the movable component is disposed a minimum distance from the fixed component distal end and an expanded configuration in which the movable component is disposed a maximum distance from the fixed component distal end;

    a wheel pivotally supported by one of the components about a pivot axis, the wheel comprising a pulley member and a cam member with an eccentric shape, the wheel having a rotational range of travel from a first angular orientation corresponding to the expanded configuration of the fixed and movable components to a second angular orientation corresponding to the contracted configuration of the fixed and movable components, wherein the rotational range of travel between the first angular orientation and the second angular orientation is less than one complete wheel rotation;

    a first cable connecting the cam member of the wheel to a spring for biasing the wheel to rotate in a first direction; and

    a second cable connecting the pulley member to one of the components so that the wheel rotates when the movable component is moved relative to the fixed component, wherein at least the first cable does not include metal but rather comprises a tensile polymer, wherein the cam member is shaped and positioned so that the first cable contacts the cam member at a first intersection disposed a first distance from the pivot axis when the wheel is disposed in the first angular orientation and the first cable contacts the cam member at a second intersection disposed a second distance from the pivot axis when the wheel is disposed in the second angular orientation, the first distance being different than the second distance.

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