{HEAD ~ The ratchet} allows {TAIL ~ the mill} to move away from the object when the drill string is rotated in the first direction and lifted relative to the mandrel 
allows
{ HEAD ~ The ratchet } allows { TAIL ~ the mill } to move away from the object when the drill string is rotated in the first direction and lifted relative to the mandrel
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH