The coring bit may be engaged to {HEAD ~ a motor} for rotating {TAIL ~ the coring bit} 
for rotating
The coring bit may be engaged to { HEAD ~ a motor } for rotating { TAIL ~ the coring bit }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL