operation closed

[19sbirro87]

Hello, I have to represent in detail a locking system commonly used in emergency exits, which allows the accompanied return of the door once opened......I can't understand the operation of the lock that mounts to the door....you know how to help me? ? ?

 

[meccanicamg]

the door lock is humid air cylinder / damp oil, like that of the luggage doors. This gas cylinder is mounted on a lever that reached a certain angle makes the active component of force along a short arm by winning the closing spring of the door.