an inner race and an outer race, said {TAIL ~ races} defining {HEAD ~ an annular space} therebetween 
an inner race and an outer race , said { TAIL ~ races } defining { HEAD ~ an annular space } therebetween
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH