The bars interdigitate with the teeth and thus pass through the narrow openings between the teeth where {HEAD ~ the knife edges} scrape {TAIL ~ the bars}, thereby cutting free any material adhering to or impaled upon the bag breaking bars 
scrape
The bars interdigitate with the teeth and thus pass through the narrow openings between the teeth where { HEAD ~ the knife edges } scrape { TAIL ~ the bars } , thereby cutting free any material adhering to or impaled upon the bag breaking bars
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH