IL267175B2 - Self-supporting standing ladder - Google Patents

Description

Self-supporting standing ladder Field of the InventionThis present invention relates to self-supporting standing ladders.

Background of the InventionSelf-supporting standing ladders include a front leg, a rear leg, and a hinge- joint pair on opposite sides of a standing ladder for enabling opening and folding an upright standing ladder between an upright folded position and an upright open position. Self-supporting standing ladders can be unilaterally or bilaterally ascendable. The hinge-joint pair is pivotal between a folded position and a 180 ° degree open position. Standing ladders employ an opening restraint pair for limiting opening an upright open standing ladder to a maximal opening. Suitable opening restraints have a non-stretchable length and are flexible. Suitable opening restraints include inter alia straps, chains, wires, and the like. Suitable non- stretchable materials for opening restraints include inter alia metal, plastic, and the like. In accordance with Israel Standard 1847 part 1: Ladders: Terms, types, functional sizes dated November 2015, a front leg subtends an inclination α with respect to the horizontal and a rear leg subtends an inclination β with respect to the horizontal in which both inclinations α and β have a minimal 65 ° value and a maximal 75 ° value. In the event of a failure of one or both the opening restraints due to wear and tear, misuse, and the like, an upright open standing ladder is prone to completely collapse in the sense that its front leg and rear leg do the splits.

Some standing ladders are provided with two opening restraint pairs at different heights to reduce the load borne by each opening restraint pair during use. The provision of two opening restraint pairs acts as a safety measure in an event of a failure of an opening restraint during use to preclude collapse of an upright open standing ladder.

US Patent Application Publication No. 2017/0204662 to Perdue entitled Safety Step Ladder discloses a safety stepladder including supplementary support 30 legs which are able to move between an expanded and collapsed configuration. In their expanded configuration, each support leg forms a third leg of a tripod-like structure.

US Patent Application Publication No. 2010/0236806 to Huang entitled Stepladder discloses a stepladder has a front leg, a rear leg, a bracket and multiple steps. The front leg has two front side rails and multiple rungs mounted between the front side rails. The rear leg is connected pivotally to the front leg and has two rear side rails, a crossbeam and a lock. The lock is mounted pivotally on the crossbeam. The bracket is connected pivotally and slidably to the rear leg and has multiple pivot pins. The steps are mounted pivotally on the bracket and are selectively and engaged respectively with the rungs of the front leg. The lock selectively hooks a pivot pin to stably lock the bracket for improved safety.

There is a need for self-supporting standing ladders precluding collapse during use.

Summary of the InventionThe present invention relates to self-supporting standing ladders including a safety hinge-joint pair for enabling opening and folding an upright standing ladder between a folded position and an open position and an opening restraint pair distanced from the safety hinge-joint pair for limiting opening an upright standing ladder to an intended maximal opening. Each safety hinge-joint subtends an included acute angle γ at the intended maximal opening of an upright standing ladder as restricted by its opening restraint pair. Each safety hinge-joint includes an integral restrictor for limiting its maximal opening to an open safety hinge-joint limit in which it subtends an included angle δ where δ ≥ γ and δ does not exceed a maximum permitted angle such that a safety hinge-joint pair prevents an upright open standing ladder from collapsing in a failure of its opening restraint pair. A safety hinge-joint pair can secure an upright standing ladder in the same open position as its opening restraint pair. Alternatively, a safety hinge-joint pair can secure an upright standing ladder at a slightly more open position than its opening restraint pair not exceeding a maximum permitted angle. Brief Description of the DrawingsIn order to understand the invention and to see how it can be carried out in practice, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings in which similar parts are likewise numbered, and in which: Fig. 1 is a front perspective view of a conventional upright unilaterally ascending self-supporting standing ladder in its intended maximal opening with a close-up view of an open hinge-joint; Fig. 2 is a front perspective view of the Figure 1 standing ladder in a folded position with a close-up view of a folded hinge-joint; Fig. 3 is an exploded view of a safety hinge-joint with a pivot stopper integral restrictor in accordance with a preferred embodiment of the present invention; Fig. 4 is a front elevation view of a folded Figure 3 safety hinge-joint; Fig. 5 is a front elevation view of an open Figure 3 safety hinge-joint; Fig. 6 is a front elevation view of a folded safety hinge-joint with a fixed length integral restrictor in accordance with another preferred embodiment of the present invention; Fig. 7 is a front elevation view of an open Figure 6 safety hinge-joint; Fig. 8 is a front elevation view of a folded safety hinge-joint with a hinge-joint integral restrictor in accordance with yet another preferred embodiment of the present invention; and Fig. 9 is a front elevation view of an open Figure 8 safety hinge-joint.

Claims (3)

267175/ Claims

1. A self-supporting standing ladder comprising: (a) a front leg including a left front leg rail, a right front leg rail, and a set of rungs therebetween; (b) a rear leg including a left rear leg rail, a right rear leg rail, and a set of rungs therebetween; (c) a safety hinge-joint pair on opposite sides of the standing ladder for enabling opening and folding the standing ladder between an upright folded position and an upright open position, each safety hinge-joint includes a first safety hinge-joint member having a free upper first safety hinge-joint member end and a free lower first safety hinge-joint member end, a second safety hinge-joint member having a free upper second safety hinge-joint member end and a free lower second safety hinge-joint member end, and a safety hinge-joint pivot to pivot said free upper first safety hinge-joint member end with said free upper second safety hinge-joint member end; and (d) an opening restraint pair of non-stretchable flexible straps on opposite sides of the standing ladder and distanced from said safety hinge-joint pair for limiting an upright standing ladder to an intended maximal opening, each said safety hinge-joint including an integral restrictor for limiting its opening to an open safety hinge-joint limit, each said safety hinge-joint subtending an included acute angle γ as restricted by said opening restraint pair and an included acute angle δ at said open safety hinge-joint limit where δ ≥ γ and δ does not exceed a maximum permitted angle such that said safety hinge-joint pair prevent the upright open standing ladder from collapsing in a failure of said opening restraint pair wherein said integral restrictor is constituted by a pivot stopper restrictor, said first safety hinge-joint member being formed with a first transverse pivot stopper flange towards said free upper first safety hinge-joint member end 267175/ and said first transverse pivot stopper flange having a leading transverse pivot stopper flange end towards said free upper first safety hinge-joint member end, said second safety hinge-joint member being formed with a second transverse pivot stopper flange towards said free upper second safety hinge-joint member end and said second transverse pivot stopper flange having a leading second transverse pivot stopper flange end towards said free upper second safety hinge-joint member end, said leading first transverse pivot stopper flange end and said leading second transverse pivot stopper flange end being spaced apart in a folded standing ladder and abutting against each other in an open safety hinge-joint at said open safety hinge-joint limit.

2. The ladder according to claim 1 wherein said integral restrictor further includes a fixed length restrictor extending between said first safety hinge-joint member and said second safety hinge-joint member and spaced apart from said safety hinge-joint pivot, said fixed length restrictor hanging loose in a folded standing ladder and being taut in an open safety hinge-joint at said open safety hinge-joint limit.

3. The ladder according to claim 1 wherein said integral restrictor further includes a hinge restrictor including a first restrictor member having a free upper first restrictor member end and a free lower first restrictor member end and a second restrictor member having a free upper second restrictor member end and a free lower second restrictor member end, said free upper first restrictor member end being pivoted with said free upper second restrictor member end, said free lower first safety hinge-joint member end being pivoted with said free lower first restrictor member end, and said free lower second safety hinge-joint member end being pivoted with said free lower second restrictor member end, 267175/ said first restrictor member including a first transverse pivot stopper flange towards said free upper first restrictor member end, said first transverse pivot stopper flange having a leading transverse pivot stopper flange end towards said free upper first restrictor member end, said second restrictor member including a second transverse pivot stopper flange towards said free upper second restrictor member end, said second transverse pivot stopper flange having a leading second transverse pivot stopper flange end towards said free upper second restrictor member end, said hinge-joint restrictor being folded in a folded safety hinge-joint and substantially straight in an open safety hinge-joint, said leading first transverse pivot stopper flange end and said leading second transverse pivot stopper flange end being spaced apart in a folded standing ladder and abutting against each other in said open safety hinge-joint at said open safety hinge-joint limit.