主权项 |
1. A fall arrestor for a vertical door having a planar vertical edge extending adjacent to a fixed vertical rail, and having a lift mechanism for lifting and lowering the door with a power driven mechanism connected to a first end of a lift cable, said fall arrestor comprising:
a first member connected to a second end of the lift cable and having a top surface; a second member connected to the vertical edge of the vertical door and having a surface opposed to said top surface of the first member; a first compression spring extending between said top surface of the first member and the opposed surface of the second member; a pair of latching dogs pivotably supported with respect to the first member on opposite sides of said fixed vertical rail, the pair of latching dogs having an open position wherein said pair of latching dogs are separated from the vertical rail and a closed position wherein said pair of latching dogs bear against planar faces of the opposite sides of the vertical rail to lock the vertical door to the vertical rail, preventing motion of the vertical door relative to the vertical rail; a pair of cam members rotatably supported on the first member and connected to the pair of latching dogs to place the pair of latching dogs in said open position when the top surface of the first member and the opposed surface of the second member are in a compression position, and to place the pair of latching dogs in said closed position when the top surface of the first member and the opposed surface of the second member are in a separated position; and wherein a weight of the vertical door, when being lifted or lowered, acts to impose tension on said lift cable to maintain the top surface of the first member and the opposed surface of the second member in said compression position, compressing the compression spring, and maintaining said pair of latching dogs in said open position, and when the vertical door is completely closed or the lift mechanism fails, the compression spring forces the top surface of the first member and the opposed surface of the second member apart and, acting through said cam members, forces the pair of latching dogs into said closed position, locking the vertical door to the vertical rail. |