| 摘要 |
A safety device for automatically closing a door in response to a predetermined condition, such as fire, is provided by a selectively disengageable brake operatively associated with a pivotable door closure arm. The brake includes a flexible cable wrapped around a brake drum, and means to selectively tighten the cable around the drum. A crank-pin rotates conjointly with the drum and engages the door closure arm to expeditiously close the door in the event of fire. |
