a sleeve having a pair of inner teeth gears engaged with said outer teeth gears for transmitting {HEAD ~ power} between {TAIL ~ the rotary shafts} 
between
a sleeve having a pair of inner teeth gears engaged with said outer teeth gears for transmitting { HEAD ~ power } between { TAIL ~ the rotary shafts }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL