Patent ID: 6029585
Filing Date: 2000-02-29
Classification: B66F

Abstract:
A lift mechanism comprising:a lower bracket to be attached to a base;a lower support arm pivoted at one end thereof to the lower bracket to form a first pivot of the lower support arm, and a lower drive arm pivoted at one end thereof to the lower bracket to form a first pivot of the lower drive arm positioned obliquely downward from the first pivot of the lower support arm;an intermediate bracket for pivotally supporting free ends of the lower support arm at a second pivot of the lower support arm and the lower drive arm at a second pivot of the lower drive arm, wherein the distance between the first pivots of the lower arms is equal to the distance between the second pivots of the lower arms with the arms in parallel to each other;lift control means disposed on the intermediate bracket and having a movable member retractably projectable in a longitudinal direction parallel to the base;an upper support arm and an upper drive arm pivoted each at one end thereof to the intermediate bracket to form a first pivot of the upper support arm and a first pivot of the upper drive arm, the first pivots being respectively symmetric about the lift control means with the second pivot of the lower support arm and the second pivot of the lower drive arm;an upper bracket for pivotally supporting the other ends of the upper support arm at a second pivot of the upper support arm and the upper drive arm at a second pivot of the upper drive arm, wherein the distance between the first pivots of the upper arms is equal to the distance between the second pivots of the upper arms with the upper arms in parallel to each other; andtraction members attached each at one end thereof to an outer end of the movable member of the lift control means and connected at the other ends thereof to respective mount portions formed on the lower drive arm and the upper drive arm at their ends pivoted to the intermediate bracket.