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