The trays are mounted on a generally cylindrical carousel which is rotated about its axis to bring successive ones of the trays into {HEAD ~ position} for loading wafers on to the trays and unloading {TAIL ~ wafers} from the trays 
The trays are mounted on a generally cylindrical carousel which is rotated about its axis to bring successive ones of the trays into { HEAD ~ position } for loading wafers on to the trays and unloading { TAIL ~ wafers } from the trays
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH