Patent ID: 7874544
Filing Date: 2011-01-25
Classification: B66C,B66F,H04R

Abstract:
1. A lifting device, comprising: a frame comprising two ends that are opposite from each other along a first axis of the frame, at least two multi-stage masts, each multi-stage mast corresponding to another multi-stage mast to form a pair of multi-stage masts, each multi-stage mast of a pair of multi-stage masts being attached to a respectively opposite end of the frame in an upright configuration with respect to the frame and substantially axially aligned with the other multi-stage mast of the pair of multi-stage masts, the axial alignment of the pair of multi-stage masts being substantially parallel to the first axis of the frame, each multi-stage mast comprising a first length configuration and a second length configuration, the second length configuration being longer than the first length configuration, each multi-stage mast further comprising a plurality of stages, at least one stage of a mast being vertically movable with respect to at least one other stage of the mast; and a cable mechanism coupled to each multi-stage mast, the cable mechanism comprising: