| 摘要 |
Described is a door unit with a door which can be raised overhead, such as a jointed pull-up door, and with vertical frame spars fixed round the edge of the doorway and with a guide-rail system in whose rails the door is fitted so that it can be displaced along the rails and with ropes which hold the door, the ropes passing over pulleys and being attached to a fixed shaft. In order to prevent unauthorized opening of the door, the door has a latch assembly which is attached to at least one side of the door and which acts on the rope on this side of the door, the latch assembly having a latch which engages, when the door is raised, with a catch in the vicinity of at least one of the spars if this rope becomes slack. |
