THREE STAGE MAST

摘要

The present invention is directed to an apparatus and method for raising and lowering a three-stage forklift mast assembly having a reduced overall lowered height. A first linkage system on the outer and middle masts creates a 2:1 movement ratio of the middle mast with respect to movement of a piston arm in the first linkage system. A second linkage system on the middle and inner masts creates a 2:1 movement ratio of the inner mast with respect to the movement of the middle mast and an overall 4:1 movement ratio with respect to the movement of the piston arm in the first linkage system. A third linkage system on the inner mast creates a 2:1 movement ratio of a set of forks on the inner mast with respect to the movement of a piston arm in the third linkage system, allowing free lift of the forks.