an air flow passage through which grass cuttings are discharged from said cutting chamber in {HEAD ~ a current} of {TAIL ~ air} 
of
an air flow passage through which grass cuttings are discharged from said cutting chamber in { HEAD ~ a current } of { TAIL ~ air }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL