Rocking back and forth of {TAIL ~ the turnable member} acts through the clutch teeth and {HEAD ~ sprags} to turn the intermediate member 
Rocking back and forth of { TAIL ~ the turnable member } acts through the clutch teeth and { HEAD ~ sprags } to turn the intermediate member
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH