In this method, in the case of trapping {TAIL ~ the movement} of {HEAD ~ the rear pane} in the lowering direction is stopped and the rear pane is reversed, i.e. moved in the lifting direction 
In this method , in the case of trapping { TAIL ~ the movement } of { HEAD ~ the rear pane } in the lowering direction is stopped and the rear pane is reversed , i.e. moved in the lifting direction
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH