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