DOOR, PREFERABLY FOR INDUSTRIAL BUILDINGS

摘要

This specification relates to a closure or door preferably for industrial buildings and is of the type in which the door leaf or sheet of flexible material is suspended over the opening by securing its upper edge and being opened or closed by raising or lowering its lower edge. The raising and lowering is carried out by means of a pair of ropes or the like that are connected to a hoist member, each rope extending within a respective separate channel extending along a vertical side of the opening, each rope or the like being connected to the lower portion of the leaf through a protection means that prevents uncontrolled lowering. This protection means, in response to a predetermined decrease in the load on the rope, is released to lock the lower portion of the leaf to the respective guide bar. The protection means includes a spring biased rod that is movable relative to the leaf and is connected to the respective ropes, the rod being connected by links to locking mechanism having dogs that are pivoted in cross-wise arrangement on a common shaft. The arrangement is such that under the action of the spring, the rod drives the links so as to cause outward movement of both ends of each dog and into engagement with the lateral flanges of the associated guide bar at any position of the lower portion of the leaf relative to the guide bars so as to lock the leaf against movement relative to the guide bars unless the tension in the ropes is of sufficient magnitude to override the action of the springs.