The linkage mechanism allows the door to move between a closed position where {HEAD ~ the door} is placed against the housing and in front of the opening to prevent access therethrough, and an opened position where the door is placed away from the opening to allow {TAIL ~ access} therethrough 
The linkage mechanism allows the door to move between a closed position where { HEAD ~ the door } is placed against the housing and in front of the opening to prevent access therethrough , and an opened position where the door is placed away from the opening to allow { TAIL ~ access } therethrough
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH