Patent ID: 7967717

Claim:
A variable drive apparatus, comprising: a hollow shaft; an inner shaft or spindle lying inside said hollow shaft, and supported on said hollow shaft freely rotatable relative to said hollow shaft in complete revolutions; a drive gear constructed as a differential speed gear selected from the group consisting of a planetary gear and a harmonic drive gear; and a first drive device connected to said drive gear and a second drive device connected to said drive gear; wherein said drive gear is connected between said hollow shaft and said inner shaft or spindle for selective operation in three operating modes, including: a first operating mode in which said drive gear is coupled between said first drive device, said hollow shaft, and said inner shaft or spindle for synchronously driving said hollow shaft and said inner shaft or spindle with only said first drive device; a second operating mode in which said inner shaft or spindle is freely rotated independently of said hollow shaft with only said second drive device and while said first drive device and said hollow shaft are stationary; and a third operating mode in which said hollow shaft and said inner shaft or spindle are non-synchronously driven by said first drive device and said second drive device, respectively.