The linkage mechanism allows the door to move between a closed position where 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 {HEAD ~ the opening} to allow {TAIL ~ access} therethrough 
to allow
The linkage mechanism allows the door to move between a closed position where 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 { HEAD ~ the opening } to allow { TAIL ~ access } therethrough
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