The auxiliary blade is motivated to fold vertically pleatwise and, by alternating {HEAD ~ projection} of the folded auxiliary forward of the trailing edge of {TAIL ~ the main blade}, and a return to the overlying posture, respectively stop and reestablish the debris windrow 
The auxiliary blade is motivated to fold vertically pleatwise and , by alternating { HEAD ~ projection } of the folded auxiliary forward of the trailing edge of { TAIL ~ the main blade } , and a return to the overlying posture , respectively stop and reestablish the debris windrow
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH