Patent ID: 8366578

Claim:
A gear train assembly comprising: a first reduction planetary gear set having a rotating carrier and a first reduction planetary gear rotatably coupled to the rotating carrier, the rotating carrier being rotatable about an axis in a primary direction, a second reduction planetary gear set having a non-rotating carrier, a second reduction planetary gear rotatably coupled to the non-rotating carrier, a sheath coupled to the rotating carrier, the sheath having a first sidewall, a second sidewall spaced apart from the first sidewall, and an outer surface positioned between the first sidewall and the second sidewall, the first sidewall being disposed on a first side of the rotating carrier, the second sidewall being disposed on a second side of the rotating carrier, wherein the first reduction planetary gear is partially disposed between the first sidewall and the second sidewall, and a vane disposed on the outer surface and positioned from a first end of the outer surface to a second end of the outer surface, wherein the vane is nearer the second reduction planetary gear set at the second end than at the first end.