{HEAD ~ said door} being slidably mounted on {TAIL ~ said box} for selective opening and closing of a discharge slot along the width of said hopper bottom 
slidably mounted on
{ HEAD ~ said door } being slidably mounted on { TAIL ~ said box } for selective opening and closing of a discharge slot along the width of said hopper bottom
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH