Inside the collection chamber assembly the air is filtered, {HEAD ~ the chalk dust} remaining in the collection chamber of the assembly, while {TAIL ~ filtered air} is exhausted by the suction device 
Inside the collection chamber assembly the air is filtered , { HEAD ~ the chalk dust } remaining in the collection chamber of the assembly , while { TAIL ~ filtered air } is exhausted by the suction device
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH