Metal cellar door structure - comprises narrow standard U=shaped component fitted together in staggered formation

摘要

The metal cellar door comprises several narrow standard components (2) which are bent into a U-shape in the lengthwise direction, and fitted together in a staggered formation. This allows the desired width to be achieved by relative sliding of the standard components. The standard components have upturned edges, so that they form very wide shallow U-sections. The components are set so that their upturned edges face alternately outward and inward, when the door is at its widest setting the edges are in contact.