According to the US Patent and Trademark Office, the invention relates to a “lift assembly having a drum rotatably mounted to a frame and linearly translatable with respect to the frame. A plurality of head blocks are connected to the frame along a helical mounting path, wherein linear translation of the drum during takeoff or take-up maintains a predetermined fleet angle between a take off point from the drum and the head block.”

The inventor was issued US Patent Number 6,889,958 on May 10 2005.

The original application was filed on October 21 2003.