{HEAD ~ Doors} or gates are provided to control {TAIL ~ the amount} and width of the discharge of particulate material to the highway surface 
{ HEAD ~ Doors } or gates are provided to control { TAIL ~ the amount } and width of the discharge of particulate material to the highway surface
HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH