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