| 摘要 |
Security of a door 1 is enhanced by fitting a U-shape channel section 3 of steel to its shutting edge 2 throughout the full door-height, and clamping the limbs 6, 7 of the section 3 together by bolts 8 with the margin of the shutting edge 2 sandwiched between. Rods 9, 10 actuated by a crank mechanism 11 slide upwards and downwards respectively within tubes 12, 13 for fastening the door 1, and are locked by the bolt 18 of a dead lock 17 shot into a slot 19 in the rod 9. The limbs 6, 7 of the channel section 3 are of different lengths, and the tubes 12, 13, the crank mechanism 11 and the dead lock 17 are all mounted on the longer limb 7 on the inside of the door 1. The shorter limb 6 overlaps the edge of a steel facing sheet 5 on the outside of the door 1. As an alternative (Figure 3), two channel sections 23, 24 are provided at the top and bottom respectively, of the door 21 with portions bridging the top and bottom door-edges 27, 28. Bushes 29 for restraining and guiding the boltwork 30, 31 are mounted on the channel sections 23, 24. <IMAGE>
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