Load weighing link member on a crane arm

A load weighing link member on a crane arm, comprising:

• a first eye furnished with a first bore on a first terminal end, the first eye extending in a first direction along a first substantially horizontal geometric axis (x);
• a second eye furnished with a second bore on a second terminal end, the second eye extending in a second direction along a second substantially horizontal geometric axis (y) which is perpendicular to said first substantially horizontal geometric axis (x), wherein said first and second eyes are firmly connected with each other via a central area which is mechanically rigid and elastically deformable;
• a link member is adapted to form a connection which is freely pivotable around each of said horizontal axles (x, y), wherein link member is freely pivotable around said first horizontal axis (x) via a first pivot joint of the link member connected to the arm of the crane, wherein the link member is freely pivotable around said second horizontal axis (y) via a second pivot joint, wherein a grabber or rotator, which is connected to the grabber and is adapted for enabling a controlled rotation of the grabber around the substantially vertical geometric axis (z);
• a plurality of sensors installed within an elastically deformable central area of the link member, wherein the plurality of sensors are suitable for detecting deformations of the link member which are generated due to the weight of a load held by the grabber hung on the arm of the crane, wherein said elastically deformable area together with said first and second eyes forms a rigidly interconnected stirrup, which is generally tubular and is weakened by an extensive internal passage which has either a circular or a polygonal cross-section, wherein the internal passage is symmetric with respect to said substantially vertical geometric axis (z), wherein said internal passage comprises two embedded elastically deformable lateral walls and extends along a substantially horizontal geometric axis (x′), which extends parallel to the geometric axis (x, y) of one of the first and second eyes;
• a measuring beam disposed within the interior of said internal passage approximately in the area of the longest distance between said lateral walls, wherein the measuring beam is rigidly connected to both lateral walls in a section that is elastically deformable and stable in view of buckling at least in a longitudinal direction (y′) extending perpendicularly to said longitudinal axis (x′) of the internal passage, wherein said measuring beam comprises at least one flat surface, which extends in a direction of said longitudinal axis (x′), and onto which the plurality of sensors are attached, wherein the plurality of sensors are electrically connected with each other and are suitable for measuring extensions or contractions of said measuring beam in the direction of its longitudinal axis (x′) resulting from elastic deformations of the central area due to varying distance between the lateral walls when the link member is exposed to stresses in a direction along said substantially vertical geometric axis (z).