Patent ID: 8381875

Claim:
A lambdoidal ladder comprising: a pair of front struts; a pair of back struts; a plurality of treads; a plurality of connection devices fastening the plurality of treads between the pair of front struts; a folding device having an H-shaped hinge, the folding device attached to a respective middle part of the pair of front struts and the pair of back struts; and a platform comprising a body and a transverse rod, the body having a bottom and an edge, the edge extending downwardly to form a periphery, the transverse rod passing through respective top ends of the pair of the front struts and joining the periphery, the bottom having a plurality of transverse reinforcement ribs, each of the transverse reinforcement ribs having an orientation slot, the plurality of the orientation slots forming an orientation groove having the transverse rod within the groove, the plurality of transverse reinforcement ribs joining the periphery, wherein the front struts are fixed to the bottom of the platform and the back struts are pivotally connected to the bottom of the platform resulting in a pivotal connection between the front struts and the back struts.