Balancing system for high capacity cranes

Claim 1

A high-capacity crane comprising a support structure, a chassis mounted on ground engaging drive means and mounting said support structure for rotation about a vertical axis relative to said chassis, a jib and a counter jib pivotally mounted on said support structure, a hoisting cable connected to said jib for hoisting a load, an I-beam in the form of an arc of a circle spaced from and centered on the axis of rotation of said rotatable structure and positioned to be on the opposite side of said axis from said jib, an upper surface for said I-beam, means for releasably anchoring said beam to the ground, an anchoring device mounted for movement along said beam, carriage means for preventing vertical upward movement of said anchoring device relative to said beam as said anchoring device moves along said beam, at least one arm pivotally connected between said chassis and said beam, an arm pivotally connected between said anchoring device and said support structure, a retaining cable connecting the upper end of said counter jib to said device, said device moving along said beam according to the angular orientation of said rotatable structure, a variable length pulley system connected between said jib and said counter jib to adjust the inclination of said jib, a pulley system to adjust said counter jib connected between the upper end of said counter jib and said support structure, said pulley systems and said cable positioning said jib whereby said device exerts pressure beneath said upper surface before loading said jib, whereby when said releasable anchoring means is released from the ground the jib, counter jib, retaining cable and hoisting cable cooperate to lift the beam from the ground for transfer to other locations.