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