First, {HEAD ~ the unitary, shielded, perforate threaded collars} 42 are screwed onto the protruding threaded ends 34 of the bolts and tightened to jam {TAIL ~ the nuts} 40 against loosening 
First , { HEAD ~ the unitary , shielded , perforate threaded collars } 42 are screwed onto the protruding threaded ends 34 of the bolts and tightened to jam { TAIL ~ the nuts } 40 against loosening
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH