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