Patent ID: 6044927
Filing Date: 2000-04-04
Classification: B66F

Abstract:
A scissors work platform lift machine, comprising:(a) a chassis;(b) a work platform disposed above said chassis;(c) a scissors lift mechanism having a plurality of portions pivotally movable relative to one another, an upper end portion pivotally mounting said work platform above said chassis and a lower end portion pivotally mounted on said chassis, said pivotally movable portions being movable vertically between retracted and expanded conditions so as to move said work platform between lowered and raised positions relative to said chassis; and(d) an electro-mechanical actuation arrangement extending between and being mounted to selected upper and lower ones of said pivotally movable portions of said lift mechanism and adapted to operate said lift mechanism between said retracted and expanded conditions, said actuation arrangement having a telescopable contractable and extendable component capable of varying in length and operable to undergo rotation in a first angular direction and translational contraction in length in a first linear direction so as to cause movement of said lift mechanism vertically toward said retracted condition and thereby movement of said work platform toward said lowered position and to undergo rotation in a second angular direction opposite to said first angular direction and translational extension in length in a second linear direction opposite to said first linear direction so as to cause movement of said lift mechanism vertically toward said expanded condition and thereby movement of said work platform toward said raised position, said telescopable component of said actuation arrangement including:an externally threaded ballscrew shaft having opposite first and second ends and being rotatable in said opposite first and second angular directions;an internally threaded nut threadably rotatable on said ballscrew shaft and in response to rotation of said ballscrew shaft in said opposite first and second angular directions being movable in said opposite first and second linear directions between a retracted position wherein said nut is located adjacent to said first end of said ballscrew shaft and an extended position wherein said nut is located adjacent to said second end of said ballscrew shaft; andan extension tube having opposite first and second ends and being attached at said first end to said nut for undergoing movement therewith in said opposite first and second linear directions and spaced radially outwardly from and extending over and axially along said ballscrew shaft to said second end of said extension tube being disposed adjacent to said second end of said ballscrew shaft when said nut is in said retracted position and spaced from said second end of said ballscrew shaft when said nut is in said extended position.