GB1476806A - Ladders for inspection shafts - Google Patents

Abstract

1476806 Ladders for inspection shafts BETONVAREFABRIKEN SJAELLAND AS and I C HALVORSEN & SONNER AS 13 Sept 1974 [14 Sept 1973 13 June 1974] 40066/74 Heading EIS A ladder for an inspection shaft, e.g. for a sewer, comprises at least two ladder elements hooked together, each having spacers for engaging the inner wall of the shaft, one ladder element of each pair having coupling means for engaging the other element at front surfaces of parts at the end and at rear surfaces of parts spaced from the end of the other element. In Figs. 4 and 5, the coupling means are upper ends of the stiles 12, 13 of the lower element which are bent to form hooks 16, 17; these upper ends engage the front of the end rung 8 of the upper element and the hooks engage the rear of the next rung 7 and the stiles 1, 2. The ends of either rungs or stiles may be bent to form the spacers 15. The topmost element is formed to hook over the top edge of the shaft. In other embodiments, the hooks engage over a rung near the end and the stile ends of the lower element engage the front of either a rod fixed parallel to the rung or bent ends of the stiles of the upper element; or the hooks are replaced (see Fig. 27) by plates 53 having slots 54 to receive lugs, which may be spacers 48, on the stile ends 45 of the upper element, the plates either engaging the rear of or, as shown, having slots 55 to receive the rung 46 near the end. In general, the ladder elements are prevented from being disconnected inside the shaft by relative rotation being required to disconnect adjacent elements.