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