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