The cranks confine the motion of {HEAD ~ each} of the transmission rings to {TAIL ~ a non rotary}, planetary motion 
The cranks confine the motion of { HEAD ~ each } of the transmission rings to { TAIL ~ a non rotary } , planetary motion
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH