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