Patent ID: 7484712

Claim:
A hoist assembly for raising and lowering a load attached to a plurality of cables comprising: a fixed frame detached from the load; a stationary drum mounted within said frame, said drum configured for rotational motion and having an outer surface with a groove spirally disposed about said outer surface with a predetermined pitch, wherein said groove is configured to receive the plurality of cables wound about the drum, and having a cable take-off point associated with each cable where the cable ceases contacting said drum and where the cable is tangent to said drum, defining a fleet angle for each cable between the centerline of said groove and the cable; a plurality of head blocks, each head block configured to receive at least one cable as said cable is wound and unwound on said drum, said head blocks configured to maintain tangential alignment of each of said plurality of cables with said associated take-off point, wherein said head block maintains said fleet angle of each cable at substantially zero degrees; a head block guide assembly having a first head block guide track and a second head block guide track mounted on said frame spaced apart and parallel to each other; and at least one of said head blocks positioned between said first and second head block guide tracks, said at least one head block having a plurality of wheels disposed within said first and second head block guide tracks, wherein said at least one head block is free to move along said guide track; and said head blocks being mounted to said head block guide assembly allowing for synchronized translational movement of said head blocks relative to said stationary drum along said frame maintaining alignment with each take-off point.