The raw materials of ladders
In accordance with a first aspect of the present invention there is provided an Aluminum Rampcomprising two elongate ladder sections having feet at one end and an upper end, the upper end of each section being hinged to an upper rail, a platform pivotally secured to one ladder section below the upper end and adapted to interconnect with the other ladder section, and stays interconnecting each side of the ladder sections whereby when the ladder is in an operative position with the ladder sections assuming an erect A shaped profile with the platform extending between the ladder sections to define a standing platform, the ladder sections, upper rail and stays, define a four bar linkage.The ladder is preferably foldable for transportation whereby the frame sections rest one against the other. Preferably in the folded configuration the platform and upper safety rail folds within the plane defined by the ladder sections.
Preferably, the platform is coupled to the other ladder section by at least one platform stay whereby as the Aluminum step ladder sections are parted from the folded configuration the platform stay controls a lowering movement of the platform until it engages the other ladder section when the sections are fully parted to assume an operative position. The ladder of the subject application is preferably manufactured in composite materials of fiberglass and aluminium,The Products such asfiberglass ladders . The elongate components such as the stiles and feet are constructed of fiberglass whilst the rungs and platform of the ladder are constructed in aluminium. The method of construction of a ladder of composite material is described in U.S. Pat. No. 5,427,198 the disclosure of which is incorporated herein by reference. Fiberglass is a particularly useful material in ladder construction due to its lightness and strength and lack of electrical conductivity.
In the illustrated embodiment the elongate fiberglass styles use aluminium capping members at the end and pop rivets are used throughout the Aluminium ladder to join the various componentry. It is however understood that other fasteners can be used in the assembly of the ladder.It is understood that the invention is applicable to platform ladders of differing dimensions so that a variety of effective heights are envisaged, usually with the platform being between 600 mm and 3600 mm above the ground.