GB1293301A - Extensible ladder - Google Patents

Abstract

1293301 Extensible ladders; convertible ladders W KUMMERLIN and N A KUMMERLIN 1 Jan 1971 [14 Jan 1970] 50/71 Heading E1S A telescopically extensible ladder comprises at least two ladder sections, the stringers 713 of one ladder section 714 being longitudinally slidable within the stringers 704 of another ladder section 702, and each of the rungs of the section 702 being longitudinally divided into two parallel parts 705, 705' spaced apart to allow the rungs 723 of the section 714 to pass between them. The stringers are preferably U-section bars, with the open sides of stringers 704 and 713 facing in opposite directions, as shown, or the same direction (Fig. 1, not shown). The rungs may also be U-section bars (Fig. 1), or cylindrical tubes having flattened ends, as shown, or tubes of parallelogram-cross-section, which latter may have non-slip treads inserted (Fig. 8, not shown). Two such extensible ladders may be pivotally connected at their upper ends to form a convertible long and step ladder, which includes a releasable fastening 946, and in which the inner rungs 923 and outer rung parts 905 are trapezium-section bars with tread surfaces 948, 949 on both sides disposed at such an acute angle that the rungs have horizontal upper surfaces in both positions of the convertible ladder, the. long ladder being used at the appropriate inclination.