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