Bridge crane with articulated rotary boom

Bridge crane with articulated rotary boom, which includes a beam having a predetermined span that supports the boom, the boom being able to rotate in a substantially horizontal plane about a substantially vertical pivot, said substantially vertical pivot being located substantially at the centre of the span of the beam and being fixed below the beam, the boom consisting of at least two elements which can be positioned vertically in relation to each other, the boom being anchored by means of its first element to a rotary platform positioned below the beam, the bridge crane being characterized in that an operator's cage and a motor unit are provided on the rotary platform below the beam, the motor unit being offset laterally in contraposition to the boom as to act as a counterweight, the first element of the boom being able to move relative to said substantially horizontal plane and to be positioned vertically by means of a first cylinder/piston actuator, wherein the first element is conformed as an articulated quadrilateral and comprises a first bearing arm and a second arm supporting movement of said first arm, said second arm being shorter than said first arm, the first arm being anchored to said rotary platform at one end so as to be able to oscillate relative to the substantially horizontal plane and to a connecting bar at its other end, the connecting bar bearing a second element of said at least two elements of said boom on a pivot so that the second element can oscillate by means of a second cylinder/piston actuator.