GB650616A - Improvements in or relating to flexible ladders - Google Patents

Abstract

650,616. Flexible ladders. HUDSON, A. N., STUDD, S. D., and WILLIAMS, W. Oct. 29, 1947, Nos. 28848 and 32409. [Class 20(ii)] A flexible ladder, e.g. a fireescape, has side members, formed of alternate main links 10, Fig. 1, and U-section short links 11, alternate links 11 in each side member being all oppositely disposed to the other links 11 so that the ladder is constrained by rule-joint action to fold in zig-zag formation with its main links 10 superposed as shown in Fig. 3. The rungs 14, Fig. 1, which are channel-shaped with folded-over edges, are welded to the links 11 and W-shaped wallengaging members 16 are secured to the links 11 and rungs 14. The uppermost links 10 are connected to a pair of plate-link chains 9 extending across a window sill 20 and secured to anchorage brackets 21 within the building. A curved tube 25, detachably mounted at the window serves as a guide for the ladder when extending it. In a modification shown in Fig. 4, the main links 10 are about half the length of those shown in Figs. 1, 3 and alternate U- shaped links 11 only are connected by rungs 14 and wall-engaging members 16: In the collapsed ladder in this case, all the superposed members 16 are disposed within the stack which, for a given length of ladder, is approximately twice the height and half the depth of the stack shown in Fig. 3. Where a projecting ledge causes the ladder to hang clear of the wall means may be permanently mounted on the wall for securing the ladder. Thus a pair of toggle links 31, 32, Fig. 5, the link 31 being hooked at 33 for engagement with a rung 14, is actuated by a lever 36 which is locked by a pin 38. The lower end of the ladder may be anchored to the ground as shown in Fig. 7 and may be extended as a chair or provided with a harness or cradle. The attachments of the side members within the building may be provided with spring shock-absorbers. According to the first Provisional Specification the ladder may be housed in a casing on the outside of the building and may be raised by cords in the manner of a venetian blind.