Patent ID: 7004288

Claim:
A lift apparatus for use with a ladder having two spaced upright stringers and a plurality of horizontal rungs bridging the stringers and spaced at a distance vertically from one another, the lift apparatus comprising: a frame; a prime mover mounted on the frame and having a rotatable output shaft; at least one pair of sprocket systems spaced apart vertically from each other, at least one of the sprocket systems being operatively coupled with the output shaft of the prime mover; endless driving force transmitting means passing around the pair of the sprocket systems; controller means for controlling the prime mover in such a manner as to selectively rotate the output shaft thereof in order to move the endless driving force transmitting means in a forward or reverse direction, or stop it; gripper elements being carried by said endless driving force transmitting means and spaced at a distance substantially corresponding to that of the rungs of the ladder, said gripper elements engaging the horizontal rungs with said frame being moved up or down the ladder in correspondence with the movement of the endless driving force transmitting means; and a platform secured to the frame for supporting an operator thereon.