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