{HEAD ~ a locking assembly} to frictionally lock the breastplate to {TAIL ~ the shaft} at at least one arced groove 
{ HEAD ~ a locking assembly } to frictionally lock the breastplate to { TAIL ~ the shaft } at at least one arced groove
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH