Patent ID: 8550522

Claim:
A tool for raising and lowering a wind turbine blade, the tool comprising: a structure having an upper part and a lower part articulated to each other, wherein the upper and lower part of the structure define a closed contour; a hooking element configured so as to allow the tool to be suspended from a first crane; and a cradle-shaped support attached to the lower part of the structure for housing the blade, said cradle-shaped support comprising two portions, wherein the upper part and the lower part of the structure are articulated with respect to each other so as to move between an open position configured to receive the blade inserted in the closed contour defined by the upper and the lower part of the structure, and a closed position in which the two portions of the cradle-shaped support are in contact with the blade; the tool further comprising springs, fixed to the structure, and having a stiffness which is so high as to allow the springs to exert an opening force on the structure so as to maintain the structure in the open position in the absence of a blade within the structure, wherein the stiffness of the springs is so low as to allow the structure to reach the closed position by the combination of the effects of at least part of a weight of the blade and a vertical upward force applied to the hooking element.