When the wheels move along the rail, the rake tines travel along the openings in the screen, forcing {HEAD ~ any obstructing material} into {TAIL ~ another portion} of the material reduction apparatus 
into
When the wheels move along the rail , the rake tines travel along the openings in the screen , forcing { HEAD ~ any obstructing material } into { TAIL ~ another portion } of the material reduction apparatus
OTH OTH OTH 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