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