The braking unit applies {HEAD ~ frictional force} to {TAIL ~ the stopper} when the cover is opened 
to
The braking unit applies { HEAD ~ frictional force } to { TAIL ~ the stopper } when the cover is opened
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH