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