Collapsible security grille

Abstract

A collapsible security grille is provided comprising two conventional face-to-face sets of rigid grille bars (2, 9) pivotally interconnected at their intersections, wherein all the pivotal connectors (4) are uniformly and non-adjustably spaced apart along their respective grille bars in one said sets, but are free, as far as the second set is concerned, to undergo small sliding displacements along the grille bars of that set. In this way the stresses that ordinarily lead to jamming, jerky action and noise are automatically compensated at the point and instant of their origin. It is preferred that the pivotal connectors around the periphery of the second set are likewise non-adjustably spaced apart, so that every such connector at a grille bar meeting point (6) (as distinct from a crossing point 8) is spaced from both of the two next adjacent crossing-point connectors (8). A spacer member (7) suitable for this purpose can be made integral with a pivotal connector, and can be made in two parts (28, 31; 29 30) for length adjustment prior to use. The length of the spacer in use determines the pitch of the grille.

Dependencies are inferred from the claim text.