{HEAD ~ An additional valve} 408 for coolant flow may be provided to control {TAIL ~ flow} of coolant only when the coring bit 104 is advancing 
provided to control
{ HEAD ~ An additional valve } 408 for coolant flow may be provided to control { TAIL ~ flow } of coolant only when the coring bit 104 is advancing
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH