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