Hoist system having triangular tension members

摘要

A hoist system having triangular suspension bands minimizes sway and twisting during the lifting of a payload. The system includes three depending retractable and extensible triangular tension members which provide three sets of opposed horizontal tensile forces aligned along three non-parallel lines. Each tension member comprises a flexible triangular band attached along one side to one of three rotatable spools arranged at 60 DEG to each other. The bands are attached near their vertices to a payload gripper assembly which is raised or lowered as the bands are wound or unwound from the spools. The three triangular bands provide six horizontal force components which provide good lateral stability and torsional rigidity, thereby minimizing sway and twisting of the payload. The bands also provide good payload lifting strength.