{TAIL ~ The crusher} replaces the drilling machine upon completion of the drilling of {HEAD ~ a guide hole} by the drilling machine 
{ TAIL ~ The crusher } replaces the drilling machine upon completion of the drilling of { HEAD ~ a guide hole } by the drilling machine
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH